Re: Re : ATM Prime focus

[Bratislav Curcic <epabcc@epa.ericsson.se>]

John Maxwell wrote :

> My understanding of "prime focus" is that it's more of a mechanical
> engineering term than an optical one. When speaking about large
> telescopes,

So the question again :
what is a 'mechanical prime focus' of SCT ? What is a 'mechanical prime
focus' of average amateur's Newtonian ? What is 'mechanical prime focus'
of Herrig's convex primary double-pass TCT ?

I'm NOT disputing fact that someone calls the place where you sit in a 
large telesope 'prime focus'. I said that already, it would be silly 
to call these "Wynn focus" or "Gascoine focus" or whatever; besides 
with so many possible configurations one NEEDS distinctions between 
different foci.

What I _am_ disputing is that we're not allowed to call our (non 
changeable configuration) telescopes' _intended_ focal plane a
"prime focus".

As we're getting deeper and deeper into opinions, let's call it quits.
You call prime foci of your telescopes any way you like it, I'll do the 
same.

If weather holds, I may try some TERTIARY focus imaging with my telescope
tonight. That's becasue strong oblate of its main mirror produces horrible
images at PRIME focus. So I may add a corrector, and possibly a diagonal flat, 
because my head will block the incoming light while trying to focus.

Or should I simply call it "imaging at the Newtonian focus of the oblate 
primary, corrected by Shmidt-like-corrector-plate" ?

Bratislav