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disemjg
Joined: 10 Jan 2002 Posts: 474 Location: Washington, DC
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Posted: Sun Jun 01, 2008 3:17 pm Post subject: Goerz Dagor 3 1/2" f6.8 |
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Can anyone tell me something about this lens? The FL works out to be about 87mm, so my guess is that it would be a normal for a 6X6 or maybe 6X7 unless I am mistaken.
Were there wide angle Dagors, and if so how were they identified?
Thanks
John |
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pv17vv
Joined: 22 Dec 2001 Posts: 255 Location: The Ardennes, Belgium
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Dan Fromm
Joined: 14 May 2001 Posts: 2122 Location: New Jersey
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Posted: Mon Jun 02, 2008 9:59 am Post subject: |
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John, not to quarrel with Georges' reference, but my friend Eric Beltrando has calculated performance for Dagors and Boyer's dagor type the Beryl. See www.dioptrique.info .
Eric tells me that although manufacturers, e.g., Boyer, claim that the lenses will cover 85 degrees at f/22, in fact 70 degrees is more nearly correct and that for stringent applications, e.g., repro cameras, 50 degrees is all that one should expect. There have been acrimonious discussions of the LF forum about Dagors' coverage; go there and search for lousy Dagor if you want a good laugh.
IMO coverage is in the eye of the beholder and you'll have to ask the lens what it can do. If I had your lens I'd use it on 2x3, possibly 3x4, not 4x5. |
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Les
Joined: 09 May 2001 Posts: 2682 Location: Detroit, MI
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Posted: Mon Jun 02, 2008 7:19 pm Post subject: |
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Wide angle Dagors are usually marked as such and are usually f9.5. _________________ "In order to invent, you need a good imagination and a lot of junk" Thomas Edison |
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