Hello.
Does anyone know this lens in f4.7 version? I have bought it recently (still dont have it in hands)but all I can find in the net is about f3.75 version. Nothing about f4.7. Any info about history, focal length etc would be welcome.
Hello.
Does anyone know this lens in f4.7 version? I have bought it recently (still dont have it in hands)but all I can find in the net is about f3.75 version. Nothing about f4.7. Any info about history, focal length etc would be welcome.
Post #27 here.
https://www.largeformatphotography.i...nd-dates/page3
Let’s do some simple maths!
The catalogue version of the 5 bid has a lens diameter of 81mm. The given focal length is 35cm. Using the similar data for the #5 ( lens diameter also 81mm and focal length of 28cm and has a speed of F.3.75.
If we divide 28 by 3.75 we can get very close approximation of the actual effective pupil diameter ( better than 81mm, anyway!). So the real optical aperture is 75mm!
We can can use this for the 5 bis. 35cm decided by 7.5cm gives an F value of 4.6!
The table that I (Steven, not Mark) referred to, mentions which #s are faster but doesn’t mention the slow #5 bis which is obviously a late addition to the range .
So I think your lens is the standard #5bis, with the focal length of 35cm - not 40.
Thanks and sorry Steven.
The optics (front achromatic) is marked rp/40c. It may suggest it was made or repolished for 40cm. I did not noticed big differences between images projected on gg with and without the extension.
I'm just curious , because there is no info anywhere. The barrel is clearly marked f4.7. And the barrel is made of aluminium.
Last edited by Andrzej; 27-May-2023 at 09:25.
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