[APML] MF cameras, films and Tak scopes

[Alan Voetsch <critter12952@yahoo.com>]

This was just sent back to me. Been getting lots of "delivery failures"
lately.

Alan

> Hey Don,
> 
> --- westergren <westergren@netzero.net> wrote:
> > The 120 film size is a very old design, with a paper backing and
> > enough film
> > for 12 2-1/4 inch square pictures.  The 220 film size uses a paper
> > leader at
> > each end of the film and uses a longer film so you get twice as
> many
> > pictures per roll.  The paper is necessary to keep the film light
> > tight before and after exposure.
> 
> Which brings up the question: why does 120 need paper for
> light-tightness and 220 does not? If it's necessary for one, seems
> like
> it would be necessary bor both. Obviously not, so I must have missed
> something basic.
> 
> Is it the job of the camera back to determine how how long the film
> length is?
>  
> >  For astro use, only the 220 size can be
> > used
> > easily with a vacuum back to hold the film flat, since applying
> > vacuum to the paper backing on 120 size would do no good.
> 
> I assume from this that very little (if any) 120 film is used by
> folks
> like us?
> 
> > I haven't tested 120 vs 220
> > film to see if there's a difference, but I have compared 35mm with
> > 120 size
> > of E200 and Provia 400, there is no detectable difference in light
> > sensitivity out to 4-1/2 hours between the two sizes.
> 
> Thanks, you are the master. :-)
> 
> > I don't have experience with the FS128, but I own and regularly use
> > my FSQ
> > for 35mm AP.  It is an amazing scope, with sharp pictures, and
> > fantastic
> > visual views with eyepieces from 3mm to 55mm.  The FSQ does have a
> > "hot spot
> > in the middle" which shows up in some of my 35mm shots.
> 
> I'm aware of the hot spot and think I can live with it. In a related
> question, are there any comparable scopes that I should consider that
> are under $5K, and still fall into the realm of 'portable'. This is
> one
> of the major selling points of the 106 for me.
> 
> Also, does the FS-128 have an advantage as far as the hot spot? Oh
> yeah, sorry, you haven't used one. Anyone? I'd guess it would be far
> less of an issue because of the f/8 tube. But does using the Tak
> reducer bring this up as an issue?
> 
> > You can not see any of the vignetting
> > effect in visual work with the scope.
> 
> I've heard that too, but I seldom use my scopes visually anyway. My
> wife is starting an 18" truss design so that will cover the visual
> aspect.
> 
> 
> Thanks,
> Alan
> 
> 
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