Bigger scope for Jupiter imaging or dedicated cooled astro camera for DSO

andrea tasselli · Apr 27, 2026, 06:12 PM

Unless you live in the tropics I’ll opt for the camera,

Thanks Andrea.

Tomorrow, I'll have one last opportunity where Jupiter will be around 36° altitude, just when it’s dark enough, but critically, Callisto will be around 10’ from its edge. I’m going to target focus on this moon, drop gain back for Jupiter, don’t refocus and we’ll see what happens. Possibly my last chance before conditions become too poor. Forecast is actually for clear skies too! The stars are aligned. Just need to avoid screwing things up.

Jeffrey Kieft · Apr 27, 2026, 08:50 PM

In regards to planets and detail, this podcast featuring Daniel Mounsey is really worth listening to: https://podcasts.apple.com/us/podcast/the-observers-notebook-seeing-and-transparancy-with-dr-d/id1199301885?i=1000758651935

While it focuses on visual observing, it has great insights into seeing vs. transparency, the effects of tube currents, temperature gradients, etc. and the dramatic effects these have on observing details in planets. One point he makes is that larger aperture is not always better, because bad seeing effects are amplified. He points out how things like shooting over a rooftop or a parking lot a few blocks away vs. over a body of water, how your scope is stored, etc. can make more of a difference than your aperture.

Anyway, it was kind of an eye opener for me.

Thanks Jeffrey

I’ll certainly be listening to that podcast. 👍

Rick Evans · Apr 27, 2026, 09:46 PM

I’m not a very proficient planetary imager but I have had a lot of experience this past year using many different scopes and cameras on Jupiter. I don’t really travel anymore and live in a region with perpetually poor seeing. I’ve used everything from 4 inch to 12 inch aperture and various scope designs. I’ve also used most of the more common planetary cameras.

Unless you have access to at least 3/5 seeing on a regular basis I am skeptical that aperture rules. Many will say that lucky imaging technique, done well, can largely overcome seeing problems. My experience is that while this is true up to a point, it was never possible for me to turn 1/5 seeing or 2/5 seeing into a remarkable image of Jupiter.

In my skies I am mostly content with 6 or 7 inches of aperture. For example, although I have my 12 inch scope ready to go… I plan on using a 140mm refractor tonight on Jupiter since seeing is forecast at about 2/5. I think the best you can do is to match your camera sensor pixel pitch to the F number you are imaging at. I think the most used formula is 5*sensor pixel pitch should approximately equal the f number you are imaging at. Another important point in my experience is that when you multiply your frame rate by your exposure time in frames per second, the result should be as near to 1000 as you can get. I am also careful to leave the gain a bit on the dim side to avoid overexposing highlights.

Also, I think a planetary camera is better than a cooled camera. Frame capture rate and many camera parameters in planetary cameras favor imaging something like Jupiter while cooled cameras tend to excel at deep sky objects.

Rick

Thanks Rick.

Very interesting experiences! Tomorrow i’m planning on an alternative approach, because calisto will be near disc of jupiter, and i’m planning to go for focus on that moon, not on jupiter. I’ll have a 15-30 minute window.

I think my exposure an frame rate is OK, around 4-5ms and 250fps.Gain around 250. It’s my focus i’m not convinced about.

The comment about the Asi533 was whether I should commit my budget to that, as i’m also interested in dso too, or put the budget towards a bigger aperture. But i’m getting the feeling, that could be unwise,if indeed, seeing is never good enough.

I need to at least be sure i’m doing the best I can with my 250pds though, so i’m seeing-limited, not equipment/ability - limited.

Thanks

Best wishes

Mark

Tony Gondola · Apr 27, 2026, 11:16 PM

Mark Worthington · Apr 27, 2026, 07:05 PM

I'll have one last opportunity where Jupiter will be around 36° altitude

You really can’t get diffraction limited images of the moon or planets at such a low elevation. Both seeing and atmospheric dispersion will bite hard. I really wouldn’t bother.

With nearly 10” of aperture you can get good images if:

Your seeing is very good.

Your optics are perfectly collimated.

The subject is high in elevation, preferably >60 degrees.

Your sampling is correct (imaging F/ratio should be 5 to 7 times the camera’s pixel size)

You use proven lucky imaging techniques.

Even with all that, the subject really benefits from larger apertures. The best images seem to come from apertures in the 14 to 16 range, under excellent seeing conditions.

Thanks Tony,

To answer the points in order,

Not sure on seeing last time, but was able to crank up mag to 300x without mushy view for once, 40° altitude, f/ratio to 2.9 micron pixel size was 3.6 so undersampling, 15000 frames, 4ms, 250fps. But, i’d still expect to see features like festoons appear, albeit small.

Best wishes

Mark

Tony Gondola · Apr 28, 2026, 12:28 AM

40 degrees elevation is too low, even if the seeing in good. Planets and lunar hard, you’ll shoot many sessions before everything lines up for you. You do need to stack the odds as much as you can.

Thanks, do you have any experience of adc to partially compensate for lower altitude?