Noel Sterrett wrote:
The problem was also noticed but has been corrected on an Epic by adjusting (which is possible on the Epic) the flange distance.
While I think it highly likely it is a lens issue, I would strongly advise BM to be certain before shipping large quantities of cameras.
Cheers.
Well adjusting the flange to a lens is never the right thing to do.
The flange depth of the camera should be a constant. If the individual depth of the camera is out then it should be corrected but you shouldn't use a lens that's "out" to make the corrections against.
I only know the depth of PL mount, but it's meant to be 52mm. Using a depth gauge you can set the FFD of the camera to be 52mm.
http://denz-deniz.com/index.php?page=7& ... product=18Then, using a lens collimator or lens projector you can check that a PL mount lens projects an image that is most in focus at 52mm.
If the lens isn't doing that, then you re-shim the lens and fix it. You don't change the camera. If you change the camera to allow for the lens, then the next lens you get won't be right either.
The camera should be a constant and the lenses should be adjusted to match, because they also have variable focus. They have to first hit infinity. And if the lens is out, even if you use the camera to adjust to it, then the lens probably won't hold ocus through the zoom. The camera is just a mount with no adjustments once it's set.
So, if the camera is OK with other wider focal length lenses, even at a deeper F stop, then it's not indicating to me that it's a problem with the FFD.
In my experience, the F stop doesn't influence the depth of focus of the lens (not DOF) as much as the focal length. You should still see an FFD problem at wider focal length even at F3.5.
In other words, the wider the lens, the more critical depth of focus or FFD will be.
There very well maybe be out of spec BMD cameras out there, but it doesn't add up to me that we'd see it only on one particular wide lens, especially when it's been reported as unreliable on other cameras.
jb