I hit 500 stacked exposures on a galaxy and it looked worse than 50

Everyone in this sub says more stacking always gives you cleaner detail, but I actually found the opposite. I spent three nights gathering 500 frames of the Whirlpool Galaxy through my 8-inch SCT, stacked them in DSS, and the result was this blurry overprocessed mess. The noise reduction algorithms just killed all the fine spiral structure. Out of curiosity I stacked just the best 50 frames from one clean night, and honestly the image looked sharper with better color balance. The number 500 really surprised me, I thought I was doing the right thing following the "more is always better" advice. But now I think there is a sweet spot that depends on your sky conditions and camera sensor. Has anyone else hit a frame count where their image quality actually dropped off?

3 comments

3 Comments

jade5171mo agoTop Commenter

Yeah I've been down that exact road and it's frustrating because everyone swears by more frames but nobody warns you about the diminishing returns. The issue is usually your sub exposure length and quality - if your individual frames are noisy or the seeing is bad, piling on more of them just bogs down the stacking algorithm with garbage data. Next time try doing a tight quality sort on your subs and only keep the top 30 or 40 percent, you'll probably end up around 150-200 good frames that actually work together instead of fighting each other.

jana_shah1mo ago

@ray356 Yeah the "more bad data" thing is spot on, but your buddy with the dob is probably just getting cleaner sub exposures to begin with.

ray3561mo ago

The 500 number really jumps out at me because I did basically the same boneheaded thing with M31 last year. I stacked 400 frames from my 130mm scope and ended up with this weird plastic-looking Andromeda that looked like it was made out of Play-Doh (not the good kind either). I swear the noise reduction just ate all the little dust lanes and made everything look like a bad watercolor painting. My buddy who only ever stacks around 80 frames on his 10-inch dob always gets way better results than me, and I've been doing this for like 4 years now. So yeah, I definitely think there's a point where more frames just becomes "more bad data" and your processing software gets confused (or maybe I just have bad luck, who knows).