[rollei_list] Re: Rollei 35 mm SLR Flange focal distance
- From: CarlosMFreaza <cmfreaza@xxxxxxxxx>
- To: "rollei_list@xxxxxxxxxxxxx" <rollei_list@xxxxxxxxxxxxx>
- Date: Tue, 9 Sep 2014 14:31:26 -0300
2014-09-09 13:32 GMT-03:00 Bigler Emmanuel <bigler@xxxxxxxx>:
> Hello All
>
> I think that I have in hands the proper data allowing to solve the Mystery
> of the Rollei 35 mm SLR Flange Focal Distance, thanks to Gérard Métrot, our
> French Rollei expert and repair technician who just sent me the Official
> Rollei Factory Specs as of 1972.
>
> flange focal distance = distance between the lens bayonet seat and the focal
> point = 44,67 mm (an official Braunswcheiger spec _should_ have a comma as
> a decimal separator ;-) )
>
> back focal distance = distance between the last lens vertex and the focal
> point = 44,50 mm
>
> Hence we get the clue for the "variable" figures quoted on the 'net
>
> 1/ confusion between flange focal distance (mechanical - bayonet seat) and
> back focal distance (optical - lens vertex)
>
> 2/ flange focal distance = 44,67 mm explains why some documents mention
> 44.6 and some other 44.7
>
> 3/ those Rollei figures are not really related to the M42x1 flange focal
> distance = "register" in English, quoted as 45.46 mm (not really close to
> 44.67) in this other document:
> http://www.graphics.cornell.edu/~westin/misc/mounts-by-register.html
>
> I home, Dirk-Roger that you can now have a quiet sleep.
> --
> Emmanuel
Perhaps it would be necessary to clarify if Dirk needs the back focal
distance, 44,50mm to assure a right focus for the QBM lenses with the
adapter for Canon, or if the mechanical distance 44,67mm is enough to
assure it or if both distances are the same for practical purposes.
Carl Zeiss confirmed as flange distance for the QBM 44,50mm as I wrote
yesterday and they give the back lens distance to film in their
technical info, f.e. according the Planar 1.4/50 Contax /Yashica
technical sheet the lens back distance "to film" is 45,50mm (there are
no technical sheets on line for QBM lenses).
Carlos
---
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