Stephen Paul wrote:
Hi Stephen, thanks for your response. I don't understand. You mention
0.8mm as if it has almost the authority of a speed limit. Is there a
reason why 0.8mm would be the point where you go from seeing more detail
to just making things bigger? Does it have to do with 0.8mm making the
Airy disc visible to the eye?

I'm not ignoring this post by the way. I just don't have an answer that I
like.

At an exit pupil of 0.8 mm, the Airy disc has an apparent (that is,
magnified) size of about 2.3 arcminutes (for light at 550 nm). Where
that figure comes from is out of the scope of this post, but that is
around the point where the disc becomes more obviously a disc and not
a point of light.

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt