Minimum exit pupil????

What is the minimum recommended exit pupil? I've read a bunch and have seen cited .5mm. Is that it? Thanks!!!!!!
Mike

This is one of those "all depends" questions. I generally use about .8-1mm exit pupil max on my 16" Starmaster, though on great nights I have used .5mm which yields about 800X. However, with my 5" Tak refractor, I can use .5mm and even smaller exit pupils on the moon and planets with regularity. A lot of it has to do with the size and type of scope you are using as well as the local seeing conditions. I would certainly want the ability to get down to at least a .5mm exit pupil with my scopes, but don't expect to use it often unless your optics are excellent and your seeing is superb.

Also, minimum recommended is the minimum you can go and still improve the view in regards to details, etc.

Randy

Michael Koons said:What is the minimum recommended exit pupil? I've read a bunch and have seen cited .5mm. Is that it? Thanks!!!!!!Mike

That's 51x per inch. One of my old books says no more resolution past 60x per inch, or about 0.4mm exit pupil. My own experience in observing says that past 60x per inch there is no additional visible detail.

I am sure that you have heard of scopes where the image does not break down at 100x per inch, but I've never heard it addtionally reported that more fine detail was visible at those magnifications.