Canon 5D Mark II and optics

See also Jan 7 entry. I did some field shooting today with the Canon 5D Mark II using the 24-105mm f/4L, the 70-200mm f/4L and the 50mm f/1.2L. Not my usual optical fare, but I thought it worthwhile to see how some regular Canon lenses would do.

My impression is “we need better lenses!”. The lenses I mentioned can produce very good results, but depth of field and edge/corner sharpness just aren’t very appealing, even at f/8. Combined with obvious field curvature in some cases, it makes it tough to create a sharp image of some subjects. That’s the world we now enter with ultra high resolution cameras trending beyond 21 megapixels towards 30-40 megapixels.

Even with prime lenses it’s an issue: I have yet to find a 50mm lens of any brand (Canon, Nikon, Zeiss, Sigma, Olympus) that delivers sharpness across the frame without weird field curvature of some kind, far from an academic issue.

I had been field shooting the 5DM2 with the Zeiss ZE 50mm f/1.4 Planar, and finding that I was not getting sharp images across the frame, even at f/5.6. This led me to some controlled tests. Serendipity resulted in finding a scene that shows just how bizarre the field curvature is on a variety of 50mm lenses (not the scene below). How about sharp edges 100 feet in front of the center? I’ll be writing the field curvature issue up in detail in DAP. Here’s one example I came across today; observe the sharp leaves at upper left, a good distance in front of the center, where the point of focus lies.

Field curvature — leaves in corner are about 100' (33m) in front of the center
Canon 5D Mark II EF 50mm f/1.2L @ f/1.4

Of course, one way around all this frustrating sharpness stuff is to embrace it, and shoot with minimal depth of field: after all, drawing the viewer’s eye to one sharp spot is all that its really needed.

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Canon EOS 5D Mark II + EF 50mm f/1.2L @ f/1.2