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Waynemel
Tinkerer
Username: Waynemel
Post Number: 63
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, May 15, 2011 - 10:01 am: | 
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I have aquired the Teleskop lens attachment for my Contaflex I. Do I need to compensate for the effective aperture when using this lens?
I would assume I loose some speed. |
Canleikon
Tinkerer
Username: Canleikon
Post Number: 2
Registered: 03-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, May 15, 2011 - 01:43 pm: |
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I believe any optical device which is placed in front of the lens group (other than filters ie. polarizers, color correction, warming, cooling) does not affect exposure. |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 65
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, May 15, 2011 - 08:31 pm: |
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I wasn't sure, but I have read the manual for another camera (Kowa H) and they say that their auxilary lenses reduce the aperture to f4 (from f2.8).
I haven't been able to find any literature on the Teleskop. |
Glenn
Tinkerer
Username: Glenn
Post Number: 923
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 16, 2011 - 04:14 am: |
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The Telescop auxiliary lens is a 1.7x magnification device. When I have been cobbling together high mag combinations for one off projects, I have always worked on the assumption of reducing the max aperture of the prime lens by the magnification factor. Whether my assumption has any scientific basis or not, I always got good results using this ball park figure. |
Br1078lum
Tinkerer
Username: Br1078lum
Post Number: 84
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 16, 2011 - 02:01 pm: |
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The Yashica MG-1 had a set of auxillary lenses made especially for that model, and they won't mount on the G-GSN series. Since Yashica moved the meter to the lens front, any filter mounted would be automatically compensated for without having to change the ASA setting. With the aux lenses on the MG-1, Yashica put a cut-out in the lens mount so that light could still get to the meter. I don't have a manual for the original G series aux lens set, but I do remember reading about compensating for their use. I never used the lenses, so I didn't bother to remember what it was. Glenn's formula sounds about right.
PF |
