M31 the Andromeda Nebula - 11.5 hours - Explore Scientific ED80 apo
click image for larger (50%)

 

The wide dynamic range of this subject is a challenge. This image is a composite of 60 one-ninute, 60 five-minute, and 33 ten-minute subexposures
over two nights of near perfect seeing. One can see a lot of remaining noise streaking in the full size image which means some longer subs or more ten-minute
subs are needed. Longer subs will give more stars in the blank areas too, hopefully...

captured and stacked using Nebulosity 2.1.8, with warm pixel conversion, base color balance, flat frame, and color range with minimum curves in Nebulosity.
Careful final curves and final color balance with soft-light saturation adjustment in Photoshop CS3

Explore Scientific ED80 apo with Astro-Tech AT2FF field flattener at f/6 riding on my Meade Classic LX200 12 inch, Hap mod 350d,
guided by PHD, DSI Pro on the 12 inch at f/3.3 --- sky good but moist, about 2 arc second

enjoy