FS7: FS7 and PL mount - E-mount strong enough?

I have a FS7 with the wooden camera Pl mount adapter. Even before joining this forum I had in mind that some PL primes could be heavy enough, to justify have focus issues.
Well, I first tested a set of Mini Cooke primes and noticed a curious issue : the primes were impecable on the Croziel lens projector and also on the Richter collimator, but, checking on the camera ( FS7 ), I noticed big focus issues on the short focal lenses, 18, 25 and 35mm. With the 50, 75, 100 and 135mm, the focus on camera was great, matching all the focus scale marks !
Had anyone an issue like this ?
 
Unfortunately , the FS7 does not have a way to adjust the back focus, so it could be a fundamental camera problem.
 
Fixoptics said:
I have a FS7 with the wooden camera Pl mount adapter. Even before joining this forum I had in mind that some PL primes could be heavy enough, to justify have focus issues.
Well, I first tested a set of Mini Cooke primes and noticed a curious issue : the primes were impecable on the Croziel lens projector and also on the Richter collimator, but, checking on the camera ( FS7 ), I noticed big focus issues on the short focal lenses, 18, 25 and 35mm. With the 50, 75, 100 and 135mm, the focus on camera was great, matching all the focus scale marks !
Had anyone an issue like this ?
Click to expand...


That sounds like the same problem I had with my Sony F3, P+S Technik BNCR adapter and a set of Super Baltar primes.

The longer focal lengths were more or less in focus and the wider you went the worse it got. The lenses had just been serviced at Duclos and showed perfectly on their projector.

In the end I took the camera to Ablecine and they determined that the flange focal distance / back focus was out of spec and had to be adjusted. That's pretty easy to adjust on the F3 (there is a dedicated screw on the front of the camera), but since this option is lacking on the FS7 my guess is the mount will have to be shimmed. A reputable service department should be able to deal with this on the FS7.
 
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I doubt you can do it on the FS7's E mount . More likely on the PL adapter. Quite a few of those actually have back focus adjustments built in.
 
how to mesure the pl->e adapter

how to mesure the pl->e adapter

Harry Lime said:
That sounds like the same problem I had with my Sony F3, P+S Technik BNCR adapter and a set of Super Baltar primes.

The longer focal lengths were more or less in focus and the wider you went the worse it got. The lenses had just been serviced at Duclos and showed perfectly on their projector.

In the end I took the camera to Ablecine and they determined that the flange focal distance / back focus was out of spec and had to be adjusted. That's pretty easy to adjust on the F3 (there is a dedicated screw on the front of the camera), but since this option is lacking on the FS7 my guess is the mount will have to be shimmed. A reputable service department should be able to deal with this on the FS7.
Click to expand...
It should be actually pretty easy to find the problem component.
The adapter has to measure 34mm exactly from flange to flange.
If it's more you won't reach infinity
If less you pass infinity on the lens but won't reach the close focus.
Of course it depends on the amount of error.
Same with the BNCR actually-it should be 42.47mm
I would not touch the camera flange just shim the adapter accordingly.
This way every adapter , as long as it is the correct size will be swappable on your camera. That's the idea behind adapters. Apparently it gets twisted all the time...on camera forums ;-)
 
optitek said:
I would not touch the camera flange just shim the adapter accordingly.
This way every adapter , as long as it is the correct size will be swappable on your camera. That's the idea behind adapters. Apparently it gets twisted all the time...on camera forums ;-)
Click to expand...

Totally. Make sure the native mount is correct and then shim the adapter.


:-)
 
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