RE: [APML] Medium format cameras and films, along with Tak scopes

["Gene Horr" <genehorr@houston.rr.com>]

From: astro-photo-bounces@seds.org
[mailto:astro-photo-bounces@seds.org]On Behalf Of Alan Voetsch

> Given that I currently have a Tak FS-102, anything larger
> than a 645 size will be useless for prime focus with a 2.7" focuser.
> Correct?

Well, sort of.  The size over 645 will need to be cropped.  So if
you already have a P67 and an adapter for same I wouldn't run out
and buy a Mamiya.

> Then, I would like to ask the following:

> 1. Film size: is it true that 120 and 220 are the same film except that
> 220 is longer? 

Correct.

> 120 has paper backing, why? Are those the only differences between the 2?

The paper backing is to prevent light from ruining the neg.  For the 220
size the roll becomes too thick, so the paper is removed except at the
ends of the film to allow it to fit on the same size roll.  Otherwise
everything is the same.

> 4. Of the FS-128 & FSQ-106, which is the superior imaging platform for
> prime focus? I don't think all 128s have 4" focusers, but I intend to
> get one that does. I suspect the answer is the 106, but does the extra
> aperture of the 128 carry weight here?

Well, for film the faster speed of the 106 helps a lot.  Plus it is
a smaller length which gives you more stability.  I would pick the 106,
but you won't go wrong with the 128 either.

> 5. Given a 4" focuser, is the Pentax 67 a good choice?

Yes, although if you don't mind making a custom adapter a 'blad 6x6 
might have less vignetting.

> Anyway, I now believe that all the sizes that are measured in
> centimeters are medium format sizes. 4X5 inches is large format,
> correct?  

Correct.

> I can't believe how puny 35mm looks on the same page with the larger
> sizes. 

<g>.

Gene Horr
genehorr@houston.rr.com


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