Problems with long Exposures and save all frames.

Brille

I still get very large rejection values if I choose 30 or 60 sec exposure time despite exact polar alignment of my Seestar S50 (both values 0.1 or 0.0). Last night at 60 seconds, just 15 frames came out within 2 hours (two of which also had satellite tracks). The yield is slightly better at 30 seconds, but only at 20 seconds do I have hardly any rejects, almost every light is usable. What could be the reason for this, how can I optimize it?
On the other hand, I tend to stick to 20 seconds because then fewer images become unusable due to satellite traces. What are the advantages of 100 x 60 second exposures compared to 300 x 20 second exposures? If I stack them, I basically have the same result in terms of SNR, right? And presumably I also get better results for the PSF with short exposures?
What is still not clear to me: How can I get the S50 to really save all lights, including those with star trails and satellite trails? I have switched on saving all lights in the app - but it still only saves the good lights.

ParadigmShift

Brille Same for me. I'm on a pier, so i know my mounting is overly stable. But I've never had good results with anything above 20s. Even before the 2.5 update. I'd love to be able to use 60s exposures, just for the additional detail that'd be present in a final stack, but it's a stressful gamble. I stick to 20, and I have great results with it. I've always assumed that it's a backlash/gearing instability issue that make 30+ so challenging. Best of luck to you!

Seestar_S50

I have the same issue after 2.5 update, the reject rate doesn't seem to have improved. I'm at latitude 51' and setting both my S30 and S50 to a deviation of 0.0/0.1 still give a very high rejection rate, 3 hours at 60s gave me 95 frames, 4.6 hours at 30s gave 203 frames, and at 20s for 4.5 hours 637 saved frames. There are still frames saved with satellite trails that I can manually delete but not all frames are saved because it says "Star Trails detected"

I can't seem to improve reject rate even if I recalibrate the level/compass and polar alignment.

3AC9bx99

Seestar_S50 Yes if you go into Advanced Feature you can switch off Live. If this is off when in stargazing mode the Seestar will continue shooting and save all the frames. I believe you get no frame rejections and can then manually select and stack good frames using Deep Sky stack. I have never used it myself as its little mentioned in forums. Might be worth looking into.

marvindj

If I recall correctly, if you disable Live Update (I think that's the option name), all lights are saved since they are not being stacked (ie no "Enhancement" occurring on your screen).

marvindj

Well versed folks on Cloudy Nights fora have done experiments on the differing exposure times with the S50 (before 60 seconds was an option). Their data concluded 20s was the optimal setting.

3AC9bx99

marvindj Seems to be the consensus reading around that 20s is the sweetspot with EQ mode. Despite all the hype surrounding the new EQ mode it appears we have only gained an extra 10s exposure time going from AZ to EQ mode. I'm still waiting for my EQ mount to become available but it would be interesting to hear of users experiences with going to 30s and 60s - is image quality improved significantly.

ParadigmShift

3AC9bx99 One thing I've noticed lately, is I get much better results with 30s exposures when shooting in the north. Maybe 70-75% successful frames. Anywhere else in the sky, that number drops to half. So unless I'm galaxy hunting in the North (which is rare for me), I usually will stay with 20s just because it works great.

marvindj

3AC9bx99 EQ mode: An extra 10 seconds plus elimination of field rotation noise. From all I've read, expecting a device of this price point to be able to do better is a bit of a stretch....