[MF3D.FORUM:34] Re: Apparent image size, MF verus

[Tloc54452@xxxxxxx]

> If a slide viewer is adjustable, most people will focus to place the
> image at their near point, where it will be largest. 
[...]
> Of course, all this depends on your particular eyesight (YMMV).

I would say "most young people".  I think most old people focus out,
or, if they have no accommodation at all left, use their upper lenses, 
which is the same as focussing out.  It's just more comfortable to
focus out when your eyes strain to focus in.

Since Richard is quite obviously on the ball, I'd like to ask him a 
question.  Here's one I don't have enough geometry to crack.  How 
many steradians do these different formats subtend?  I think that 
might be the best way to characterize format coverage but I have had
no luck finding what a rectangular format subtends.  It would be 
easy if the formats were circular but then there would be no need to 
find solid angles - they'd be implicit.  80 and 44 mm are fine with
me for examples.

Thanks,
John B