09-24-2012, 08:16 AM
Thanks for the explanation. I 'made' the sensors in Photoshop and overlayed two circles and it became clear what you meant.
Best wishes,
Reinier
[quote name='Brightcolours' timestamp='1348472019' post='20355']
As Frank points out, the width of the 135 format is what lenses are being designed around (and most lens mounts too). The corners of the 36x24 frames touch (more or less) the image circle. If you just add more height to that image frame, corners will fall outside the image circle. If we take 43mm to be the width of the image circle, we can determine that a square sensor can have the max. dimensions of 30x30mm.
With MF things are a bit different. Originally, MF was used mostly as a wide image format. Some cameras cropped that wideness for two reasons: compact width of the camera and more photos per film.
MF cameras like my Agfa Record II shoot 9x6cm still, so a 3:2 format like 135format. Then there are 7x6, 6x6, 4.5x6 formats that all crop the 9x6 format. So, if you were to follow that idea, one would just start cropping the 24x36mm image frames to get to more and more square images.
There are even some cameras that adjust the width of MF. The more narrow MF crops can make do with lenses with smaller image circles. The wider panorama MF cameras need lenses with wider image circles.
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Best wishes,
Reinier
[quote name='Brightcolours' timestamp='1348472019' post='20355']
As Frank points out, the width of the 135 format is what lenses are being designed around (and most lens mounts too). The corners of the 36x24 frames touch (more or less) the image circle. If you just add more height to that image frame, corners will fall outside the image circle. If we take 43mm to be the width of the image circle, we can determine that a square sensor can have the max. dimensions of 30x30mm.
With MF things are a bit different. Originally, MF was used mostly as a wide image format. Some cameras cropped that wideness for two reasons: compact width of the camera and more photos per film.
MF cameras like my Agfa Record II shoot 9x6cm still, so a 3:2 format like 135format. Then there are 7x6, 6x6, 4.5x6 formats that all crop the 9x6 format. So, if you were to follow that idea, one would just start cropping the 24x36mm image frames to get to more and more square images.
There are even some cameras that adjust the width of MF. The more narrow MF crops can make do with lenses with smaller image circles. The wider panorama MF cameras need lenses with wider image circles.
[/quote]