Optimum Exposure Length - Forums

Topic starter

Dec 17, 2021

Hi all.

Whilst randomly browsing images in AstroBin I happened upon this one - https://astrob.in/agsyir/0/.

I thought it might be worth sharing - following the discussion on Monday - as it gives an alternative take on the subject of exposure lengths. Not everybody will like the idea of the number of frames involved though, I'm sure!

All the best

Tim

Well Written

MartinBaker@1848

Moderator

Dec 17, 2021

Well, that lot will slow up the PC. Blooming lovely result and shows it’s total integration time that is needed.
Being sad I had to work the figures out.
Ha 3.3 Hrs
L 2.1 Hrs
RGB 0.5 Hr each
In rough numbers.
1.5 & 2 sec subs. No guiding needed.
Didn’t see where it was taken.

Tim Ellison

Topic starter

Dec 17, 2021

And presumably the short exposures would mean that a quite (very?) rough and ready polar alignment would suffice. Although a decently solid mount and an ability to track the target reasonably well would still be important. Does it offer you anything to chew on Keith??

maxchess

Dec 17, 2021

This guy was using a "Nauris Mirrage 600 mm f 3,8 Dobson" this scope is not capable of accurate tracking so he was forced to use very short exposures to avoid star elongation / trails. Interestingly he used a Pegasus rotator to avoid field rotation. The total integration time for this image was 8 hours and the quality is relatively poor for this amount of time. There are clear photoshop halos round the main image.
See this image

with the same camera using only 3 hours and in Bortle 8 skies.

Max

Helpful Insightful