ZWO SeeStar Mosaic Mode - Gimmick or Total Game Changer? - Astrophotography on a Smart Telescope

hi everyone welcome back to another video uh today we are in the beautiful island of La Palma Spain very popular with astronomers professional and amateur alike astrophotographers such as myself today I will be demonstrating a new feature of the ZW star which is Mosaic mode this little telescope has become extremely popular amongst amateur astronomers and some Master photographers for no reason other than it is Compact and very affordable the reason it is so compact is because it is a very small structure with an aperture of 50 mm and a focal length of just 250 mm yet it is still able to get a large magnification because the sensor mounted on it is a very small one with tiny pixels as a result of using a very small sensor essentially you're applying the large crop factor so even though you have a tiny focal length and just a small compact telescope you're able to essentially zoom into small areas of the sky if you would like to understand more about how crop vectors and field of view with different sensors and focal lengths work I have done a very in-depth video on this I will link that right here today let's have a look at what we can achieve with this and some natural result of this large crop factor as I mentioned this this little telescope has a tiny sensor which is essentially what we would use for a planetary camera very small pixels very small sensor diagonal this is great for a lot of small objects in the sky like galaxies smaller nebulosities and so on however this has a caveat which is every time you try to image something that is larger than this truly tiny area of the sky you have an issue because you're not able to image it in one now this problem is not unique to the need smart telescopes especially not to the sea star this is a very common problem that everyone's going to run into eventually with whatever telescope sensor combination they have with regular or traditional setups the solution for this is quite clear this is essentially what we call doing mosaics a mosaic is very similar to when you do landscape photography and you want to do a panorama so you want to cover a larger area of the Horizon by taking different frames different different tiles you put them next to each other and then you stitch them together in postprocessing we do the same thing in the sky with traditional telescope we do a mosaic we do different panels we expose for multiple hours for each panel we stack them together and then we stitch them together in postprocessing this works a little differently for these smart telescopes for multiple reasons and so far it has not been possible to do this with the zwc star natively there are some other smart telescopes on the market that have offered this possibility but with the ZW it was not a possib AB ility to do this natively so what people have been doing is try to do the same process that I just described manually for example you're trying to image a large area of the sky such as the signus loop which is really huge in the sky for something like this that can only cover like a ninth of it so people would do these panels stack them together separately and then try to stitch them together in postprocessing and then again there were some more tech savvy people who have developed some proprietary software solutions to automate this whole process but now with the new native Mosaic feature we can do this All directly in the application of the sear so today I will be trying that out and demonstrating how to use that I would like to mention already that Mosaic mode since you're covering a larger area of the sky with the same Optics it's going to take longer if we want to achieve a higher resolution image the sear does have an integrated battery but the battery life is only about 5 hours so that is way too short to cover but the shortest of the nights and especially if you're going to want to do a mosaic you will take many hours I recommend getting something like this if you ever want to travel this is 100 wat hours um which is the maximum that you can take on any commercial flight internationally so we are just waiting for the sun to go down it's promising to be another beautiful night I'm very much looking forward to trying this out I am a beta tester so this is currently not on the App Store version but I believe it is coming out very soon so I'm happy to share with you how how this works and what I like about it and maybe what I don't like about that that much let's get into starting the Mosaic uh without further Ado I will be opening the sear app connect to the telescope we are connected so the first thing we're going to do we're going to open the arm so that it can actually start pointing up it is now slowly opening up the arm I will be going into stargazing mode so that I can move this arm up more manually I will be skipping the first part so I just have manual control of the telescope you can see that this is completely out of focus so I will just be clicking on autofocus this way it will be able to do the plate solving later on the autofocus has been completed now it is time for me to start looking for an object some of these very popular objects that people are wanting to do Mosaic on include the signus loop or the Andromeda galaxy tonight I'm going to go for the latter one I will just search for the Andromeda galaxy in uh the app I will be just searching for [Music] M31 this brings up the native field of view of the Andromeda galaxy and you can see that I can only fit like maybe a third or a quarter of it natively this is why we're wanting to do a mosaic on this if I go into the framing mode I have two sets of controls I have the magnification and I have the rotation magnification essentially lets me set up the size of the Mosaic so this is what is going to then determine the number of panels and how the panels are arranged here I'm just going to go all the way out the maximum field of view that I can get as you can see it doesn't give me an option to change the aspect ratio of the image which is very strange because you're going to put um panels next to each other you could do that in any possible aspect ratio there's no reason to be forced to use this aspect ratio but today zwo is not letting us choose anything else the maximum resolution which they call three times essentially this is a 3X3 Mosaic so it's going to be nine times the size of the Native field of view and then the next control is on the rotation I'm going to zoom out a little bit so that I can see it better and rotate it so that it sits in a very traditional framing of the Andromeda galaxy actually I'm even going to go for something a tiny bit smaller here it's better if I cut out this bright star because that would not look nice at the edge of the screen that is going to look much nicer I'm going to go with this framing with all this setup I'm going to hit go to and the telescope should um go straight onto my object it is now initializing on my target you can see that on the screen I think I'm just going to go out of the way of the telescope here it's better if I stand behind it it is just now taking a second it tells you on the screen it is doing a horizontal calibration in case I didn't manage to level the telescope that has succeeded now it is going straight onto my object now that is still Rising it's going to be passing right above our heads so it is a good Target for tonight what this is going to do now now that it will start shooting um essentially it is not that different from when it's doing regular Imaging so 10c images however after it took a couple of pictures of a certain area of the sky it will just do another go-to and move to a slightly different area of the sky it is working in a different way compared to how we do regular mosaics where we would do one panel and then the next panel and then the next panel next to each other here it works in a different way because we don't have entirely different panels we just have many many many panels that are overlapping with one another so that means that we're going to be sacking them the entire set of many many images over an imaginary grid that is the final Target Mosaic and we're going to be integrating them on top of one another we have found our Target we're doing another autofocus and then we are ready to go okay so we have our first image where we can see that this is the core of the Galaxy you can see that it's not really the entire rectangle it is a rounded rectangle they have cut off the corners I would not be surprised price if it was because of the lack of flat frames they probably have a small amount of vetting even though it is a very small sensor I'm almost sure that is why they do it um this way we avoid having sharp Corners that are darker we are currently at 40 seconds so we are going to be shooting this first panel for a while and then we'll move on to the next panel that has quite a bit of an overlab with this first panel and then we will just slowly move around to finally get to the field of view that we want to have I mentioned that we are constrained to short exposure times because of the field rotation due to the alasm tracking system however we still do have field rotation over a longer period of time which when you're shooting a single image the traditional way with this telescope if you were to shoot for 12 hours you would see that your field of view would rotate a whole entire 180° and you would just have one Circle in the middle that is covered in every single image and everything else would just have less data especially in the corners this is a bit different here because as you are rotating the subframes for each of these mini panels while some of the corners are hanging out from your first panel that will automatically be part of the second panel that you're going to do next um but this is actually a good thing because you are throwing away a bit less data we can see that we have started downloading the next batch of images and you see here that the field of view is stared starting to enlarge it will be shooting all night I will be leaving it alone especially turning off that red light because it is shining straight into it and tomorrow morning uh we will see what comes out good morning I have left the telescope out all night it was about eight hours of pure Imaging time and I have the results throughout the night I took some screenshots to to show you how the field of the Mosaic is enlarging let's have a look at those the first one we essentially just have 26 images then we have 584 images stacked then we have 695 images and then finally we have 1,090 images if we do some calculations 1,090 images of 10 seconds gives us about 3 hours of pure Imaging time this is the amount of Imaging time we have actually managed together over nearly 9 hours which makes you think that it is probably not a very efficient process because while at the beginning when you just start out the center of the Mosaic it is um stacking them as you go as the Mosaic enlarges it takes more processing power to align the images and then it takes the software much longer to stack so you end up with an average of 30 seconds to take and then stack a 10-second image which means that you're essentially throwing away 2/3 of your Imaging time this is still in beta testing I think that this may as well be part of the reason while the whole Mosaic solution hasn't been pushed out into the production version of the application yet because honestly throwing away two-thirds of your Imaging time is unacceptable I'm really hopeful that they are going to improve this let's have a look at the image that came out this is a stack that comes out the entire field of view that I was planning to capture was not even finished after these eight hours and something of Imaging time you see that two of the corners are still missing which I'm not extremely worried about because this is something that I can crop so this is the image that comes straight out of the telescope and then I wanted to compare it to one that I can stack from scratch now registering and uh stacking these Mosaic images is not as straightforward is doing it with the individual images because none of the raw files can be used as reference for the registration so what I recommend using is you get the stack that you get out of the sear use that as reference for the registration and then you register all the frames on top of that so what you're going to want to do is you debar all the raw images in case you're using fix inside you're going to want to set your reference image here which will be the stack that came out of sear add all your target images which will have to be the already debed files and then if you want to make sure that you register as many of the frames as possible you have to enable compute intersections always this will allow the software to only use parts of the reference frame as the part that it's going to try to register each light frame onto and this will make it much more easy for you to get everything registered once you have those images you do a regular integration process with your favorite settings what I really recommend is that you don't try to use local normalization because you don't have a true reference for you to local normalize onto and also I actually ended up using no waiting for the images because I don't want to wait different parts of the Mosaic against one another with that I ended up with this image as you can see the shape of the image is very similar to the one that comes out of the SE star I have processed both images to the best of my ability I wanted to see what was possible so first I process the one stacked by myself once you color calibrate and especially if you remove the Stars to see the background better you will see these little squares or or little corners of the individual frames and that is because we are not using calibration frames in my opinion even if you're using such a small sensor it would be best to use flat frames now the seaster of course takes dark frames but that's not what is going to make your images look better because these are very modern sensors and we are taking very short exposure so the amount of dark current that you have is not the issue here the problem is the vetting that you have that becomes very apparent when you're doing a mosaic as such so you're always going to have these overlaps of the center of one image versus the corner of another image image and then it just has a different illumination profile so I have worked out a way to use uh calibration frames for smart telescope images stay tuned for that I'm preparing a video on that as well for today let's just have a look at what you can do with the images that come out straight from the telescope once you remove these obvious uh gradients in the background you see it's not perfect but it is something that you can realistically work with especially considering the tiny amount of integration time that went into this one thing to consider here putting together the two things I mentioned before one being that it only used up a third of the time I spent taking images and the second that the maximum field of view you can achieve is about nine times the native field of view and well obviously only Imaging one nth of that part of the sky at once if you take an entire night and you image for 9 hours that means if you're only using a third of that time you're Imaging for an effective 3 hours and for each part of the sky that is only one nth of that time that gives you approximately 20 minutes per part of the sky that was exposed that is extremely short so I think that this has to be considered when we're evaluating the results this is also something you should keep in mind if you're planning to do mosaics with a smart telescope using this method it works it is possible but it is extremely inefficient whereas if you were to image the central part of the Andromeda galaxy here with the native field of view in 9 hours you would get 9 hours of integration time which being a very very bright object even with the small Optics of the SE star you could get a decent image here we have 20 minutes of Imaging time for the same area of the sky that is very little even for such a bright object let's compare the results I uh processed the stack that I created I also processed the stack that came out of the sear directly to the best of my ability the only kind of setting uh that I copied from my own stack it was that I registered so that they would have the exact same crop so that they would be very easy to compare we can see that they had already applied some sort of Corrections on the images that went into the stack that came out of the sear we already kind of saw this uh yesterday when we started Imaging that the corners were kind of rounded down and at the time I said well clearly this is because they want to avoid the vetting that is due to the lack of flat frames and clearly it has addressed that issue because we don't see those obvious Corners here that we see on our own stack however it has created this very strange artifact where the core of the Galaxy somehow is already brighter and there's this increased contrast between the dust lanes and the center of the Galaxy that just makes it look like an overprocessed image and it came out like this I mean this is not a raw image that we can work with this is a processed image so we're always going to have an inferior result if we're working on it this way by the way I'm using pix inight but I'm aware that there is a script that you can download also for serial so if you prefer that one somebody has written a script for specifically this use case that should also help with this process I highly recommend doing your own processing because you can see that the results are just much better if you ever did live stacking with any software or if you are using the seasar or any other smart telescope you may have seen that if you have a satellite or a plane or something that goes wrong in the first few frames that is going to stay there and that is because the software is not restacking all the frames every time you take a new frame it just kind of adds the new one to the stack meaning you will never be able to reject those first outliers if they were there in the first place if this happens when you're just shooting a single Target then obviously if it happens in the first few frames you can always just restart it without losing a lot and if it happens later it will automatically be rejected now what we have here is that we keep moving to different areas of the sky this process kind of restarts so if if you take a new area of the sky and then you have a satellite in the first few frames it will not be rejected and it will stay there in the final image and this is why we have the stack that came out of the sear I can see multiple satellite trails and this is also something that you can remove by just stacking the frames yourself obviously this is depending on your personal taste and how you like the process in my opinion the version that was stacked by myself is infinitely better because I was able to get get a more natural looking result out of it so if you're going to want to do these mosaics with the sear I highly recommend doing your own stacks and processing it yourself however I would really keep in mind this extreme inefficiency that I've already mentioned so one part of it comes from the inefficiency of the current software that you're only taking about a third of the time you spent exposed I expect that this will be fixed soon however the part where you are only Imaging 1 nth of your desired field of View at once that will remain there so you have to calculate that if you want to have the same signal to noise ratio as you do on your single images if you want to have the large Mosaic with the nice resolution and the large area of the sky you have to image for nine times as long and if you were already Imaging a whole night for a single image this means Imaging for nine nights and that is just extremely long so suppose that you will take nine nights to take a very nice large resolution image keep in mind that you will have thousands upon thousand thousands of these files you will need some processing power or time and a lot of storage to be able to do this processing yourself if you want to do mosaics over multiple nights I think you anyway don't really have a choice but to do the processing yourself because currently the software is not letting you continue a previous stack that you had started I think that this is something that they could enable if they wanted to and I think that that would make it nicer however currently we're stuck with what is provided and I think that if you want and if you invest some time and effort you're able to get a decent result out of it however you need to spend a lot more time integrating and quite some time also on the post-processing compared to a regular single frame image so in conclusion I think that this new Mosaic feature is very welcome for all users in terms of the cost to Value ratio I think the sear is still a very valid option for somebody that wants to start out electronically assisted astronomy so this gives them a way to so image larger areas of the sky which I think is very welcome I'm sure that the feature will get better over time however all those things that I mentioned before are something that you definitely need to consider before taking these really large mosaics I would honestly try to keep the area to the bare minimum that you want to end up with in order to maximize the actual amount of time that you can spend Imaging for each part of that Mosaic I hope that you like this and I do hope that the software will be pushed out to production so that everyone can try this out stay tuned because as I mentioned before I have an upcoming video on doing calibration frames for the sea star and for other smart telescopes in general I think that that will help make also these Mosaic images a lot better when you stack them yourself and if you have tried out the Mosaic uh let me know what you think in the comments down below do you think this is a feature that will be used a lot are you going to use it or are you just going to keep using it with the narrow field of view where it is very simple and you can just work with the stack that comes straight out of the sea star thank you very much for your attention if you like this video consider subscribing to the space koala Channel thank you very much and clear skies

2024-10-07 13:18

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