Stacked 30 long exposure shots of the Milky Way and got more noise than a single 3-minute frame

I figured stacking shorter subs would smooth out the sensor noise, but somehow the combined result looked grainier than the single longer exposure. Anyone else run into this with DSLR astrophotography, or did I mess up the stacking settings?

2 comments

2 Comments

stella_murray19d ago

Oh man, I totally feel your pain on this one (it's such a letdown when you put all that effort in and it looks worse). I've been there with my old Canon DSLR where I thought stacking 20 short exposures would be the magic trick for clean shots, and nope, it came out all splotchy and weird. The thing is, shorter subs don't always give the stacking software enough signal to work with, so it ends up amplifying the read noise instead of smoothing it out. I messed up my first few tries by not dithering between frames, which lets the software identify and reject the hot pixels and random noise spots. Also, make sure you're using dark frames and bias frames, because without those calibration files the stack just piles up all that camera noise. It's a frustrating learning curve for sure, but once you dial in the settings it really does get better.

oliviat1719d ago

Lol I feel this in my soul! My first attempt at stacking looked like I'd dropped my camera in a bowl of soup and then tried to clean it with a cheese grater. I swear I spent two hours dithering like a maniac between frames and still ended up with more hot pixels than actual stars. And dont even get me started on the dark frames situation - I used a warm dark from like 30 degrees higher and it just made everything worse, like adding salt to a wound that was already bleeding noise. It took me three cloudy nights of re-doing my calibration library to realize my bias frames were literally trash because I forgot to cover the lens cap fully hahaha. Total facepalm moment but hey, you learn by failing right?