Sorry for ghosting, i got busy for a while. The reason i was thinking 24 or 27 mm is that i was looking into decent exit pupil so m13 would be as bright as i can get amd still be reletively well framed. Im open to any size though.
So, stars actually don't lose brightness when the exit pupil gets smaller, but spread out objects do. This means that the individual stars in M13 actually contrast *better* against the surroundings when zoomed in because the sky darkens while the stars stay the same brightness (up to a point where things get less crisp - but that point is somewhere between a 1.5mm and 0.5mm exit pupil depending on personal preference and optics quality).
I love my 8mm Delos in my 10" f/5 dob. Stands to reason I'd love a 10mm Delos (I'd probably enjoy the 8mm too) in the 8" f/6 dob. I like my views with a slightly larger exit pupil and therefore slightly more pinpoint stars (hence the 10mm suggestion), but I know a lot of people prefer the extra contrast and scale of zooming in a bit more (hence also seconding the 8mm).
If you do end up getting a wide field eyepiece for wide field objects like open clusters, M81/82 as a pair, etc and don't want to wait for the 24mm Delos, may I also recommend adding the 30UFF to your considerations. It's available under different names a variety of vendors (Celestron Ultima Edge and Stellarvue's version are sold in the US). It's a truly wonderful eyepiece.
Enjoy the scope!
P.S. Do you use glasses when observing or have family who does? It matters a lot for eyepiece recommendations.
Edited by GolgafrinchanB, 02 May 2025 - 05:01 AM.
