Re: Splitting 70mm film and different versions of Aerochrom

["Willem-Jan Markerink" <w.j.markerink@xxxxx>]

On 23 Jul 97 at 8:04, BIELECKJ@xxxxxxxxxxxxxxxxxxxx wrote:

> ><pondering mode on>
> >Mmm....could it be that those emulsions are so IR-sensitive that the 
> >focus shift *does* become visible with anything else than 
> >apochromatic optics or small apertures?
> >This market should not have a problem with such high end optics,
> >which might be very good reason why these emulsions will never be
> >available for the consumer market. 
> >Does the data sheet cover the issue of focusing differently than for 
> >2443?
> 
> I saw some pictures of a 9.5" aerial camera a few weeks back at an aerial 
> photo seminar put on by the remote sensing specialists at Michigan State 
> University.  While I can't comment on the optics, all of the cameras had 
> very elaborate vacuum film backs which insured that the film would be held 
> tightly against the pressure plate.  Rollei's 70mm back uses the same basic 
> type of design.   

Right, because the Mamiya 70mm back has a vacuum system build in, and 
the Rollei back uses Mamiya internals....:-))
I now have two Mamiya backs, but none came with the (optional) vacuum 
bulb....:-((
Though it seems as if it is only necessary after storing the back
with film still in it. Thin aerial film is more vulnerable, and curl
from the roller is then right in the middle of the image area, and
can cause a focus error. 
Jim Henderson said you must waste 2 shots before shooting the rest 
of the film.

PS for those working in the aerial business: if you ever have
surplus/expired 70mm/9.5" film available, whatever emulsion, I would
be more than interested in obtaining a few spools....;-))
Any known (Net) addresses for this stuff perhaps?


- -- 
Bye,

Willem-Jan Markerink


      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]
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