Dithering with a Star Tracker and DSLR

[@3082frank]

One of the main reason I enjoy Peters astro photography tutorials is because he explains it really well and he uses affordable equipments for us beginners..who cant spend thousands of dollars towards starting astrophotography as a beginner. Great job...

[@astrophotonics9470]

When it comes to covering and using grab & go rigs Peter is the best on you tube. Good job Peter.

[@frackcenturion]

🔭👍

[@stevenrobinsonpictures]

Peter good video generally. That said should be stated though you do not need an ASIair pro to get this to all work, and also you can dither without guiding at all. I do it on my star adventurer using the app. I simply connect the DSLR into the SNAP terminal, wirelessly connect to the star adventurer and control everything from my phone. Do not know if the sky guider has this option but easier than a lot of the extra things you are doing if you aren't guiding and just want some basic dithering which I find really helps image quality.

[@dougiesmart1623]

A most splendid video there where I took a few notes. I suppose you may have got more out of your configuration by doing 3 minute lights and only dithered every 3 or so subs. By doing this, I find that less time is wasted with dithering, but still keeps the benefits of doing it. I really enjoyed your video, but if I am taking just 60 second subs, I don't bother with guiding at all as I found with my set up that it makes little difference. Certainly you included a very clear caveat that peoples setups, equipment and conditions will vary and so one size may not fit all so to speak. Keep up the great videos 👍

[@BassTime]

One thing i couldn't help to notice about the comparisions, was that it didn't do dithering the justice that it does. You mentioned how it takes almost 30 seconds for the image to stabilize to allow dithering to continue. What i find wrong about this, is that you mentioned that you could have pushed your exposures to 3ish minutes without trails. If this was the case, this would have allowed you to take a lot more subs compared to a 1.2 minute sub. If all went well, you would have captured around 45 minutes of good data rather than 30. In the long run, it does make a huge difference and especially for me, walking noise has been a huge issue and i've been forced to dither manually (i prefer to do it every 5 shots and it works like a charm). Anyways this video is still very informative on the concept of dithering and i'm glad you made it :)

[@RimantasLiubertas]

And you can dither every other or third or fifth frame.

[@BassTime]

@@RimantasLiubertas Yeah i mentioned that

[@maxmayer6009]

I get terrible walking noise without dithering but the improvement from 1.5h to 3h is Night and day. Even without dithering on the SkyGuider pro with eyeballed polar alignment on the Southern Hemisphere. After seeing this, I abandon my endeavour to find a ditherbox for the SkyGuider. This is my mobile widefield rig and it’s meant to work off its own batteries without 12V in the field. I messed around with too many 12V batteries and laptops in the field. It just doesn’t last. Dithering was the one thing to combat walking noise but exposures en masse rule! The rest is noise reduction and still yields far better images. You have proven this properly. So I rest my case.

[@billblanshan3021]

Thanks for the video Peter! I would recommend dithering every 3 to 4 exposures, especially when you plan on shooting lots of exposures. I've never used ASIair but it would be cool if they monitored star HFR and gave you a warning if the HFR changed a curtain percentage so you knew when to refocus. NINA software does this, very nice feature.

[@cucubits]

I wouldn't recommend paying for an Asiair. Essentially it's a glorified raspberry pi. You can just buy a raspberry pi board and put free Astroberry on it. It comes loaded with lots of software and you can connect to it via wifi from your phone/tablet. It's a bit of a hassle to get it right but you don't get anywhere near the cost of an asiair and it does have way more features. Yeah, NINA is awesome!

[@clarky_astro]

I would definitely recommend ASIair Pro. It’s not expensive and works straight out of the box, first time, no messing. Sure you can do what cucu says above, but for me it’s worth an extra few pounds for the ease of use. It’s not expensive anyway. ZWO are a very customer-centric company so the updates do reflect customer feedback pretty well. (If you’re a more advanced astrophotographer that needs more functionality than ASIair Pro, you’re unlikely to be watching this video for the basics of dithering on a SkyGuider Pro)

[@IcedReaver]

As of 28th Feb 2021, the ASIair has a new setting in the dithering menu called "timeout". This is the maximum time you allow the ASI to wait for stability before ploughing on with images. I found that even though I had really good tracking with my Star Adventurer, it would not start taking the next image while dithering as the default setting was 99,999s. I set this to lowest value of 30s and everything is fine. My subs are 300s in length so I'm happy to wait 30s for dithering between images. Of course, if your subs are 30s in length then I can see why you may not want to dither. I've been shooting the rosette nebula and even with darks, I see a lot of banding across the images with my redcat and Canon T3i. Only dithering can eliminate this.

[@cucubits]

The comparison at the end is not fair. Dithering does help. Anyone looking for proper information on this, please do some more research, watch other youtubers as well. Dithering is very important and it will make your images better. There are ways to shorten the "wasted" settle time, for one, I would not recommend the AsiAir. Look into Astroberry, or a windows mini PC, there are many many other ways to skin this cat and what's presented here, is definitely not the best option.

[@adventureswithfrodo2721]

The problem is you have someone that is producing KZbin video to convince people to buy his poor classes. This is a poor video as usual.

[@cucubits]

@@adventureswithfrodo2721 Very true. Some of his videos have useful info but the constant plugging of his overpriced courses are a huge turnoff. Instead of this approach, he'd be way more successful if he focused on quality videos and increase his sub count.

[@MarkoPola]

Another option for anyone looking for a compact sky tracker there is also the skywatcher AZ Gti and it could be configured to equatorial mode. This mount has go-to function and can track in both axis. Makes it easier to find your target and could make your dithering more effective. It is similar cost as the star adventure. Very compact too.

[@ArtemDjesmedjyan]

Peter, I always like your videos. It's comprehensible indeed and it's a pleasure to listen to a tutorial recorded by a knowledgeble person. It would be really great if you also cover dithering with SAM as well. Another reason is that SAM (providing it ihas version 3.10 firmware or newer) actually has this option readily available and also mobile application that has all necessary for this. Unfortunately it has almost no explanation on the input parameters for dithering mode - so that would be really great if you could cover this in a separate video. Thank you for your videos and good luck in star hunting!

[@stevenrobinsonpictures]

Yes you do not need to guide to dither. With the console just try 2 and leave a space of 15 seconds between each photo for the mount to settle. I find that works but it will involve trial and error based on camera, lens etc.

[@robb7342]

I would think that dithering with a 600mm lens and guide scope is pushing the load limit of the IOptron, hence a possability as to why it took so long to stabalize. Something you noted a few times in the video. That being said, a great overall presentation with lots of information for people like myself just getting started.

[@tekn0lust]

Perfect Timing. Just planning an M31 session with my Z61ii and a DSLR on a Star Adventurer.

[@avananana]

I do think dithering is made for really long exposures, 3+ minutes, due to the lost time. The 70sec exposures don't really have a lot of time to gather data which means that the 30 seconds you spend dithering makes a 100-second exposure contain only 70 seconds of data, that's a bad dither-to-data ratio, if that's even a thing. Not here to guilt trip your or anything like that, just saying that I don't think it was a fair match. But then again, star trackers are so dependent on nearly perfect polar alignment for really long exposures and that creates a problem of course. Great video, gonna try it if I ever happen to get an ASIAir unit.

[@Blacktiecinema]

Not too sure but it looks like you left your dither settings on the default 2000ms... If that was the case, it might take too long.

[@cherylwilcox9648]

Hi Peter, just got the ASIAIR Plus (have not used ASIAIR before). Also got the 120mm guide scope. I am using a SkyWatcher StarAdventurer tracker. Got that connected with the ASIAIR Plus thanks to help from this video, but my Nikon D7500, which shows as being compatible with the ASIAIR Plus, isn't being recognized by it. I bought the ZWO External Shutter Release Cable for ASIAIR-Pro/Plus for my Nikon camera and have it connected - but the ASIAIR Plus doesn't see my Nikon. Suggestions?

[@elbagre71]

Hi Peter, great video thanks. I have my Zwo Asi1600 pro monochroma camera and with an adapter I connected my Canon telephoto lens to the filter wheel and all this mounted on a Sky Watcher Star Adeventurer. Do you know of any software that allows me to dither with that set up? I want to avoid having to do it manually. Thank you. Clear skies.

[@GTheoMedia]

Awesome info my friend! Lol funny thing , apparently I was doing the dithering method without even knowing it :). I have been using the Vixen Polarie (1 axis) star tracker and at a 800mm every 35-40 minutes or so for example Andromeda goes out of my view point because it moves away and every celestial object would always move a little and I would have to re-center the photo every 40 minutes or so. This is the way I have been doing it. I've been planning to get a 3 axis star tracker just for this reason - to have the object centered and not move away for the whole night straight. Will that destroy the dithering process ? I am using the free Deepskystacker and photos come out extremely crisp. Cheers:D

[@RalphBidner]

You can bring your image to da new level if you dither... but only on mounts with two axis (RA/DEC). On a mobile star tracker you get more walking pattern noise while dithering in the worst case. Better spend time in taking more sub exposures and calibration frames (Darks, Flats, Flatdarks).

[@PantherSpawn]

For the star tracker 2i, what setting does it need to be on to use with asiair and guidescope?

[@geonerd]

Why does your system take so lonn (30 seconds?!) to settle? I'm using a much simpler method, with an unguided tracker. I'd assume that if I dithered by momentarily 'bumping' the RA, the tracker would pick up where it left off within a few seconds. No?

[@subodhshetty1]

As always - very detailed and Great information. Thanks a lot

[@TheRushOholic]

Hello Peter can u please tell me which cable do I need to connect my Canon 450da with the asiair pro?

[@tvnostalgia7477]

Is it possible to save the configuration once it’s set up? Would be handy to load the config (cameras, dithering settings, etc, etc) on subsequent occasions. Maybe even some kind of macro workflow feature too?

[@marcoformenton7727]

Hi Peter, nice video, I saw you use a Nikon D750, is this Nikon astro modded or not? If Yes wich is the mod you applyed ti the camera? Thank you very much!

[@atrevete_pr4613]

Is there any way to remove those horizontal and vertical lines and all those green, red spot colors..

[@graysonlane8878]

Yes, but it is quite time intensive. One of my go-to fixes for this is to simply create a custom white balance. There should be an adjustment layer in Photoshop that allows you to adjust the tint and temperature sliders to do this. Another thing I do is to go channel by channel and apply noise reduction filters to them. If you open up the channels tab on your image in Photoshop you will see a red, green, blue, and "RGB" channel (all 3 channels combined aka your image). By applying noise reduction filters to each channel, and varying the strength of them for each channel's needs, it really smooths out the background colors in the image making it less noisy and more consistent. Lastly, if none of those options really fix the spots of color, I will try and adjust the saturation of the image color by color, or simply burn large parts of the image so the sky is darker and the color issues are less noticeable. However, if you get to this point I would just throw the image out and try another night as you probably will not get the results you're looking for if you have to resort to those last two techniques. Hope this helps!

[@slarti42uk]

On the iOptron skyguider Pro there's a shutter control connection, but I've not seen this used anywhere I assumed this was to do with auto guiding in some way. Do you have any idea what that's for? I have a Panasonic G9 but not tried using it with the shutter control on the skyguider.

[@MarietaGuitar]

Peter, I've been having issues where the ASIAIR keeps disconnecting from my DSLR (Nikon D5300). Anyone seen any similar issues? Usually happens in location, so I am wondering whether its the cold temperature, or cable (34F-45F for example). It is very frustrating, and I usually end up using an intervalometer for controlling the DSLR, but that is less flexible. Thanks

[@BassTime]

This is such an amazing timing, i was wondering how to do this. Thanks a lot dude!

[@ivarhusa454]

I am a rookie at this. So rookie, I am still waiting for my tracker to arrive. Here's some of what I learned from this video. I have a question at the end. OK. Longer subs increase the signal to noise ratio and consequently less time at dithering, if one chooses. Dithering is significantly less effective when only done on one axis, as with our tracker. Better polar alignment makes always makes pictures better. Check focus regularly, especially if rig was not 'acclimatized' before shooting. Peter told us "YMMV". He layed out every aspect of this test for our use. I welcome others to carry out their own tests that show dithering is useful quality-wise and tolerable time-wise, if you will. Share results! :) Question: Since the tracker can only dither along RA axis, about how many different aiming spots are used? For a hot pixel, even three or 4 'aimpoints' will statistically be enough to remove the hot one. How many pixels need to 'move' (how severe the dither) to kill color blotching or walking noise? I'd be willing to let my dithering routine walk up and down 100 pixels, to get better 'smoothing'. I'm not proud, and I have plenty of pixels around my distant subjects.

[@zhaooskar3178]

hi Peter, recently my friend took a 5 hours long strar photos in order to make startrails. but unforunatly the milkyway was taken inside the frames. do u have any ideas how to remove the milkyway from startrails? thx

[@Tagger12496]

man I just got the skywatcher adventure and I tried to do the polar alignment but I can't see the aim sight in the scope. I tried to use the red light it comes with but it makes the stars disappear

[@Abaunzamarco]

I also struggle with the polar alignment, weird and uncomfortable positions almost every time...be patient and you’ll get there. I dim the red light and also I turn it on/off and make the adjustments...Preparing your eyes is also important, I tend to be in the dark at least a couple of minutes without any lights, then the stars are easier to spot. Hope this helps...

[@itaialter]

Since I'm not guiding yet with my SkyGuider Pro, I ended up doing Manual Dithering: Every 3 exposures, I slightly move one axis (alternating). First I just tap one of the RA buttons slightly, taking more exposures, then I move the DEC slightly, and so on... I've seen a significant improvement because I was battling "walking noise" before dithering, but no sign of that mess since then. This was possible only after I got a better (yet fairly cheap) DEC panoramic head from AliExpress (i.imgur.com/C1J7EBi.png). One of the better purchases I made for my SkyGuider Pro (along with an arca-swiss dovetail). I don't really like the DEC head that comes with the SkyGuider Pro (with the two locking screws).

[@oryanastrophotography3450]

one benefit with the star adventurer is the dec bracket

[@cucubits]

Do you still get walking noise if you dither only in RA?

[@BassTime]

@@cucubits Its possible, not as good as the manual dithering on the RA only mounts

[@MattMiltonberger]

Thank you for the knowledge, Peter! Out of curiosity, have you ever received the "RA Calibration Failed: star did not move enough" error after reaching 60 steps with the iOptron or StarAdventurer? Followed the tutorial and others that are out there, and I keep running into that error when trying to calibrate my guiding with my StarAdventurer. Apparently it's an issue that others have posted about on forums, but I was curious if you had run into that error at all and learned a workaround. Thank you again for the video!

[@PiKapp707]

Do you have enough power / the right power cord for the ASIAir Pro? I have heard that using the wrong cord can introduce issues like this

[@clarky_astro]

Sounds like the mount is not receiving the signal from the guide cam. I would check the connection between the guide cam to the SkyGuider Pro, check that “on camera ST-4” is selected for the mount on the ASIair Pro and that guiding is on (with Dec off). Otherwise, I’ve no idea, sorry. Good luck!

[@chanceg1218]

does anyone know if a Canon EOS RP will work?

[@astropear6294]

Is it essential you have an ASIAir Pro to dither? Can this be done with just APT?

[@astrosrscat]

I dither by using APT and PHD2.

[@benjaminhuang]

Hi Peter, loving your course. Was the camera connected to the ASIAir Pro via a USB cable? I've noticed on ZWO's website the unit has a camera trigger port. I wonder if I could control my Fuji and Sony cameras through that? (For dithering)

[@alistairscobie3196]

I agree with most other comments - a poor comparison due to the short length of your sub exposures making your guiding settling times a greater proportion of the total imaging cycle. If many short sun exposures are what you intend to do, then only dither every 4th exposure or so! Also the long time for guiding to settle down will be to some extent because you didn't bother to get your polar alignment good. Given you cannot compensate in the RA axis, PA is more critical on this mount than of a fully driven one. More time invested on PA would have probably resulted in shorter settling times and more exposure time. Disappointed if this is the message you are giving on your courses.

[@SmilingJ]

How did you attach your guide scope to your l-bracket? That seams like a very neat solution. Can you provide a link or search term? Edit: Looking at Peters blog and the image (www.peterzelinka.com/img/s/v-10/p3641615322-6.jpg) I found the solution: I just have to unscrew the arca-swiss-base (the one with the clamp) from my spare ball head and the screw might fit directly into the mount for the guide scope. The plate itself can be clamped to the l-bracket just as I would normally do.

[@oryanastrophotography3450]

its an arca swiss clamp

[@opponoastos]

No Sony :(

[@GamjaField]

Don't forget to Drizzle at DSS if you dithered your image.

[@aaronhymes123]

I don't have any camera's. I'm looking to get a new Camera that is good for all around. 4k video's, nature/wild-life photography, land-scape photography. these are thing's i KNOW i will be doing. however i am highly intrigued with astro-photography. seems to me that you need to invest heavy on the Astro side of things to get good results. that is why i am considering getting the Canon EOS Ra!?? thanks. this will be my first heavy investment in a camera. i want to make the right choice. Would LOVEEE to get Camera suggestions to fit all the above needs and still be good for Astro. budget for camera body 2-3k

[@Dntblnk90]

Just get the canon r6.

[@stef2499]

I dont think ur supposed to dither on short shutter speeds. I heard anything more than 5 mins probably SHOULD be dithered. Below probably best to gather more lights

[@dedskin1]

Dithering really needs RA and DEC. Also i used to think like you , i dont want to waste my time , HOWEVER , for some reason , cant really say what it is , i expected PHD to need to Recalibrate after moving , but it really doesn't , literally in 10 seconds its off to another image , so i lose nothing , i had it pause after image is taken anyways . ANOTHER POINT . You should really give your Camera time to Cool off after shot , if not your noise is going up , if you dont have cooling , so even if your DELAY after Dither is 1 minute , you should wait that minute ANYWAYS . SO , i know this is for RA only setups , but im on HEQ 5 PRO, i must add that PRO, becasue im a PRO you know :) no im not , its utter BS , but thats how its called , so anyways , Dither is no brainer for me , i dont waste time with it , not at this setup of mine .

[@MarkoPola]

Zwo posted an updated list of supported DSLRs/MLs for version 1.5 of asiair. It’s in public beta now. facebook.com/groups/ASIAIR/permalink/1774747986021750/

[@Talalpro_1]

Dither is a must to my camera

[@gloomiehoodie]

Geee, by time I finish doing all of that, the sun is already out.... :/ Ouchphotography...you invest tons of money + tons of hours = divorced and broke

[@Zak_McKracken]

"Dither or die", that's what we've found and discussed (to death) already in 2010. If you are not able to dither correctly, or to measure and compare two master pictures-you simply are on a good way so far, but have to learn some more important things. Guessing in Lightroom or Photoshop is not equal with measuring the noise levels in a stacked frame. But you can guess by eye that your dithered image with the same master-exposure time is better. Comparing different exposure times is not scientific at all, but maybe "practical" for you. But you can't get a general conclusion out of this. So I don't understand your conclusion that dithering is not worth the time at all. It would only make sense if you would say "I'm not able to dither, haven't the proper equipment to do so, and also not able to measure the difference in the final noise levels-so I don't see a benefit for me in dithering or not. You don't have to take darks, but dithering is crucial. And since 2010 the detector physics doesn't change so much that we already have flawless, noise free camera sensors. Think as an astronomer if you want to take good deep sky pictures, not as a photographer.

[@adventureswithfrodo2721]

You really need to learn to use your equipment if you are going to ask people to buy training from you. Sorry but if your selling information please offer valid information.

[@Dntblnk90]

solid troll, glad to see you're actually posting the information he missed rather than just trolling.. hope you feel good about yourself