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Deadly
Tinkerer
Username: Deadly
Post Number: 2
Registered: 02-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 26, 2007 - 11:31 am: | 
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I have just purchased a Contaflex II. I am mystified by the markings on the exposure setting knob. It offers aperture and shutter speed settings, for either ASA or DIN film speed ratings, all on the same knob. However, the ASA speeds do not seem to match those for DIN. If I set the DIN index to 27, then the ASA rating shows somewhere in the region of 180 to 200.
This results in different aperture and shutter speed readings, for the same film, dependent upon whether one uses the DIN or the ASA index. It seems that this was deliberate, rather than the result of damage or wear, since these indices shown on each half of the same component.
Does anyone have any ideas about why this would be so, please? |
Alex
Tinkerer
Username: Alex
Post Number: 17
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 27, 2007 - 09:55 am: |
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DIN and ASA scales were realigned in the early sixties. Before then, a DIN rating of 21 was approximately equivalent to an ASA of about 50, although they were actually measuring different things. An increase of 3 degrees in DIN represents a doubling, so 27 DIN would have been in the region of 200. ASA values incorporated a considerable 'safety factor' in minimum exposure values, by a factor of as much as x4, so when the scales were realigned, DIN 27 became approximately equivalent to ASA 400. My old Ikophot light meter, for example, shows the older scale equivalences, and so has to be adjusted for modern emulsions. The Contaflex II came out in 1954, so I guess this is why your DIN and ASA matchings are showing as they do.
Alex |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 193
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 27, 2007 - 09:51 pm: |
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Gee, I never knew that..... |
Alex
Tinkerer
Username: Alex
Post Number: 19
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 28, 2007 - 04:58 am: |
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Rick, I cannot believe there is a single thing about photography you don't know that's worth knowing! |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 194
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 28, 2007 - 05:08 am: |
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well.....
i guess it must not be worth knowing then!
: ) = |
Deadly
Tinkerer
Username: Deadly
Post Number: 3
Registered: 02-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 01, 2007 - 01:37 am: |
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Thanks very much Alex! I've been puzzling over this one for some time. In the end though, I've loaded the thing up, and started to take pictures; an ASA 400 film, with the camera set using the ASA scale.
Information much appreciated! Hopefully, now I can get some reasonably exposed shots from this little beauty.... |
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