ZWO ASI Air Tutorial: Autoguiding & Dithering

hey everyone today's video is going to be another tutorial on the zwo asi air the topic of today's tutorial is going to be how to auto guide and how to dither using the asi air now not only is this super easy to do it's also extremely effective if you want the most crisp sharp long exposure astro photographs you definitely need to auto guide and dithering is also a major plot and they're both very easy to do with the asi air so hopefully by the end of this video you're seeing great results auto guiding and dithering using the asi air and producing some awesome images of your own so without further ado let's jump right into it [Music] now before you start auto guiding you need to determine how you're going to connect your guider to your mount now there's two main ways to do this there's an old school way which is the way i use using the st4 cable or there's a modern way and that's using the usb cable and they both have their advantages and disadvantages the st4 cable the big advantage is it's extremely simple it's time proven i can't really get it wrong plugs into the guide camera and then typically goes into the auto guide port on the mount and that's pretty much it very very simple but it does not give you much advanced control over the mount like the usb cable does so this one's a little bit more complex but it does give you more control over the mount so this one typically plugs in to a hand controller which goes directly into the asi air this is going to give you control over more advanced features now a lot of astrophotographers nowadays will also say this is a more effective and efficient way to auto guide with better results i don't really see the difference a whole lot i've used both and i just stick with this way because it's really really simple and i don't really use the advanced commands on my mount very often so either way it's personal choice use whichever you want but either way should work out no problem make sure you have a good polar alignment before you start auto guiding the better your polar alignment the better your guiding is going to be and that's especially true for long focal length telescopes in fact it's essential you need a good polar liner lower focal length telescopes are a little bit more forgiving but in general the better your polar alignment the better your guiding results you'll also want to make sure your mount is well balanced so that when your auto guider is sending commands to the mount it's not getting bogged down and it can catch up and everything runs smoothly so balance is key and polar alignment is key so that being said i'm going to go ahead and balance my telescope i'm going to polar align it and i'm going to get it on my imaging target and then i'm going to start the auto guiding and dithering sequence in the asi air app and just one final tip for you if you're using a guide scope don't forget to take off the dust cap i've done this so many times and i get so frustrated with myself and like hey i can't see anything what is going on 20 minutes later oh the dust cap is still on oh it's such a frustrating thing but it's so easy to do so if you're using guidescope just make sure this is off all right so i just finished polar lining on deshuba which is above antares in the constellation scorpius and the polar alignment is right on the money so auto guiding should be pretty easy from here okay so with that great polar alignment i am now ready to begin auto guiding the first thing i did was take a test exposure of my target just to make sure i'm focused and everything is looking good so this is the pelican nebula it's ic5070 and if i tap on my main camera tab here you can just see what i'm using this is the asi 294 mc pro the telescope is the celestron 8-inch transits that has a 400 millimeter focal length i'm using 120 gain and the cmos is being cooled to negative 10 degrees celsius so that being said the image looks pretty good so far the polar alignment looks good so i'm ready to begin guiding so i'm just going to direct your attention over to the left you'll see the guide button here now you're not going to use this right now but it will be important later so that's why i'm showing it to you you can see that dithering is turned off for now so i'm just going to tap that and get rid of it and now you'll see the guide settings button at the top and that you're going to tap on and this is actually going to give you all the settings that you need to guide so the guide camera i'm going to pick the zwo asi 178 mm now obviously the 294 mc pro is grayed out because it's already in use as the main imaging camera so i'm going to tap on that and then don't forget to turn it on over on the right so tap on that okay great the guide scope focal length is 210 millimeters because i'm using the stellar view 50 millimeter guide scope you want to make sure that that value is accurate uh gain settings for guiding well some people say you know you should go 80 to 90 percent of your guide cameras gain or 10 to 20 percent i found that kind of right in the middle or just below the middle is fine so i'm using 200 gain the calibration step is 2000 milliseconds the max deck duration is 2000 milliseconds and the max ra duration is 2000 milliseconds now i'm going to pause the video real quick and interject a few of my thoughts in the time that i've recorded this video i've realized there's some mistakes in here and the first being the calibration step at 2 000 milliseconds that's probably too long for most users that's what the default setting is when you get the asir so i would recommend switching that down to about 400 or 500 milliseconds if you feel like you need to increase it you definitely can maybe 600 or 700 milliseconds but 2000 milliseconds is probably just a bit too long and the same goes for the max deck duration and the max ra duration those should not be 2 000 milliseconds 300 to 400 milliseconds is uh probably a much better setting for most guiding setups so when i made those changes to 300 milliseconds on on my max deck and max ra durations my guiding results were significantly improved uh both axes before at 2000 milliseconds were roughly 1.5 arc seconds after i made those adjustments they're now about 0.5 arc seconds in both axes so much much better it's important to remember that you know the phd in the asi air is a light version so you don't have access to all the settings but you do have access to the main settings it's also important to remember that each night is going to be different so you may have to adjust your settings depending on where you're imaging you know if you're more towards the zenith or more towards the horizon you're going to have to change up your settings so luckily the asi air makes it really easy to do that so yeah that is just a brief interjection and we'll continue with the video now an auto restore calibration i think it's fairly obvious what that does and then dither settings is what i'm going to tap on next so what is dithering exactly well dithering is a really easy way to remove noise from your images using your auto guider i have my auto guider setup to move my field of view 3 pixels in a random distance and direction every image and what that will do is characterize the noise so what do i mean by that well if you tell your auto guider to move the image by three pixels you would expect all the pixels to move by three right well some don't and those pixels that don't move are noise so called dead pixels or hot pixels and because you characterize that noise by dithering the image it can later be removed by your stacking software so basically dithering works hand in hand with dark frames to remove noise and make your images even more crisp so with that being said i'm going to go ahead and turn that on over on the right don't want to forget to do that i have it set to move my image is three pixels like i said some people that do ultra wide field imaging do 10 but for this wide field setup three should be just fine stability is in arc seconds and that's basically how close do you need to get back to your guide star before guiding resumes so i've set it to two arc seconds three arc seconds honestly wouldn't be a bad choice for this setup either the settle time is five seconds that's what i have set and that basically is how long the guiding needs to be stable after dithering for you to start your imaging again and then interval is how many images do you want to dither basically so if you set it till one you're gonna dither every image and that's what i do it takes a little bit longer but i found it's worth it you know if you only want to dither every five images put five right there and then ra only obviously means to guide in right ascension only so i'm just going to tap back now okay so now the guide settings button at the top is highlighted as you can see since we turned on auto guiding and now if you tap on the guide button at the left you'll see that dithering is also turned on so go ahead and tap on the graph now and this is going to pull up the guide menu now make sure the dust cap is off of your guide scope otherwise you're not going to see anything and then go ahead and tap the looping button now notice the asi air picks the best guide star automatically now you're going to want to make sure you don't pick a star that is too dim if you pick a star that's too dim you're going to lose it and find it and lose it and find it and your auto guiding performance is going to be pretty poor throughout the night likewise you don't want to guide on a star that is too bright remember the whole point of auto guiding is to measure the brightness of a star and move the mount accordingly if you can't measure how much that star is moving then auto guiding isn't going to work so well so this star in the middle here looks pretty good so i'm just actually going to keep that i don't see a reason to to move that and then you'll notice if i tap on the start guiding button i'm going to get an error so i'm going to tap on that now and notice it says all equipment must be connected first no matter how many times i tap on that so you may be confused thinking you know i do have all my equipment connected why isn't this working well if you look at the top there's a telescope and mount icon that is not highlighted that also needs to be turned on so i'm going to tap on that now and that's going to bring open the telescope settings now i'm using the st4 cable tonight as i mentioned if you're not and you want to use more advanced controls just find your mount and connect that way but for simplicity's sake for this video i'm using the st4 i'm going to now turn that on go and now when i come back i can go ahead and tap the guide button and it will start calibrating and just like that guiding was quickly established you can see my numbers are looking pretty good so far they usually fluctuate quite a bit within the first minute and then start to level out a little bit but i've decided to go with two second exposures tonight in general the consensus is anywhere from two to five seconds is pretty appropriate for auto guiding as you do get closer to the zenith you may want to reduce your exposure time a little bit but for this case two seconds is is what i'm going with what's also nice too is you can increase or decrease the aggressiveness in both axes if you need to do that okay so i'm going to go ahead and pause the video and interrupt myself again but when it comes to declination aggressiveness and right ascension aggressiveness you really need to look at the graph in the numbers if your graph and numbers are really jumpy you're probably over correcting or over guiding and you'll want to decrease the aggressiveness in whatever axis you notice the problem in and the same goes for under correcting or not enough guiding if you don't see very many changes and your your numbers are aren't that great and you need to increase the aggressiveness you certainly can do that so it's kind of a game that you just have to play you just have to adjust things until you you get it right and you know theoretically you shouldn't even need to auto guide in declination you should only need to auto guide an ra but this is not a perfect world so we do auto guide in deck but really you should work on refining your right ascension as much as possible and getting it as good as you can so with that we'll go ahead and get back to the video and really you're getting most of the functionality of the computer-based version of phd in the asi air it's just super super simple so we are guiding now i'm going to go ahead and tap back can see now the guiding button is overlaid on the main screen and you get all your numbers here and your graph so now i'm ready to image so i'm going to go ahead and tap on the preview tab and switch this over to auto run then i'm going to tap the 0 out of 30 here so it's ic 50 70 120 second lights i'm gonna take uh 150 of these what's 150 120 that's 300 minutes okay so five hours so yep i'm gonna take five hours group by slot yes meridian flip so this feature is super super cool um when performing a meridian flip it will stop guiding it will flip and then it will start guiding again on the same star for you now i will say this if you're using an st4 cable this feature probably will not work you're going to need to use the advanced commands on the mount that other connections are going to give you so if you're using sd4 don't expect the meridian flip flip feature to work and then shut down asi air you know tap that so when you're done with the imaging session the asi air will automatically will automatically turn itself off so now i'm going to hit back guiding is looking decent you know not amazing but totally sufficient for two-minute exposures even five-minute exposures i think this would be just fine so i'm going to go ahead and start my imaging run i'm gonna get a message that asi air will power off after finishing because that's what i selected so yes that's fine confirm and i'm gonna let it start going here and we'll check and see how it did okay so 15 seconds away from the first exposure being completed here uh the guiding still looking pretty decent not the best in the world but good now notice right as the exposure finishes here the bottom left of that graph it says guiding it's gonna switch to dithering dithering now settling it's 5.7 arc seconds it needs to be within two remember to to start the settle so it's doing that now okay and it's waited for five seconds awesome it's done and taking the next exposure so basically what that was doing is it was settling out for five seconds within that two arc second specified range before it started again and you can see that on the graph the dither right there and things are coming back down so yeah this looks really really good the image updated everything is looking nice if i zoom in here look at the stars they look nice and round so yeah these look these look really really good so i'm going to let this go ahead and run for five hours auto guide for five hours and dither obviously after each image and then go ahead and see the results i'm expecting to get a pretty decent image all right let's check out these stars and see how round they are after two minute exposures so i think the stars look pretty good if i zoom in here and check them out they're all looking pretty round to me you can see that the auto guiding was really effective even for two minute exposures it's pretty necessary to auto guide to get those round sharp stars and it becomes even more necessary the longer your image duration goes if you want to expose for five minutes auto guiding is basically a necessity at that point auto guiding is also very beneficial for long focal length telescopes where guiding errors quickly become apparent so overall the stars look good exposure after exposure the stars are round so i think the asi air shows that is more than capable of guiding your mount and allowing you to do quality astrophotography [Music] [Music] all right well i hope you enjoyed this tutorial on the zwo asi air on auto guiding and dithering you can see it's a pretty simple process and is capable of producing some pretty amazing images so again i hope you enjoyed this video thanks so much for watching and clear [Music] skies you

Channel: AstroBlender

Views: 81,367

Keywords: ZWO, ASI, Air, Pro, ASI 294MC Pro, Celestron, AVX, CGX, CGEM II, Astrophotography, Astronomy, Telescope, Nebula, AstroBlender

Id: Ae4iGj1GcB0

Length: 17min 35sec (1055 seconds)

Published: Thu Aug 13 2020