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Puderse
Tinkerer
Username: Puderse
Post Number: 1
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 22, 2006 - 11:16 am: | 
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Recently CLA'd an Agfa Record III. Took a roll of pix and found close focus to be a miss. The question is this: when adjusting rangefinder for minimum focus, is the object focused upon measured at a distance from the lens or the film plain? The further the object is from camera the less relevant this is. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 71
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, September 23, 2006 - 06:59 pm: |
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Place a groundglass in the film plane and adjust the rangefinder to give sharp focus on the groundglass. Never go by measurements from the engraved distance numbers on the lens mount. |
Puderse
Tinkerer
Username: Puderse
Post Number: 2
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 25, 2006 - 08:05 am: |
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Precisely! You however have missed the point, or perhaps I have not expressed the point fully. Perhaps you are not fimiliar with this camera, the rangefinder is not coupled. Having placed ground glass at the film plane, and set the camera at minimum focus, do I place the camera 3.5 ft from the FILM PLANE or from the LENS to the target. These three elements; rangefinder, focus mark on lens, and ground glass focus, should be concurrent. If they are adjusted and calibrated at the wrong distance, one introduces more than 105mm of error into the whole operation and the other focus points out to infinity will never be as good as they can get.
To state it another way; the rangefinder is set at 3.5 ft, the focus mark is placed at 3.5 ft. and the target is placed at 3.5 ft. from the FILM PLANE or 3.5 ft from the LENS? The adjustment of the rangefinder is a piece of cake and I can make it read whatever I decide. The focus of the lens can be adjusted by loosening the tiny screws and repositioning the outside focusing element. The shims are for adjusting the infinity focus and they affect focus at all other focus distances. The rangefinder is back on the camera body but not at film plane.
The question remains the same "is the minimum focus distance LENS to subject or FILM PLANE to subject". The difference is about 10% .
Perhaps I am missing the point of using 100 year old technology after using state of the art SLR's for so long. I have already very carefully set the infinity concurrent with ground glass, infinity stop on the lens, and rangefinder. Perhaps I need to establish the error at minimum and try to remember. |
Dan_mitchell
Tinkerer
Username: Dan_mitchell
Post Number: 4
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 25, 2006 - 09:05 am: |
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Distance is from the film plane. |
Jan
Tinkerer
Username: Jan
Post Number: 15
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 25, 2006 - 12:07 pm: |
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Yes, the distance is always measured from the film plane. However, the rangefinder on the Agfa Record III has such a short base that even when adjusted will not be particularly accurate.
I did own a Record III and it was the rangefinder that made me sell it and use a Zeiss Super Ikonta instead.
The Record III has an accessory shoe - try finding an old Leica rangefinder or something similar that could be mounted in the shoe; anything will be more accurate than the built-in uncoupled one.
All the best,
Jan |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 72
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 25, 2006 - 09:30 pm: |
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sorry about that. you're right, i am not familiar with the Record III and did not know it had an uncoupled rangefinder.
At the distances these work at and the speed of lenses they have, the distance from the lens to the focal plane is not very significant. The correct place to measure is the film plane, but it may not really matter in practice. |
