[rollei_list] Re: OT:Walter Voss Diax cameras
- From: CarlosMFreaza <cmfreaza@xxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Thu, 22 Oct 2009 22:41:55 -0300
there is a mix about two different measurement systems, I have
measured true negatives and slides using the same metric decimal
system, the size is 56x56mm, some negs has slight variations from 56mm
to 56.5mm (I think the film paper back has to do with these slight
variations) changing the diagonal from about 79 to 79.4 mm, my 220
negs have 56x56mm exactly. Rollei literature says 56x56mm and 79.2mm
for the diagonal according the Pytagoras theorem. 2 1/4 x 2 1/4 inches
are 57.15mm x 57.15mm and then slightly bigger than the real frame
size on the roll according my measurements.
Carlos
2009/10/22 Richard Knoppow <dickburk@xxxxxxxxxxxxx>:
>
> ----- Original Message ----- From: "Eric Goldstein" <egoldste@xxxxxxxxx>
> To: <rollei_list@xxxxxxxxxxxxx>
> Sent: Thursday, October 22, 2009 5:24 PM
> Subject: [rollei_list] Re: OT:Walter Voss Diax cameras
>
>
> 83 mm is the diagonal for 2-1/4 square.
>
> I also read somewhere in the deep dark past that the f/2.8 lenses for
> the Rollei TLRs were taken from 75 to 80mm because the slightly longer
> lenses would be easier to correct as faster optics. It is reasonable
> to assume that this was the case, as it makes sense from a design POV.
>
>
> Eric Goldstein
>
> Exactly what I said:-)
> I measured a couple of Rollei negatives (also a Rolleicord IV film gate)
> and found they were exactly 2-1/4 x 2-1/4 so the calculated diagonal comes
> out about 81 mm. If you use 6x6 cm it will come out nearly 85 mm but that is
> not the size of the actual negatives.
> There are cases where the "nominal" film size is not the actual film size.
> This is especially the case for sheet film of 4x5 and larger. The film is
> smaller. I think this may be due to the film being intended for use in plate
> holders with adaptor sheaths but that would not explain why smaller sizes
> are the same for nominal and actual. Perhaps its because they came along
> later in the history of film. I think glass plates are actually the nominal
> size but have none to measure.
> The difference is significant, for instance the calculated diagonal of
> 4x5" is 6.4 inches (about 163 mm) while the actual image diagonal is only
> about 152 mm.
>
>
>
> --
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@xxxxxxxxxxxxx
> ---
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