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 --- Rollei List - Post to rollei_list@xxxxxxxxxxxxx - Subscribe at rollei_list-request@xxxxxxxxxxxxx with 'subscribe' in the subject field OR by logging into www.freelists.org - Unsubscribe at rollei_list-request@xxxxxxxxxxxxx with 'unsubscribe' in the subject field OR by logging into www.freelists.org - Online, searchable archives are available at //www.freelists.org/archives/rollei_list