okay braintrust
when one flips that back section to the front creating a 17" lens.. does the effective aperture change from f5 ?
I imagine it would, yet there are not markings for it on the studio shutter it is in
okay braintrust
when one flips that back section to the front creating a 17" lens.. does the effective aperture change from f5 ?
I imagine it would, yet there are not markings for it on the studio shutter it is in
I'm pretty sure It's about double the combined lens speed, so around f10 Maybe a hair less like a 1/3 of a stop.
thanks
at least that is somewhere to start
Garrett
flickr galleries
FWIW http://www.cameraeccentric.com/html/...lensak_13.html
Vesta is on pp.24
One man's Mede is another man's Persian.
The vesta is f/5 normally no? so that would give you a diameter of 2.3 inches max, so when shot with the cemented doublet keeping the same 2.3 inch max aperture would give you a speed of f/7.39. Might want to check the math on these as I dont have the hardware in front of me, but I think thats right.
Approximately F8, but it may be slower due to the iris fixture. Like Dave says, Wollensak called them F5, so that supposes a 2.2" apparent aperture (11 divided by 2.2 = 5). So if it changes to a 17", it would be 17 divided by 2.2. You can verify this by measuring the opening when you have the lens.
Garrett
flickr galleries
Bookmarks