Optical misalignment with the Canon EOS 24-70/f2.8L
I previously discussed alignment issues with my Nikon D2X, which ultimately required a $400 repair to replace the lens mount on the camera body itself (and taking an outrageous 3 months to perform—the reason my D200 vs D2X review was delayed) .
The Canon EF 24-70/f2.8L apparently is not in my good graces either. My first copy, about 18 months ago, required 2 trips to Canon service to resolve decentering and other optical issues. That copy ultimately proved to be a very fine performer, once the optics were aligned properly. I sold that lens about a year ago.
About a year later, I took up the Canon EOS 1Ds Mark II again, and purchased a new 24-70/f2.8L (about last December). I used it a bit, but hadn't used it for serious shooting to date. However, recently I began to employ it for infrared shooting on my Canon EOS 5D, which I had converted to pure infrared use by MaxMax.com (quick turnaround, clean results).
I immediately noticed softness in infrared with the 24-70/f2.8L, which quickly led me to shoot some tests shots on an unmodified Canon EOS 1Ds Mark II in color, confirming the misalignment with normal color photos (to rule out any infrared weirdness). Click to see the left/center/right color crops, at 50% actual pixels; The left side of the frame is quite blurry.
Even at f5.6 at a distance of about 100 feet there is fairly severe sharpness degradation, with a blurry center and sharper edges, the left edge being the sharpest. Shown below are actual-pixels crops taken from the full frame.
| Optically-misaligned Canon EF 24-70/f2.8L USM, 1/250 sec, f5.6 | ||
| Left | Center | Right |
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Given that the 24-70/f2.8L saw little use, and absolutely never had any rough handling, it’s yet another case of the poor quality control which I’ve discussed before in some of my reviews. The lens is now on its way to Canon service. Isn’t it odd that it’s happened with both copies of the 24-70 that I’ve owned? My 24-105/f4L has no such issues.
