I didn't know which part of the forum this belongs to, but since it's gear specific, I decided to put it here.
I noticed that my Minolta 58 1.2 cuts bokeh circles at the bottom of the frame. It only happens wide open at the bottom of the frame. It goes away around f1.4-f2
This is in portrait position, and the physical bottom of the frame is on the left side. I googled around and found only one post on flickr about this. The poster stated that the only wide aperture lenses (s)he knew not to suffer from this are Leica (on Leica bodies). This was taken with Canon 7D.
Is this expected? My 50 1.8 doesn't do that, but neither does the Minolta at 1.8.
Thanks.
Stop down to f/22 or something like that. Press the DOF preview button. The shape the blades make (point the lens at yourself while the DOF preview is on) is going to be the same shape as OOF highlights. Maybe one of the blades is caught, so it isn't closing to complete the circle. Just a guess.
Put this over on the Alt Gear Forum - a.k.a. - the Rokkor Channel. You'll get a lot of responses - they're busy with Zeiss right now and could use a good new Rokkor thread.
I know this has been discussed before - you could try a search.
mt-m - you may be correct, however, I get the truncated cat's eye on a full frame.
mMontag wrote:
mt-m - you may be correct, however, I get the truncated cat's eye on a full frame.
"cat's eye" effect is internal vignetting of the lens elements. Vertical or horizontal cutoff is definitely the result of the mirror box. It happens on full-frame cameras too.
Looks like it must be the close proximity of the flipped-up mirror to the top of the sensor (the image is flipped, in-camera) that's the culprit. There's much more clearance near the bottom edge of the sensor because of the well the AF sensor assembly sits in.
Stop down to f/22 or something like that. Press the DOF preview button. The shape the blades make (point the lens at yourself while the DOF preview is on) is going to be the same shape as OOF highlights. Maybe one of the blades is caught, so it isn't closing to complete the circle. Just a guess.
How could this be? as it would show in all the circles and the OP states it only happens wide open not stopped down even a stop
Stop down to f/22 or something like that. Press the DOF preview button. The shape the blades make (point the lens at yourself while the DOF preview is on) is going to be the same shape as OOF highlights. Maybe one of the blades is caught, so it isn't closing to complete the circle. Just a guess.
Ian.Dobinson wrote:
How could this be? as it would show in all the circles and the OP states it only happens wide open not stopped down even a stop
Yes, I changed my mind about that, as I noted in a couple posts up.
