Tracker vs. No Tracker for ASTROPHOTOGRAPHY (Shooting the Pleiades)

And if you’re still having trouble finding it look for Orion’s belt which is you know really evident and make an imaginary line between Orion’s belt and Aldebaran which is the brightest star in Taurus and then just keep following that imaginary line until you find the Pleiades. If you have exceptional eyesight and if you you’ve allowed your eyes to adapt under a very dark sky you may see seven or even more stars in the cluster. Here on the East Coast of the US typically i see at most six stars.

But tonight instead of just looking at it, which is fun, we’re gonna photograph it and we won’t just be photographing the stars themselves but the beautiful blue reflection nebula that is intertwined all around the star cluster. A reflection nebula is literally interstellar dust lit up by starlight and the pleiades are very hot B-type stars that shine blue which is why the Pleiades reflection nebula takes on its characteristic electric blue color seen here.

We will photograph the Pleiades with a stock 10 year old DSLR, the Canon 60d right here and a telephoto lens with 200 millimeter focal length. To make this even a bit more fun though i’m going to show photographing the Pleiades two ways: First just on a stationary tripod like this with no star tracking and Second with a popular star tracker called the Sky-watcher Star Adventurer. We will compare all aspects of the two ways of photographing the cluster, as well as the final results, in a showdown of: tracker versus no tracker.

Hello, my name is Nico Carver and i’m an astrophotographer astrophotography simply means photographing the night sky and there are many different ways to go about it tonight i’m going to go over the steps of photographing the pleiades in two common ways first with just my camera and lens on a fixed tripod and second i’m going to add a star tracker device in between the tripod and the tripod’s ball head and this device is going to slowly counteract the earth’s rotation just by slowly moving the camera like this and this will allow us to shoot longer exposures than we could on a fixed tripod we’re going to capture a total of 30 minutes with each setup process them the exact same way and then compare the results at the end which should be interesting before we get started i just want to very quickly say that this channel is supported by my patrons over on Patreon if you’d like to join it starts at just one dollar a month and i truly appreciate all the support that i get over there we’re going to start tonight with an overview by going through just quickly what’s the same and what’s different about shooting the pleiades with a star tracker versus without one just on a tripod if you don’t understand all this terminology now uh and you’re new to astrophotography don’t worry because after this overview i’m gonna explain everything in depth when we go through step by step okay so the first thing in the overview is we need a dark moonless sky this is really a necessity for a blue reflection nebula so yes right now we are shooting from a dark sky location on new moon with both setups number two camera settings we want raw file format no noise reductions no lens corrections no auto rotate all of that any camera settings other than exposure length we’re going to set the exact same number three polar alignment and balance this is something we only have to do with the star tracker setup and these techniques do require a bit of practice and time to get down i want to emphasize though that they are necessary with the tracker you can’t skip them but i will say the wider your lens the less accurate you can be with your polar alignment for instance if i was using a 24 millimeter lens rather than a 200 millimeter lens then a rough puller alignment even with a laser pointer would be fine but at 200 millimeters i really want to take my time at the polar scope and get this polar alignment step as precise as i can to get good results with a tracker number four focus i’m not going to sugarcoat it focusing on the stars is difficult it’s going to be more difficult than focusing during the day you can’t use autofocus one thing that makes it a little easier is an inexpensive Bahtinov mask and i’ll show that but focusing is going to be basically the same with both setups the only thing with the star tracker is you have to be careful when focusing not to bump your tripod and mess up your puller alignment number five exposure length this is a the biggest difference probably to calculate exposure length with no tracker but just on a tripod we’re going to use the NPF rule which i’ve talked about in other videos and that’s going to tell us at 200 millimeters we want to take one second exposures with a tracker instead i usually do tests and and i started around 30 seconds if 30 seconds looks good i look at the histogram i’ll just go with that if i if i push it to one minute and the stars aren’t just round then i’ll then i’ll back down to 30 seconds it’s it’s it’s more of a trial and error process okay and the number six is number of exposures or we also call these lights and here again it’s a big difference when you do deep sky to photography you typically take many exposures of this of the deep sky object and you stack all of these exposures or light frames same thing together to bring down the noise and to make this comparison fair we’re going to stack enough lights to get to 30 minutes total integration on each setup but to get there without a tracker at just one second each it’s going to take about 2 000 lights while to get there with a tracker at 30 seconds each let’s say it’ll only take 60 lights number seven calibration frames bias darks and flats if you haven’t heard these terms before don’t worry we’re going to go over exactly what they mean but we want at least 40 of each kind these are going to be take them the exact same way with both setups the only difference is with the tracker the darks will take a little longer to create because they have to match the length of the lights and finally processing we’re going to do the exact same so i’m only going to show it once and then we can compare the results at the end and see if we can see any difference between the tracked results versus the untracked results given 30 minutes total integration on both so that was just a quick overview of what this video is now i’m gonna jump into each of these eight topics in order and show you how to do them in detail so you can follow along and do this yourself when they’re done the same way with each setup like calibration frames are gonna be done the same way then i’m only gonna show it once but whenever there are differences i’m going to show it first with the tracker setup and then with the no tracker setup and so we can compare and contrast any differences in using these two different systems the first step in our adventure of photographing the pleiades is for both setups we want a dark moonless clear sky and to find such a sky let’s look at some free websites i use to plan out my night the first one is light pollution map dot info and i’ve pulled it up right here it gives you a pretty good general idea of where dark skies may be located in your area so it has a full world map you can just drag it around you can zoom in and out and you can search for your area right up here under search places it uses satellite data so this is a particular survey called the world atlas 2015 that’s the default one on here i typically switch between that one and just whatever the latest survey is and they give you slightly different colors but the key thing is that cooler colors like blue and black um and green are your darker skies and warmer colors like yellow orange red and pink and white are your light polluted skies and so you can see here these are cities this is the city of boston this is the city of new york i live right here in Somerville Massachusetts so close to the worst location you can find for light pollution so what i typically do is i drive a couple hours away from here to a green zone or a blue zone if i can to do my astrophotography one thing i want to point out is just because a dark site exists near you so like we could go out here and and know that we’re under a dark sky doesn’t mean that that spot is going to be good for doing us astronomy because it might be like a forest where when you look up all you see is the tree branches and leaves so you need a you need to find like a big field or overlooking an ocean or something like that where you have a nice horizon and this can be sort of tough actually a lot of times though if you look for parks that have parking lots or fields like athletic fields those are good places to go if you do find a park so if you zoom in and you find a good park that to go to that’s in a nice dark spot make sure to call that park ahead and make sure they allow and can give you permission to be there overnight another strategy other than calling up park departments is ask around at a local astronomy club so most major metropolitan areas have astronomy clubs and then they may have a spot outside of the city that you could go to either just places where they’ve made arrangements with people or sometimes astronomy clubs will have land that they have for club members okay so that’s light pollution last thing i’d say about it is for instance here where i am in somerville if i have my camera pointed this way to the northwest that’s my best direction so any deep sky objects that are over in the northwest will be in a slightly darker sky or substantially darker sky than if i point my camera to the south east where i’m shooting right into the light dome of the city of boston so it’s another thing to just when you’re looking at this map think about the direction that your deep sky object is in the sky as well and then look and see if there’s going to be something interfering with that okay now once we found our dark site we actually have to think about the day that we’re going to or night that we’re gonna go shoot for a blue reflection nebula like i mentioned we want this to be during the new moon phase or when the moon has set behind the horizon so for both the new moon phase week and for finding out when it’s going to be clear i recommend clearoutside.

com i think this works worldwide at least it seems to when i type in different um places up here and i like it because it does a number of things pretty well it gives a forecast i’ll talk about the accuracy that forecast in a minute but it also just lists the moon phase right here it does a full week which i like and you can quickly scan it to see you know green is good green is when it’s supposed to be clear red is bad orange is bad so i can see tonight if i open this up tonight it seems that for my location it’s supposed to be clear for the next you know or clear-ish for the next four hours then three hours of clouds and then another four hours of clear so we’ll see if that actually happens i just looked outside a moment ago and i did not think that uh only 14 of the sky was obscured by clouds i think it was more like 80 so you have to take these forecasts these cloud forecasts with a grain of salt even the day of they’re often wrong which is why i usually check multiple different sites in addition to clearoutside.

com i’m usually checking meteoblue that has this under outdoor sports it has a special astronomical seeing forecast which also gives you a cloud forecast broken up into low mid and high clouds so according to meteoblue right now about 76 percent of the sky is obscured by clouds which actually is much more accurate to what i just observed and my only hour of somewhat clear skies is going to be the 10 o’clock hour according to this one so um typically yeah i check multiple forecasts they’re never always correct there’s not one that’s definitely more correct than the others i’ll just mention one more i think it’s north america only but it has a really nice interface astrospheric.

com yes this is for north american astronomers one thing i like about this one is it has a cloud map so i can sort of see when the clouds are coming and where they’re predicted to go and that’s just sort of nice because i can maybe sort of get an idea for multiple locations i might go to just in one quick glance with this one if i did want to change the location on this one you just can either search or you can click on the map and change it okay so three things to look for again are a dark sky a moonless sky and a clear sky and so to find that we need to look at light pollution maps we need to look at the moon phase and we need to look at cloud forecasting okay moving on to camera settings we’re going to start with the camera’s quick menu and i’m using a canon 60d but hopefully you’ll be able to follow along with whatever kind of camera you’re using and the quick menu is basically just your commonly used settings so we have shutter speed aperture and iso up here at the top and i’m going to talk about how to set the iso and shutter speed in a little bit later in the video but in terms of aperture we just want to set this to the lowest number possible the aperture is a fraction so this means 1 over 2.

8 which means a wider aperture meaning more light coming into the sensor and so whenever you have a choice just make it as low as possible and generally for this technique we want f4 or lower so if you have a choice of different lenses and one of them the minimum is f 6. 3 but then on another lens you can go down to f4 or f 2. 8 choose that at one that has the wider aperture okay other thing i’m going to turn on before we leave is i’m going to turn on the two second timer this is really useful when you’re taking test shots so that you can press the shutter button and then it waits two seconds before actually taking the picture so your test shots aren’t ruined by vibration now once we actually are going to start our sequence of exposures we would want to turn this back to just single shooting so that it doesn’t add two seconds every time we take a picture i’m going to go into the big menu now and the most important setting camera setting that if you if you forget about anything else you want to make sure this one is set correctly is you want it set to raw you don’t want to have your so if it was set to jpeg only it would look like that right that would just be a jpeg and so if we just shoot jpeg our calibration isn’t going to work and so we don’t get the benefit of calibration frames and we don’t get the benefit of the raw file space which gives us more information to work with so because it’s not pre-stretched by a curve within the camera’s computer so i’m going to go ahead and fix this here and just have it set to raw basically every other camera setting is really just about disabling stuff so i disable the beep i disable the image review now when you’re doing some tests you may want to keep this on but i i prefer just to go to playback mode rather than just see the image for a couple seconds you really want to be able to go to playback mode and zoom in and all that so i don’t find the image review helpful and it just drains the battery so i just leave that off any kind of other you know reduction red eye reduction disable that picture style white balance don’t actually matter for shooting raw but i usually just set the white balance to daylight because it’s a question i get often again a color space doesn’t really matter for shooting raw but i just have mine set to adobe rgb exposure simulation i think you want to enable that because that makes the screen um brighter okay here’s an important one auto rotate make sure to turn that off that has screwed some people up because when you’re when the camera is changing position all the times if it has that auto rotate setting sometimes it can that can really screw up because your calibration frames and your lights uh your actual pictures the night sky don’t match uh geometry anymore and and i’ve seen people have issues with that so i would definitely turn that one off format i’ll just mention quickly here i’m starting with a fresh 64 gigabyte card um but if you’re not go you would want to make sure to back up the card to your computer or hard drives and then format it so you have a nice fresh slate to go with you could do a sensor cleaning before you start but i would recommend disabling the auto cleaning while you’re doing astrophotography so then if for some reason you know you have to change the battery or something it doesn’t change the position of the dust for between your lights and your flats so i would maybe just uh clean at the beginning of your session and then just make sure that that is that the auto cleaning is disabled and my camera is so old that it doesn’t have different noise reduction options but if your camera does have any kind of noise reduction options go ahead and turn those off as well okay and that’s really it for camera settings just disabling most things but making sure that the image quality is set to raw and then again in the quick menu i like to turn on the timer and just familiarize myself with where the shutter speed the aperture and the iso are make sure the aperture is set as wide as it will go for your lens one last thing i’ll just mention about the quick menu is sometimes when i’m doing my test exposures i’ll turn this iso up to as high as it will go because you’ll get a brighter image that way one more thing actually about bright images is if your camera does support changing the brightness of the screen itself make sure you can turn that screen brightness all the way up which is going to help you focus and see stars and things like that when you’re doing your test shots then when you actually start your sequence of exposures to save battery life you can turn the brightness of the screen back down i don’t think my camera has that setting so i’m just going to mention it here in case your camera does okay next camera setting uh we have to calculate or find out for our camera is the camera’s iso and uh this is something that causes a bit of confusion when you get into deep sky astrophotography the reason is is because with daytime photography iso is something that’s often misunderstood and people uh basically say falsehoods about it because to simplify or because they don’t know any better people often say well higher isos add noise and the truth is the higher isos aren’t adding any noise but when you go to a higher so you are typically reducing the exposure time and so you’re capturing less light um and so you’re good when you’re capturing less light you’re going to see more noise you’re going to see more of the camera’s uh noise patterns and uh so anyways i don’t want to get too much of an aside here but uh basically just what you’ve learned about iso is probably wrong if you think that high isos create noise and um i’m going to give you my two cents using a source that i trust which is bill class photons to photos you go here you go to the fourth link down which is the input referred read noise chart and this plots read noise versus iso you click on your camera over here so i’m going to pick the canon 60d and you just find an iso where this read noise starts to level off so for me that would be iso 1600 i could go up to 3200 which is sort of what i recommend if you’re doing uh astrophotography without a tracker so basically where it starts leveling off you can sort of see is around iso 1600 we don’t we definitely wouldn’t want to pick one of these isos because the read noise is substantially higher so for tracked astrophotography i usually pick the lowest iso where it really starts leveling off and for untracked astrophotography or photography just on a fixed tripod i pick the next one up so um in our case uh for this test for the tracked astrophotography the one that we’re doing on the skywatchers star adventure i’m going to use iso 1600 and for the untracked astrophotography the one just on the tripod i’m going to use iso 3200 we we could even go up to 6400 but we wouldn’t want to go up to this 12 800 you can see that all of these have these little circles these filled in circles but this one has a triangle and that means that it’s a scaled setting um just if you see the triangle avoid that iso setting um you want a natural one where it’s it’s just using the camera’s uh natural amplifier and isn’t doing any kind of data scaling which this triangle represents okay um let me just mention quickly here that one reason to get a newer camera which you’ve probably heard is that they have lower noise and this is true like if i plot the canon 6 the canon 90d a much newer camera you can see it has substantially lower read noise across the whole iso range and nikon and sony’s often have very low noise as well and one other thing that’s sort of interesting here is you can see with canon cameras they have this sort of stair step uh down until the until the read noise sort of levels out well with a nikon camera with a sony sensor it’s pretty even all the way across so with something like that it’s harder i think to pick the right iso value it’s not as clear you know where you would where you would pick on this one but generally for something like a reflection nebula and stars if i had a nikon crop sensor camera that had much more flat chart like this i would pick a quite low iso setting maybe like 400 if i was doing tracked and i would still probably go with 1600 or 3200 for untracked for just on a tripod but with this particular camera the highest i would go is maybe 1600 or two thousand because after that you can see the the little symbol changes to triangles which means they’re doing some raw data scaling which is what we want to avoid so stick with the range where it’s in the little circles and with just on a tripod you’re running good wanting to go to a higher iso and if you have a tracker with this camera i would probably go lower like iso 400 to recover more dynamic range okay this has just been a brief primer on how to use this site i’m not going into a lot of depth with this and explaining what read noises and everything else but if you have questions you can always ask them in the comments this is this site’s also cool and that you can compare you know different cameras and see how they compare in terms of read noise which is an important noise term in terms of deep sky astrophotography and cameras the next thing we’re talking about is polar alignment and balance which only applies to the sky watcher star adventure or whatever star tracker you’re using i like to balance first and at least get the the approximate balance then polar line and then very carefully put my whole payload back onto the mount because i find that if in balancing it’s very likely that you’re going to throw off the polar alignment if you’re trying to do too much after you’ve fully aligned if this makes sense hopefully it will once once we go through it here so to balance this mount we’re going to release the ra clutch here and you can see immediately it starts turning when i release our the right ascension clutch and i can tell right away that it’s camera heavy because the the camera side up here is falling see and then the counterweight side is going up like that so all i’m going to do is i’m going to take the counterweight right here i’m going to gradually lower it until i find balance so it seems to be right there and i’m just going to make sure that that holds in any direction that i put the camera and it does so you can see i can now put the camera on lens anywhere and it’s still balanced and basically the point of of balancing like this is so that the the gears can work a lot smoother as it’s just turning this more effortlessly if everything is balanced if there’s a lot of unbalance then you’ll have more slippage and problems so this is a really important step with star trackers especially the heavier that your payload up here gets the closer you get to the payload limit the more important this is and also the longer the focal length if you’re working with a wide angle lens then this balance step wouldn’t be quite as important okay now that we have that balance we want to mark or just remember exactly where this declination bracket is clamped in here so that after we pull it aligned we can very carefully put it back in not disturb the polar alignment and don’t have to rebalance which might throw off the polar alignment let’s go ahead and move on to polar alignment so to do this i’m going to go ahead and take out this whole piece here so i’m going to take out the declination bracket with the counterweight shaft the counterweight the camera the ball had everything that’s on top there and i’ve just covered the polar scope with a little piece of tape because i lost the cap that comes with it basically we we uncover the polar scope here we take this cap off here so that we can look through the polar scope which goes right through the axis of the mount and the first step is we want to find polaris and i can see it right there and i’m going to line up just by actually lifting up my tripod and moving the whole thing okay so now i have the this mount roughly lined up with polaris right there if you’re not sure where polaris is in the night sky um you can just use a compass like on your smartphone or if you have a magnetic compass and just point find north and then you should see polaris it should be a bright star that’s you know it’s the end star in the little dipper not too hard to find uh once you get a little bit used to looking at the constellations so this is the first step we’re gonna visually line it up okay the next step i’m going to go ahead and set my latitude on the the base here so i’m just going to go ahead and loosen this up and then i can go up and down right here and so i can set this to our latitude right now which should be around 43 degrees and then i can tighten it back up and so now this is nice and tight and we’re not having any movement uh that way now we might and so you know see if i do this it doesn’t actually go up and down you have to loosen this one and then you can use this one to do the adjustment now we’re probably gonna have to return to this adjustment when we actually do the polar alignment the other adjustment i’ll just point out right now since we’re right here when we actually do the polar alignment is this knob right here so this is the azimuth and this is the altitude and so we’re going to basically you can think of the altitude as up down and the azimuth is left right and so to use these later you always have to loosen one and then tighten the other and that can move it left and right so if you need to move it you know left in the view you loosen one you tighten the other and so forth it’s just a push-pull system against a pin in there same thing with this you you loosen one and then you can tighten the other it’s a push-pull that way okay so now i’m finally ready to actually look through the scope and when i’m looking through the scope i also have open an app that i’m going to look at and this app tells me given my location which it finds using the phone’s gps and the time of day it tells me where polaris should sit in this circle that we see this is the reticule so we’re going to see the same kind of reticule in the polar scope and we can see that polaris we should position right at around 5 30 if you think of this as a clock and so that’s where i’m going to aim for when i’m actually adjusting it if you don’t see polaris in the view you can just pick up the whole tripod and just and just readjust until you see it in there the one other thing i’ll say is for me personally i like to start with the tracker off because as soon as you turn it on it will put on a red light in the polar scope and to me i find that red light distracting at first i might turn it on at the very end but for the most part i like to do this just in the dark my eyesight is good enough that i can sort of make out the reticule just from the starlight but if you might be different your iso might be different so you might want to turn on the mount and then it will illuminate the the polar scope with a red light on most trackers and mounts so i just showed you polar alignment and balance with the tracker setup and i just want to reiterate here that with the no tracker setup polar alignment and balance is not applicable or is not a necessary step because with a fixed tripod there’s no need to do it so that’s the end of step three moving right on to step four i’m just centering up the pleiades in my live view screen here and once i have it centered i’m just moving the ball head to do this on either setup we can start focusing and let’s start by just trying focusing without any kind of aid so all i do all i’ve done is turn the manual focus switch to manual focus on the lens and i’ve racked the focus all the way to infinity and then we’re going to zoom in on live view on the pleiades and here’s what the stars look like and i can tell these are out of focus uh if you are new to this you might not know that these are out of focus the the dead giveaway for me here is that they look sort of like donuts with a brighter ring around the edge and then they’re more dim in the center and so let me rack focus and you see how it can change change when i’m doing that and one thing i want you to notice is that when i get into focus here a lot more stars pop into view also so these dimmer stars are coming into view as well as the brighter stars are getting a lot more concentrated and have a bright core and so this is what you’re looking for when you’re manually focusing with a 10 times zoom in on live view here now i just also want to show you if you do have a Bahtinov mask what to look for so let me put the Bahtinov mask on the front of the lens and we’re going to do the same thing here and basically it’s going to be hard for me to show in video but i can see that there is a little x pattern there let me go ahead and take a test picture though and then go into playback mode and then you can really see the x pattern quite clearly so here it is you can see on all the stars there’s an x pattern but it’s really evident on the bright stars and then we just have to remember when if we do use a Bahtinov mass to take it back off from the front of the lens before continuing it’s really just an aid for focusing you don’t want to leave it on to figure out the best exposure time for uh tracked astrophotography you have to sort of know the limits of your particular gear and so if you have a really excellent equatorial mount that’s nice and heavy and you know that you can do five minute long exposures without any star trailing then you might be able to go with five minute exposures and that would work really well for a star tracker like this i generally am pretty conservative and at 200 millimeters i would start at somewhere around 30 seconds and 30 seconds though is plenty to give you nice exposures you can see that we can see nice reflection nebula showing up even in a single 30 second exposure this is what dark skies gets us and so i can tell there’s going to be lots of nice detail from this even in a 30 second exposure but i can also see that these stars are right on the edge of starting to trail even at 30 seconds i did go up to 60 seconds and they were starting to trail more so i know this is the limit of my mount right now i know that you know some people may not want to hear this some people probably get better results than i do on a star tracker but it’s really just about figuring out for yourself where your limits are with your equipment okay the other rule though that i want to mention for judging exposure on a tracking system is the histogram rule and so it’s not it’s not so much a rule is just a useful tip here figure out on your camera how to bring up the histogram and playback mode on my canon camera i can press info twice and bring up the histogram like that and this uh gives me um all of the information that’s in the picture all the pixel values and it charts it on this little uh graph here and i can see that that histogram peak is almost at one quarter of the way over and it has plenty of separation from the left hand side that’s the most important thing is we don’t want it squashed up right on the left hand side we want a little bit of separation from the left hand side so we’re getting away from the noise floor of the camera the other thing to look at if we hit the info button again is the different color channels and you can see that all three color channels look pretty healthy there they’re all moved over from the left now typically a advice you’ll often hear is get this histogram peak one quarter over from the left or one third over or even one half over and so those are all good too you’ll get plenty of data that way i’m not convinced that we actually need to get it much further over than what i’m showing right now but one quarter over is is a good rule of thumb um and so uh the histogram is really helpful to look at for judging exposure if you if i could get longer exposures and still have nice round stars i would probably push them a little bit further to get this histogram peak about one quarter of the way over from the left now when we stack many exposures together we’re going to recover a lot of dynamic range and and so you don’t have to think that this single exposure is what your final picture is going to look like because when we bring the noise floor down we can stretch the image quite a bit more okay enough said let’s look at the npf rule for untracked exposures okay next we’re going to look at how to calculate the shutter speed or exposure time for each light when we are doing untracked astrophotography just with a tripod and for this i recommend the npf rule it’s available on this free website which from this french astronomy society and the website is in french but if you’re using something like google chrome you can just automatically translate it to english there’s a little thing up here in the address bar to do an auto translation or you could probably translate it to whatever language you speak this website has been updated recently it makes it a little bit simpler in some ways and harder in other ways but i’m going to show the new website just because i don’t know how long the old website is going to be available through the wayback machine so with this new website instead of giving us a full list of different camera models it only gives us four different choices so if you have a full frame camera choose full format if you have a canon crop sensor camera you choose canon aps-c if you have a crop sensor camera from another brand you choose that and if you have a micro four thirds camera you would choose that and this gives it a general idea of the size and pixel size of the camera so you could probably just go with that but if you want to be more exact you can enter in things over here so let’s find out exactly what the pixel size and resolution of the canon 60d that we’re going to be using is so i’m just going to google canon 60d pixel size and one of the first results here is digicam database and it tells me right here pixel pitch same thing as pixel size is 4.

29 um or round up to 4. 3 and this sensor resolution i’m going to use this max image resolution right here so the width is 5184 pixels because it always goes with by height okay so 4. 3 and 5184 so we’re going to enter those in perfect and so now it knows the actual camera data for our camera so you would just do the same thing just google your camera plus pixel size figure those out from a website like digicam database the opening would be the same thing as the aperture ours is going to be 2.

8 but you can change this right here the focal length we’re going to be using is 200 millimeters because that’s the focal length of our lens where it says precision of formula you want to change it to point stars okay and then we have declination this is something you’d want to look up in like a stellarium or a planetarium app for whatever you’re shooting i’m shooting the pleiades and i just looked it up in my app on my phone and it says the declination is 24 degrees okay so we have everything entered now and this results part automatically updates and um usually what i go for is the full mfn or npf that for some reason it translates it to mfn but we want the full npf rule uh the calculation for was right below right here and it gives us 0.

7 seconds and i always just round up to the full second so 0. 7 i’m going to round up to 1. um if it said 1. 5 i would round that up to 2. so i just round up and that works well enough for me i’ll just mention briefly here this calculator is also built into the photopills app and that app does have a camera database so you can just quickly find your camera and don’t have to find out this information on your own um so that might be an option too if you want to check out that app photo pills next the number of exposures so for this constrained test we’re going to try to keep these two systems equal in terms of total integration which just means the total time when you add up all of the different exposures that you take and so we’re going to do about 30 minutes total integration for each system for the just the tripod and for the tracker but 30 minutes is actually a fairly scant integration in terms of deep skies to photography really uh you want to go if you have a tracker i’d recommend you know as many hours as you can um you know the best astrophotographers will typically you know not even show you an image of theirs unless they’ve gotten something like 20 hours over multiple nights i know we’re talking about sort of advanced things now but the point i’m trying to make is the more the better always because you can always keep bringing that noise down which is going to reveal fainter and fainter detail as you bring the noise in the picture down by taking more and more pictures of the same thing so for this test we’re doing 2000 around 2000 on the tripod and around 60 on the tracker it’s just so that we can compare you know apples to apples to 30 minutes here 30 minutes here we now want to take calibration frames so in addition to the light frames we also want these calibration frames and we’re going to start with dark frames for dark frames we want to leave all the settings alone same iso same shutter speed all we have to do is cover the lens with the lens cap so that no light is hitting the sensor now i’m sure many of you are wondering can’t we just take these later on after we go home the answer is no these need to be taken at the same temperature as the lights so you really do need to take them here on the field but with such short exposures these are really quick to take we’ll just we just want 50 so we’ll just leave the same setting on the intervalometer and we’re going to do one second each so we’re going to cover the lens hit start on the intervalometer and that’s it next up is bias frames you can technically take these anytime but we might as well take them now all we want to do is change the shutter speed i’m going to change it from one second down to as fast as the shutter can go on your camera for my camera here that’s 1 8 000 of a second and let’s take 75 bias frames okay and last up is flat frames and it’s important to take these very soon before or after you take your light frames because we want everything to be the same in terms of focus and any dust particles on the lens or the sensor so i wouldn’t even recommend turning your camera off if you can help it we just want to take these as soon as possible to take these we take the lens cap back off and we point the lens straight up and i’m going to rubber band a clean white t-shirt to the lens hood you want it to be taut with no wrinkles then we place a white screen on top and this can be any pure white screen if you have an ipad you can set to white or a laptop you can set to white that will work if you want to buy something just for this purpose what i’d recommend is an led tracing panel these go for about 30 bucks and they’re powered with a usb cable so whatever you have that produces a white light just put that on top and now we’re going to move the shutter speed up and down with the dial here until this exposure meter at the bottom of the screen is telling us we’re properly exposed to check that we just push the shutter down halfway and i’ll tell you right here so for my particular setup here it’s showing proper middle exposure at 1 40 of a second so i’m just going to set my intervalometer to take 50 and hit start okay i’m now on my computer this is a windows laptop that i’m using um so that i can use deep sky stacker and i’ve moved my files both my 60 lights and my calibration files to the computer so i can uh stack them using deep sky stacker and i’m just going to show this once with the tracked results but the only difference with the untracked results is you would need a lot more space on some hard drives to do this process because if you’re doing 2000 lights and a few hundred calibration frames that’s going to take up many many gigabytes of space and then it’s going to take up even more for the process because deep sky stacker does use a lot of hard drive space while it’s working and puts that all into a temp folder and so what i do is i use external hard drives to manage all of this because a lot of times like on my laptop here it it has a ssd that’s not very big so i need to use external hard drives to make this process work especially with the untracked results where i have so many files but anyways i’ve just organized my files copied them off the camera’s sd card into these folders lights which are again the um actual pictures of the night sky flats which are the flat frames which correct dust bunnies and optical problems like vignetting darks which match the lights in length and temperature and bias which are very very short dark exposures and i’m going to be using a free program you can download online called deep sky stacker it is windows only but if you are a mac or linux user i’ll have future videos in this series which show programs for those systems let me find it here there we go okay and i guess i’m not on the latest version but i doubt much has changed this is what the interface should look like if it doesn’t look like this if you’re seeing something radically different be aware that deep sky stacker is packaged with another program called deep sky stacker live for live stacking so make sure that you’re clicked into the regular deep sky stacker it should say up here deep sky stacker four point something and it should look just like this okay anyways let’s go ahead and start and you basically just go down this left-hand side um going through these different commands the one thing that i like to do um first before i do any of that is just set up my temporary folder um and i think this is under settings stacking settings yes here we go so um i’ve actually i think i’ve already actually set it up but uh what you would want to do and it will remember this setting if you’ve said it before is click into settings and then it’ll say temporary files folder and you just want to click on these three little dots and tell it where to put the temporary folder so like i mentioned before i don’t have much space on the computer here i only have six gigabytes so the process of stacking would definitely fail while on my external hard drive i have 164 gigabytes free and so i use that as my temporary folder okay with that done we can now load up our pictures so we’re just going to go up here into the upper left and click on open picture files and my folder is on the desktop and i’m going to start by bringing in all my lights so i’m just going to click on one press control a to select all and then click open okay and it brings in all of our light frames here but if we look right up here in this blue bar it says light frames zero and the reason for that is it only registers pictures that are checked and for some reason the first time you bring in some picture files it doesn’t check them so i’m just going to click check all over here on the left and somehow i thought i took 60 but it only took in 59 that’s okay close enough i might have deleted one that was bad or something um so we have 59 light frames and then we’re going to add our dark file so we just go down the list here and go into the darks folder and again select all open and now it starts checking them so i have 49 dark frames and then we’ll bring in our flats we’re going to skip over dark flat files so called these are files that would be darks that match your flat frames but since our flat frames are very short and we are using bias frames we don’t we don’t need dark flats uh they would be to correct uh thermal noise in your flat frames if you were using very long darks like with narrow band filters or something like that so i’m going to skip over those i am going to add bias files though ctrl a click open okay so we have everything loaded up here about 40 flats 50 dark 60 bias 60 lights okay and you know these numbers don’t have to be exactly your numbers you know yours may be different i would just always recommend at least 30 of each calibration file and as many light frames as possible the other thing we can do is we can just quickly scroll through here and looking over in this far right hand column i can see that these all are registering as the same size which is good if you have any with incorrect geometry you know mean a different size that might stop the process okay this is all looking good and i can also see that they’re all cr2s which is the canon raw file which is what we want okay that looks good so now we just have to check a few settings and then we can start the process and it just does its thing and then we have a picture at the end um one thing i will point out here is you can look through your files right here and so if you haven’t already looked through your light frames i would recommend looking through them and just making sure that they all have fairly round stars um and that you know there aren’t that have have any like huge streaks or you know stars that look really bad um or clouds or things like that if you do find any with clouds or anything you can just uncheck them and then it wouldn’t include them in the stacked result okay let’s go ahead and click on register checked pictures over here on the left you can see there’s a link right there and i’m going to click into advanced and click compute the number of detected stars okay and it found 2088 stars that’s perfectly fine i just want to show you if we take down the star detection threshold then it will find more stars and if we take up the star detection threshold it will find fewer stars because it will treat a smaller little things as noise um and so really it it anywhere from you know a few percent to 20 percent it really doesn’t i can’t tell you exactly where to set this but the point is you want it to be confident that it’s finding enough stars and i i often get the question well even when i set my you know threshold to one percent it says it’s only finding three stars if that’s the case then something went wrong with your capture because it should never have that much trouble finding stars and it’s the usual problems are that you weren’t tracking or using the npf rule correctly so you have stars that aren’t round or you are out of focus and then it can’t find the stars because it finds the stars based on their star cores and if it can’t if they’re really out of focus and it can’t find those star cores i’m going to select the best 100 of pictures and stack them because i’ve already looked through these pictures and i also want to get as close to a half an hour of data for each uh setup so we can make this a fair test i am going to click stack after registering and let’s go into the recommended settings and look through these these all look good if it was if it was finding anything weird and then i’m going to click on stacking parameters and just check this oh this is another thing i hear people talk about well why not enable one of these drizzles it’s going to make the picture bigger i’m not going to get into what drizzling is but i’m going to say if you if you don’t know about drizzle if you haven’t read about it don’t check these because drizzle is a specific algorithm that you really need well dithered data for it to work correctly and so i would not check one of those unless you know what you’re doing okay and then i just use sort of the recommended different stacking parameters through all of these and one thing i’ll note here is it will create an output file in the lights folder called autosave.

tiff you can certainly use that it’s a 32-bit tiff file or when you’re all done you can just click save picture to file and save it as a 16-bit tiff file which will work with basically any processing software we use after this like [ __ ] or photoshop okay this is all good i’m going to go ahead and click ok and click ok again it will give me a summary of everything and this all looks good and it tells me right down here how much space this process will temporarily use 6.

5 gigabytes now keep in mind that is going to be much much higher with the unstacked process where we’re stacking like like 1800 lights so just keep that in mind that this is one advantage of using a tracker is your file sizes will be a lot more reasonable okay i’m going to click ok and let it start doing its thing and so now it’s very automated it goes through all these different steps like creating calibration masters calibrating your light frames registering your light frames stacking them in in the end what you have is one calibrated registered stacked um light uh so basically it’s it’s all of this stuff all of these hundreds of uh pictures are used to make one final picture and then we take that and bring it into the next program okay so we’ll let it do its thing and then move on when it’s done with that final autosave.

tiff or like i said you can also save the tiff off as a 16 bit file with this save picture to file command over here and then we’ll bring it into the next program i’ve taken our output from deep sky stacker the 16-bit tiff file dss. tiff and i’ve brought it here into adobe photoshop if i go into image mode i can see that it’s rgb color and 16 bits per channel if you are just using the autosave. tiff you may consider changing it from 32 bits to 16 bits there’s you know some discussion about whether it’s better to do this before or after the stretch in my experience it doesn’t matter too much but if you are trying to get the very most out of your image you might want to leave it in 32 bits per channel do a stretch and then switch it over to 16 bits but a lot of things don’t work if it’s in 32-bit mode so that’s why i recommend for photoshop at least the 16-bit mode so we can actually see our histograms and things like that okay first thing i want you to do is go ahead and duplicate the layer so you can see that right now it just says background over here in the layers panel go ahead and right click on that and choose duplicate layer i’m going to call this new layer first stretch and then i want you to open up the histograms panel if you don’t see a little histogram panel over here on the right side go ahead and go to window and find histogram to open it up and then yours will probably look something like this and i want you to change it to all channels view so you can see red green and blue just like mine okay next we’re going to start stretching the image so we’re going to go to image adjustments levels and i’ll note here that when you access something from one of photoshop’s menus like we just did image adjustments levels it will give you the keyboard shortcut right over here since i’m on a mac the keyboard shortcut for levels is command l if you’re on a windows computer it would be control l and so l is for levels and this is just handy so instead of having to go to the menu each time and finding this we can just hit command l or control l on windows to bring up the levels because we’re going to be opening up this adjustment window a number of times okay here it is and the first thing that i want to do is i just want to move the values here off the left hand side so i’m going to do that by taking this middle slider the midtone slider and dragging it well over here over to the left and saying okay okay and now you can see that we have some separation some of the stars are coming out in the image and we’re just going to do that same thing one more time so we’re going to take this and we’re going to move it even further over we’re going to move that mid tone slider to the left again and all three channels will get moved out like this okay and i can see that we actually have really nice color balance because the left edge of these three channels is lining up quite nicely now you might see up here that there is a bit more blue in the highlights but that is completely natural because we are dealing with a blue reflection nebula so you don’t you wouldn’t want to correct this because this is is already correct because there’s going to be more blue highlights when you’re dealing with a blue nebula so this is quite good we don’t have to do any color balancing if these were more out of whack though because you’re maybe dealing with more light pollution than me what you would do is when you bring up that levels command you would just want to line up the left edge of these three by changing the channel from rgb to any individual channel and then you can see that you can move the channels around to line them up better just by grabbing one channel and moving it relative to the other ones so we can do some color balancing while stretching and if you are new to this i’d recommend watching some of my other tutorials where i do a bit more with color balancing for this data we don’t really need it because like i said it already is well balanced okay i’m going to continue stretching here and basically what i’m trying to do is in addition to bringing this this curve over i’m not really trying to bring it too much further over now but just widening it and the way we widen it is by taking the shadow slider and moving it to the right and taking the mid-tone slider and moving that to the left and every time we do that we’re going to widen out the curve and stretch the data more okay until we have something like this and you can see there is lots of really cool dust in this now uh in this tracked shot we’ll have to see well to compare this at the end to the untracked shot but i’m not so sure if we’re going to get this much dust away from the central region here this also looks quite clean even just for a half an hour of data and what i mean by clean is there’s not a lot of noise even when we zoom way in like this you can see there’s not much noise here it looks really smooth okay so all we’ve done so far is a stretch and it already looks really nice but from here we may want to do some saturation boosts so we could click on this hue saturation adjustment layer and one thing about just boosting the saturation globally like this is you can see it also is boosting the saturation of the sky background and so it’s making the sky background very sort of bluish i guess and so we could correct that by just bringing up curves and you know resetting the blue point the blue’s black point actually that worked really well i didn’t expect it to work that well so this is actually an excellent point when you’re really when you’re working with uh nice data with data that is really well captured and done on a tracker uh even simple adjustments like that just work incredibly well i guess i’ve gotten used to working with uh with astrophotography untracked which is always more difficult in the processing i might actually just stop right there that looks really nice what else could we do here with it well there seems to be maybe a little bit of a green to magenta shift i’ve noticed this dust over here looks a little greenish and over here the sky looks a little bit too magenta so let’s see if we can do some color correction on that what i’m going to do is i’m going to bring up a selective color adjustment layer i’m going to start with my blacks and i’m just going to take a little bit of magenta out of the blacks which i think let’s turn this off and on yeah i think that correct i’m looking mostly looking over here i know that the dust got really green by doing that but we’re going to correct that second so looking over here i think that did help correct that magenta tone and now i’m going to go back into that adjustment and i’m going to go into my neutrals and i’m going to add a little bit of magenta back and just take out a tiny bit of yellow okay i do like that so uh here’s sort of where i ended up with the neutrals color balancing you know it might not need so much a lot of times i’ll back off of these a little bit after it just needs to be a little brighter now sorry i’m sort of mumbling to myself let’s see okay so i’m going to go back here into my curves and i’m just going to add a couple points on this curve to brighten that up and then i’ll go into my blue curve okay do i like what i just did as a whole i’m going to go into my history panel and see here yes i do like that okay so i’m actually happy with this image as it looks right now i might crop it down a little bit but um just to make this a fair comparison and because i want to do the processing the same with both images and i feel that the the one that i just do on the tripod is going to need it i’m going to make a starless version of this with star net plus plus and then recombine it with this version the stars version so let’s do that so i’m going to make a new layer from visible so i’m going to do command option shift e or that would be control alt shift e on windows it just pastes a new layer from exactly what we have here and i’m just going to call this stars and then i’m going to save that i’m going to go to file save as we want the srgb color profile we want to turn off layers so it saves as a copy and i’m going to call it stars.

tiff and save it to the desktop then what i’m going to do is i’m going to google star net plus plus this is a standalone program that’s useful for removing stars from astrophotography and i’m going to download it from this sourceforge page and if you go to files up here at the top and then go into version 1. 1 they have a nice zip file for each main type of operating system so since i’m on a mac i’m going to download the mac version okay once that’s downloaded i’m just going to move the entire starnet macos folder onto my desktop here and open it up and then i’m just going to open up this run rgb starnet dot sh file with a text editor i’m just going to change these two file names be the first one being the input file so we called that stars.

tiff and then i’m going to change the output file to m31starlist. tiff this number is the stride and typically i use a lower stride when i’m at a lower focal length and a higher stride when i’m at a higher focal length um it starts at 128 but you can go down to 16. i’m going to change it to 64 for this image and typically the the lower the stride number the longer the process takes so if you wanted to see what will happen if you run it quicker you can leave it on the default 128.

okay then i just have to move this stars. tiff into the same directory okay with that shell file edited like this and the stars. tiff file in the same directory we now just have to run this file a terminal command so i’m just going to open up terminal and we have to get into this folder so the command for that is cd for change directory space and then i’m just going to drag this folder over and hit enter and then we just want to run this command or this sorry this shell script which calls on the actual program so to run it i’ll have to do is just drag it over and hit enter and it starts running it gives us a little information about the file it tells us how many different tiles it’s going to break it the image up into to analyze that’s what the stride number is so the slower the stride number the more tiles it will break the image up into and then the longer it’ll take and then it gives us a percentage finished so this will take some time probably 20-30 minutes on my laptop with an image this size star net plus plus is finished and i just brought in the starless result here back into photoshop so now we have two different files we have the stars file and the starless file right and so i’m going to go ahead and clean this up a little bit and what i mean by that is sometimes these dark spots where it removed the bigger stars can pose problems later on so what i usually do is i just grab my spot healing brush tool and make it about the same size as the the dark spot and this will just usually either get rid of them completely or just brighten them up a little bit so they won’t be as noticeable once we add back in the stars now you want to be careful when you’re doing this not to mess up the nebulosity too much so you wouldn’t want to do it right in here because there’s a lot of fine nebulosity in there that could get disturbed if you were to use this but there’s so much detail in here that i don’t think that we’re going to notice these artifacts so i’m just going to do them do this in areas where they’re away from the main action there’s different ways actually to clean these up you could also use the clone stamp which would be a little bit more sometimes work a little bit better because you have a little bit more control but i’m just sort of going for the the quick and dirty here okay and let’s do that one okay then i’m going to go ahead and just um do a curve here and just reset the black point on this and maybe just do a slight s curve like that okay i’m gonna get rid of these guys over here i’m probably gonna crop these away anyways but i’ll just grab them anyways okay and then uh this is looking pretty good the one thing i noticed is that we have a little bit of a gradient where uh even with the dust i think that it’s a little bit too bright over here so i’m just going to do another curves layer and just bring it down just a little bit and then that made this side way too dark we don’t want it to apply to this side so i’m just going to draw a gradient right on that curves mask and i want it to go from black to white from this side to this side because i want the curves adjustment to not apply to this side so this should be black and this should be white right and so that just evened it out a little bit you can see here’s before and there’s after okay good and now let’s go ahead and copy this i’m going to do command a command c or that would be control a control c on windows and command v or control v on windows to paste it in so we just took this entire thing the stars image selected it with command a copied it with command c and pasted it onto here with command v and then let’s go ahead and change the blend mode and we’re going to change it from normal to screen okay and then at this point i usually zoom in and i look at those bright stars where there were possible artifacts and i see if there’s anything left over that looks funky this looks pretty good one thing i will note about this tracked result is that it does really bring out the chromatic aberration on this lens especially probably because i shot wide open that’s all this sort of magenta pinkish halos on the stars so if you wanted to get rid of that there is a good way we could go into camera raw filter and under optics we can raise up this purple amount here and you can see if i turn this off and on that’s before see how it’s sort of pinkish and that’s after so that’s the easiest way to get rid of it is just go into camera raw filter optics defringe and take away purple and then click ok all right what else i think now the picture is too bright so let’s go ahead and reset the black point again just with another curves i’m just going to do something like that and it looks just a little bit too red in the background so let me open up that curve again and i’m just going to open up my red curve and just bring that over a little bit too do the same thing with green i like it right about there okay so i’m gonna call that done um there is one weird sort of black uh ridge down here and i don’t know if that is is right or if that’s something some artifact from the sensor or the lens or something but that looks a little weird to me other than that this looks really cool i like all of the extended dust and stars and the star color looks really nice especially after we got rid of that fringing i’m going to now try to process my untracked uh picture from deep sky stacker exactly the same way i did this one i may find that i have to do something with that picture that will adjust what i did in the processing here so the final result may not look exactly like this when we do the comparison don’t be alarmed if that’s the case um but i’m going to try to keep these processes as similar uh as i can and then we’ll jump into the final comparison and here we are the final result so uh we have the tracked result on the left and the untracked or fixed tripod result on the right and these again were both about a half an hour of data this one 1800 single exposures at one second each and this one 60 exposures at 30 seconds each and so i think this does show that in this at least in this extreme example having longer single exposures uh even if you get to the same total integration can be a huge help in resolving uh finer details and uh dimmer uh signals um so all this really faint nebula and stuff and all these beautiful star colors come through a lot better than they do over here even though these were shot under the same sky again 30 hour 30 minutes integration on each and i think the reason has to do with noise really because at one second long you’re just really not beating the the noise of the camera so you’re you’re stuck down in the noise of the camera and you the the signal really just never has a chance well at 30 seconds you like when we look to those histograms they were they were off the left-hand side so they weren’t down in the noise and uh that really just helps in the final result here now if you imagine this is just uh 30 minutes with the tracker if we went two hours or three hours or 10 hours you can just imagine how how good this would look because if we zoom in you can see there is still quite a bit of noise in both images you know they’re both pretty noisy but if we look at the fine details in the pleiades see how it comes out quite uh well over here this is you know the brightest part of the image looks really good even just with 30 minutes of data here well here you can still just see that a lot of that detail is getting lost in the noise from the camera now one interesting result that i didn’t expect is that with the longer uh sub-exposures chromatic aberration on the stars this sort of fringing around the all the stars uh was a lot worse in the uh version with the tracker over here uh we don’t have we don’t see that chromatic aberration but on the other hand the stars are not very colorful compared to this so i think i would rather have more uh colorful stars and have to deal with a little bit of that fringing rather than just have stars that are are a little bit subdued and mostly white oh one last thing that i want to mention is that i did this crop because this was as much usable frame as i could get out of the untracked result because i you know was reframing it pretty uh regularly about once a minute but even so a lot of the frame was not usable due to registration artifacts because when you’re reframing um you know the outside of the outer parts of the picture don’t get nearly as much data as the inner as the center and so but with the tracked result i could actually have done a much bigger crop than this and i probably would have i’ll show that now so i do like this close crop but i probably would go for a little bit bigger crop on this one okay this has been Nico Carver from nebulaphotos.

com i will just mention again that i do have a Patreon you can support me in a number of ways you can subscribe to the channel you know watch the videos like and comment but you can also if you want to support me financially i have some links down in the description including my Patreon link where you can set up a monthly or yearly donation and you’re about to see all of my patrons names over on Patreon they’re in the credits of any long video and i really do appreciate all of the support that they give me because it allows me to make cool videos like this one that do take a lot of time to make all right till next time this has been Nico Carver.

Clear Skies!.