I‘ve been spending the last couple of days in testing mode. Specifically, seeing how my lens collection functions with the Canon 20D. Here are my initial results.
I did a quick and dirty sharpness test on a dozen lenses, using lines of varying width on a sheet of paper and cut up magazine pages, one in the center and one in the corner. I examined them at 100% in Photoshop, using minimal sharpening, with a subjective condition code similar to what I used when I collected coins as a kid—P for poor, G for Good, VG for VG, E for excellent. I was particularly interested to see how lenses made for analog staked up against the lenses designed specifically for digital.
In general, I learned what I expected to learn. No lens is very sharp stopped all the way down, and most don’t perform well wide open. Any lens looks great at f/8. The digital lenses, the 10-22mm and the 17mm-85mm, are better lenses racked wide angle and wide open than anything else I own. Zoom lenses generally perform better at the high end of the zoom, especially the digital lenses, which look good wide open at the center and the edge. The sharpest lens I own is my 85mm f/1.8, which is good to excellent across the entire range.
All lenses exhibit chromatic abberation. The worst offender is, surprisingly, the 17-85mm digital lens at the 17mm setting. It needs a correction of –38 on the R/C adjustment to bring it into line.
All my wide angle zoom lenses exhibit pincushioning at their widest setting. The 17-85mm again was the worst of the lot.
My next testing bout is going to tell me how much exposure latitude I have, really. Stay tuned.
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