Plate Solving Issues With New Antila ALP-T 3nm Duoband Filter - Forums

Topic starter

Feb 28, 2025 · Edited: Feb 28, 2025

Hi Folks,

I haven't found much on the internet about this issue. I posted on CN this morning and I am waiting for a response.

I am using an Explore Scientific ED102 Essential Series scope with a 0.8 FR/FF so the scope is operating at F5.6 at 571mm.
I image with an ASI 533 MC-Pro camera and use N.I.N.A. 3.1 HF2. I image in Bortle 7 skies.

I have been using an Optolong L-Enhance and IDAS LPS D-1 filters for years using a 3 second exposure time for both autofocus and plate solving (for plate solving, I have the gain set to 400).

I just bought a Antila ALP-T 3nm Ha & OIII Duoband Filter so that I can image more during bright moonlight.

I knew that I might have to make some adjustments to my autofocus (Hocus Focus) exposure time setting and plate solving, but I am having limited success.

I have the autofocus exposure time set to 6 seconds with the Antila filter and it works well so far.

I am having issues mainly with plate solving. I have increased my exposure time up to 20 seconds. Of course, this makes TPPA (polar alignment) excruciatingly slow. I have switched to the IDAS filter just to plate solve, but I really don't like to open up the imaging train (filter drawer) outside if I don't need to. This works for polar alignment, and could work for plate solving, but it would take the automation out of the picture if I had to switch filters to PA at the beginning of the evening, after the meridian flip, and when moving to another target.

20 second exposure time for plate solving works most of the time, but I have had a few failures moving to another target (I figure it is because of a dimmer star field).

I have upped the gain for plate solving to 800, but I believe that the 533 MC-P gain tops out at gain 450. This hasn't significantly helped. Still getting occasional failures.

I did notice that in N.I.N.A. plate solving settings, there is a binning selection (mine is at 1). I have never changed binning with this camera (or any other camera) so far, but I would think that this would be a good next step.

I would think that folks using the L-Ultimate could have experienced a similar issue.

Does anyone have any thoughts or experiences on this? Might binning the camera during plate solving offer some help?

Thank you for any ideas or experiences!

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Tony Gondola

Frequent contributor

Feb 28, 2025

I wonder if it's a mismatch in spectral characteristics between whatever catalog ASTAP uses and the filter. Just throwing things off enough that it occasionally confuses the plate solving?

Jim Raskett

Topic starter

Feb 28, 2025

Tony Gondola:
I wonder if it's a mismatch in spectral characteristics between whatever catalog ASTAP uses and the filter. Just throwing things off enough that it occasionally confuses the plate solving?

Not sure about that. Interesting idea, though.
Thoroughly expect it to be more difficult since the stars are greatly reduced.
Just looking for ideas.
Binning just popped in my head this morning. Never used binning before, and not sure if it will work with my camera.
Thanks for the reply!

Ryan Faulkner

Mar 1, 2025

You can bin with the 533 and it will help.

Does Antlia make a focus filter? I image with the Optolong L-Pro and L-Ultimate and adding the Optolong Focus filter has been a big win for me. The Optolong filters are all parfocal, so I can plate solve with the focus filter, then switch to the L-Ultimate and not worry about changing focus.
I have a filter wheel, but you can do the same thing with a filter drawer.

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Mikołaj Wadowski

Mar 1, 2025

I'm using a similar setup to yours - a 533mc pro, a 3nm dualband filter, and an f4.8 frac.
I use 6s subs, gain 100, and bin1 for plate solving. I suspect your plate solving fails because of very high gain - the stars just clip too quickly and ASTAP can't use them for an accurate solve. I'd set it to 100, the difference in read noise is insignificant. You can also try setting the search distance in ASTAP to a higher number and see if that helps.
Also, quick sanity check:
- Do you have the correct focal length set in NINA?
- Do you have the correct pixel size set in NINA?
- Does your mount think it's pointing to the correct area of the sky?

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Jim Raskett

Topic starter

Mar 1, 2025 · Edited: Mar 1, 2025

@Ryan Faulkner

Hi Ryan,

Thanks for the reply. I would have responded earlier, but just after I read your reply, I saw that the sky was partly cloudy so I fired up the kit.

Since it was late, I didn't cool the camera (ambient temp about 12C) because it was late and quite cloudy.

Still hit and miss at a bin of 1. When I switched to bin 2, I had no successful solves. Just to note though, the images were quite noisy and full of hot pixels (probably because I didn't cool the camera).

Of course, I could have run into clouds that caused some of the failures, but not all. Also, not sure if the warm sensor and hot pixels caused failures at bin 2.

I will either try again tonight, or punt for now and use my L-Enhance since I only have one more clear night and I would like to collect some data.

Thanks again. I will update.

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Jim Raskett

Topic starter

Mar 1, 2025

Mikołaj Wadowski:
I'm using a similar setup to yours - a 533mc pro, a 3nm dualband filter, and an f4.8 frac.
I use 6s subs, gain 100, and bin1 for plate solving. I suspect your plate solving fails because of very high gain - the stars just clip too quickly and ASTAP can't use them for an accurate solve. I'd set it to 100, the difference in read noise is insignificant. You can also try setting the search distance in ASTAP to a higher number and see if that helps.
Also, quick sanity check:
- Do you have the correct focal length set in NINA?
- Do you have the correct pixel size set in NINA?
- Does your mount think it's pointing to the correct area of the sky?

Thank you very much for this Mikolaj!

Very good to hear your experience. Gives me hope!

Wow, your settings are quite conservative! I will try them soon. I am slightly higher at F5.6, but hopefully that won't big a big issue.
I have always used a gain of 400 for plate solving with an exposure time of 3 seconds no matter what filter I was using and it has worked flawlessly for years. I did try 6 seconds at 400 gain to start with (with the Antila) and I had hit and miss solves. I did collect some data the other night on the Headphone Nebula, but my NINA sequence switched to M97 just after midnight (the solve for the Headphone after the flip worked well). When the sequence switched to M97, the solve failed and I missed a half night of data.

I have one clear night (tonight), so even though I would really like to get the solving issue resolved, I am considering going back to the L-Enhance just to collect some data.

I hope to get back to "solving" this issue soon. Since you are running similar equipment, would you be okay with a pm with a question? Or, I can just post to this thread.

Again, a big thanks for this!

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Mikołaj Wadowski

Mar 1, 2025

Jim Raskett:
I did collect some data the other night on the Headphone Nebula, but my NINA sequence switched to M97 just after midnight (the solve for the Headphone after the flip worked well). When the sequence switched to M97, the solve failed and I missed a half night of data.

Sounds like it's most likely not a mount pointing issue then.

Jim Raskett:
I am considering going back to the L-Enhance just to collect some data.

I'd honestly keep trying to troubleshoot the Antila - data from this filter will be so much better it's worth it, even if it means you lose a couple of hours of clear skies.

Jim Raskett:
Since you are running similar equipment, would you be okay with a pm with a question? Or, I can just post to this thread.

Absolutely, feel free to PM me.

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Jim Raskett

Topic starter

Mar 1, 2025

Mikołaj Wadowski:
Jim Raskett:
I did collect some data the other night on the Headphone Nebula, but my NINA sequence switched to M97 just after midnight (the solve for the Headphone after the flip worked well). When the sequence switched to M97, the solve failed and I missed a half night of data.

Sounds like it's most likely not a mount pointing issue then.
Jim Raskett:
I am considering going back to the L-Enhance just to collect some data.

I'd honestly keep trying to troubleshoot the Antila - data from this filter will be so much better it's worth it, even if it means you lose a couple of hours of clear skies.
Jim Raskett:
Since you are running similar equipment, would you be okay with a pm with a question? Or, I can just post to this thread.

Absolutely, feel free to PM me.

Thanks Mikolaj,

Totally get you on keeping on trying with the Antila. I did get a few hours on the Headphone a few nights ago with the Antila and it is really an interesting target.
I might try dropping back on theplate solving settings (maybe start at 6-10 seconds exposure at iso100-200 and if it goes well, I will image the Headphhone and maybe get up late and try running a sequence on M97. If I have trouble solving M97 at least I will have the Headhpone data. I will lose the Headphone soon as it goes into the trees early.
Many thanks. I will let you know how it goes.

Jim Raskett

Topic starter

Mar 2, 2025 · Edited: Mar 2, 2025

Hi Mikolaj,

Well, I just started the N.I.N.A. sequence on the Headphone Nebula.
Following the settings that you kindly shared, I started the evening moving the scope to several different targets and plate solving with a much lower gain (I set it to 100 as you suggested) and a 10 second exposure length. Well, I made no further adjustments and solved 15 times without a failure!
Overthinking things got me in !rouble,

I knew that the filter was very restrictive and started testing with way too high a gain setting. I increased the time up to 30 seconds and tried 2x2 binning and things only got worse!
The solved 10 second images are clean and the stars look bright.

I appreciate your help tremendously!!!

Edit: Session completed with multiple targets and no plate solving failures!

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Dan Kohn

Mar 18, 2025

Ryan Faulkner:
You can bin with the 533 and it will help.

Does Antlia make a focus filter? I image with the Optolong L-Pro and L-Ultimate and adding the Optolong Focus filter has been a big win for me. The Optolong filters are all parfocal, so I can plate solve with the focus filter, then switch to the L-Ultimate and not worry about changing focus.
I have a filter wheel, but you can do the same thing with a filter drawer.

I have the Antlia, and do not use it during PA and rough focus steps, it blocks too much of the light. I put the filter in as a last step once PA is complete, guiding calibration complete, and I have slewed to target. Then will do fine focus with the Antlia in place as last step before imaging. Recommend getting a filter drawer to make this process less of a hassle.

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Geert Vanhauwaert

Mar 18, 2025

Hello
Since you're working with N.I.N.A., you should be able to choose between several image resolution algorithms (programs).
Which one are you using as your primary method and which as a backup?
Have you tried taking an image manually with parameters similar to those used for resolution, and trying to resolve it manually in N.I.N.A.? or externally to N.I.N.A., that is, directly with the program you use in N.I.N.A.?