Help needed for dithering with NINA!

First thing, don’t reuse old flats, that’s bad technique. all other calibration frames can and should be reused but dust can move around form session to session so flats need to be done with every session. I’m not sure what’s happening on the noise. It looks like a combination of banding and walking noise. Are you sure you’re not just dithering in one axis?

Tony Gondola · Mar 27, 2026, 12:47 PM

First thing, don’t reuse old flats, that’s bad technique

I have to disagree (somewhat). If your system is being moved around a lot where orientations might change and dust may be lodged/dislodged or if the system is not well sealed or is taken apart and those sorts of things, then yes, you should redo flats.

OTOH, if you have a permanent system that is well sealed and stable in orientations, then reuse of flats can be fine. I actually tried new vs old flats once on my CDK and was unable to see any difference in the calibrated images or in the final result. So like most things, it depends. Sometimes I will only do a new set of flats if I start to see ultra-faint donuts that do not calibrate out.

It often winds up being a matter of what works (or does not work) with your individual system.

As for dither, I always dither and between every frame, both axes, and at least 3-10 pixels. Can you get by with less? Sometimes, but why compromise when it is only saving you 10% or less of your time? Dither on one of my systems (CDK with AO) takes about 30 sec to a minute and on others (unguided refractors) only a few seconds.

Tony Gondola · Mar 27, 2026, 04:07 PM

Bill McLaughlin · Mar 27, 2026, 03:52 PM

Tony Gondola · Mar 27, 2026, 12:47 PM

First thing, don’t reuse old flats, that’s bad technique

I have to disagree (somewhat). If your system is being moved around a lot where orientations might change and dust may be lodged/dislodged or if the system is not well sealed or is taken apart and those sorts of things, then yes, you should redo flats.

OTOH, if you have a permanent system that is well sealed and stable in orientations, then reuse of flats can be fine. I actually tried new vs old flats once on my CDK and was unable to see any difference in the calibrated images or in the final result. So like most things, it depends. Sometimes I will only do a new set of flats if I start to see ultra-faint donuts that do not calibrate out.

It often winds up being a matter of what works (or does not work) with your individual system.

As for dither, I always dither and between every frame, both axes, and at least 3-10 pixels. Can you get by with less? Sometimes, but why compromise when it is only saving you 10% or less of your time? Dither on one of my systems (CDK with AO) takes about 30 sec to a minute and on others (unguided refractors) only a few seconds.

It’s the old saying “everything is great until it isn’t”…..;)

Come on, Tony.

I’d expect better from you. My experience has been I can reuse my flats for many months even. And others I know do as well. No ill effects.

Can you actually back up what you are saying?

Note: I do use a flat panel, and NINA’s Flats master which is a really great way to do registration files.

Tony Gondola · Mar 27, 2026, 04:28 PM

SonnyE · Mar 27, 2026, 04:18 PM

Tony Gondola · Mar 27, 2026, 04:07 PM

Bill McLaughlin · Mar 27, 2026, 03:52 PM

Tony Gondola · Mar 27, 2026, 12:47 PM

First thing, don’t reuse old flats, that’s bad technique

I have to disagree (somewhat). If your system is being moved around a lot where orientations might change and dust may be lodged/dislodged or if the system is not well sealed or is taken apart and those sorts of things, then yes, you should redo flats.

OTOH, if you have a permanent system that is well sealed and stable in orientations, then reuse of flats can be fine. I actually tried new vs old flats once on my CDK and was unable to see any difference in the calibrated images or in the final result. So like most things, it depends. Sometimes I will only do a new set of flats if I start to see ultra-faint donuts that do not calibrate out.

It often winds up being a matter of what works (or does not work) with your individual system.

As for dither, I always dither and between every frame, both axes, and at least 3-10 pixels. Can you get by with less? Sometimes, but why compromise when it is only saving you 10% or less of your time? Dither on one of my systems (CDK with AO) takes about 30 sec to a minute and on others (unguided refractors) only a few seconds.

It’s the old saying “everything is great until it isn’t”…..;)

Come on, Tony.

I’d expect better from you. My experience has been I can reuse my flats for many months even. And others I know do as well. No ill effects.

Can you actually back up what you are saying?

I can back it up from experience. I try to be as clean as possible, when putting the image train together. To setup all I do is gently hand carry the OTA to the mount and I do not open up the filter wheel or the imaging train often. Even at that, I have been bitten when trying to reuse flats so I don’t do it. With setups like Bill’s, yes it can work a lot of the time but I think it’s bad advice for beginners.

Fair enough. But they don’t have to listen. I used to always collect fresh Darks, Flats, and Bias’s every night. Until I tried the dark side of using library files for my stacking.

I keep my imaging train together from the lens to the camera’s fan. Threaded together, fairly sealed. So contamination is very limited in possibilities. And I don’t “tear down” my mount, just cover it, with a ventilator under to draw out any dampness left over from the night, or the heat we get here during many days. (But I don’t cover it before it has dried if it got dewy.)

When I was younger I use to mount and dismount my telescope from the clamp up and carry it indoors during the day. Now that I’m older (and more arthritic) I tend to not do that heavy lifting. (Last time I took the telescope off I got the 25 YO Grandson to do it for me.) But by leaving things setup and together I’ve streamlined my start-ups and shutdowns, and don’t have to fuss with the PA or other mundane tasks of a mount-in-motion. (Like leveling…) Narrows down the things that can go out-of-wack.

TiffsAndAstro · Mar 28, 2026, 07:02 PM

I do a middle, lazy ground

I have a library of darks and bias.

I take flats, but after an hour or so, I check stack my subs in siril. If those previous flats still seem ok, I drink beer and go to sleep.

If they don't look great, I'll drink beer and go to sleep, but set an alarm to take new flats

I drink a beer, put on my CPAP, and go to sleep. LOL! 😉 🤣

I used to include a dark filter in Pos 8 in the NINA routine at the end of every session. I figured the camera was at the same temperature the lights were taken at, so shot a set of Darks followed by the fast Bias files for the set.

But by that time the lease on the beer had passed (so had the beer), and I had most of a night’s sleep. My trusty telescope having done the programed filter images for that evening.

@SonnyE @Tony Gondola @Bill McLaughlin @oymd @Noah Tingey Thank you guys for all your questions and advice! For dithering with nina I havent ever selected to dither in one axis. But when I was out last It showed me the dithering process, And it was only changing on the Y axis. It was slowly going up and thats it! Never the X Axis. I am dithering at 5 Pixels per 3 frames, There is a setting in the mount dither that says “RA Axis only” But I dont believe I set that! Is this possibly a user issue? And if there are any settings I can change for the dithering to hopefully fix this walking noise than that would be really appreciated! Also, @oymd Yes, There is sadly lots of dust on my camera! Me and my mom bought a cleaning kit and tried as best as we could to clean it off but sadly that dust will not come off! I hope its not effecting my images as long as I do flats!

Clear skies!
- Horriblebaby