[rollei_list] Re: 120 Film flatness, Rollei TLR plane glass, etc ..

2011/8/19 Emmanuel Bigler <Emmanuel.Bigler@xxxxxxxx>:
> ....My understanding is that the Zeiss study related film flatness for
> the Contax 645 was triggered by the use of f/2 lenses for which the
> depth of focus at f/2 is 4 times more critical than for a TLR stopped
> down to f/8.....

I found a file with the Modern Photography magazine opinion (Herbert
Keppler) and test conclusions about the Tele Rolleiflex with the
Rollei plane glass, I think this is a summary because I recall the
article with the test had several photographs and numbers; as Richard
K wrote, HK uses mealy-mouthed writing to say this accesory is useless
as final conclusion:

"Tele-Rolleiflex: The New Long Look

"An interesting innovation in the Tele-Rolleiflex is a removable glass
plate within the camera, in front of the film. With such a long focal
length lens, it's understandable that the maker of the camera should want
to keep the film plane as precise as possible."
"You've got to inspect the glass each time you load. Beware of
thumb-prints, grease or dirt that sticks. These will cause greater harm to
the negative than if they were on the lens itself! However, we shot most of
our pictures with the glass in place and each picture we took came out
scot-free."
" We then took the Tele-Rolleiflex out on actual field tests. Besides
checking the lens, we were also interested in discovering how well the
glass plate kept the film flat - in terms of actual picture sharpness."
"With the glass in place, overall sharpness at f/4 was very good with only
the slightest fall-off in definition at the corners and a tiny amount of
flare. Maximum sharpness was achieved at f/8 - and this was sharp indeed.
This sharpness held right down to f/22."
"Curiously enough, when we removed the glass plate, the loss of sharpness
was almost too minute to notice. - H.K."

Carlos
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