Cameras and Lenses
Different objective size, same brightness?
If all else is the same, does exit pupil determine brightness regardless of objective size? In other words, if same manufacturer using same lenses/prisms makes a 10x42 w/ a 4.2 exit and another w/ 8x36 w/ 4.5 exit (not exactly the same but very close), is it fair to expect exactly the same brightness even though one has smaller objectives?
Lilcrazy is a big fan of the bushnell legend ultras in the 8x36 and it made me wonder if the brightness was the same vs. the larger series. Looks like wt savings is only marginal at 2-3 oz.
I have looked thru the 10x42's and am very surprised at how clear and bright they are, not to mention they are inexpensive.
I posted more a while ago and lost everything using a laptop, so here is some information I have done in the past.
http://www.cloudynights.com/ubbarch...5/o/all/fpart/1
A note with anybody reading this what I posted, for convenience I only used a 2 1/2 power booster to check the resolution of the Nikon 10SE and Fuji 10x50 and really it would need to about 39x + to really check the top resolution. I think there is some talk on the link about this, but with this being 5 pages long, click on show all towards right top. Really all I wanted to show was that the Nikon 10SE and the 10x50 Fuji were close, well at least closer than what your eyes would show. I still stand behind my information.
Thanks Surveyor for reminding me.
If the transmission and the magnification are the same and the exit pupil is larger than the eye's entrance pupil then yes diferent objective sizes will have the same brightness.
Making the exit pupil bigger when it's already bigger than the eye's entrance pupil doesn't get any more light into the eye.
Beware of astronomers (in the dark) as they have large entrance pupils.