Blurry Canon EF85mm f/1.8
The photographer who assumes a prime (non-zoom) lens is unlikely to suffer from optical alignment issues is in for some disappointments. It’s difficult to say whether this is quality control, or whether lenses are put out of kilter during shipping. Some of both is possible. But the end result of blurry images is the same for the photographer who puts a lens into service without verifying its performance first.
I purchased an Canon EF 85mm f/1.8 in February, 2007 (in part to take advantage of a rebate with the Canon 5D), but had not used it other than to verify basic function until June, when I gave it my standard “sanity check” prior to putting it into service.
I particularly like shooting fast lenses wide open and sometimes off-center, so edge performance is of particular interest to me (and at any rate, a lens should perform to specification!). As seen earlier in this article with the Canon EF 70-200 f/4L IS, stopping down isn’t a solution, and my intended uses for the 85mm f/1.8 rarely include stopping down beyond f/4; I would typically shoot it at f/2 or f/2.8.
A number of test frames at f/1.8 were taken on the Canon EOS 1D Mark III with the same results: blurred on the left, quite sharp and contrasty on the right.
Some frames were acceptable, being only subtly “off”; this is because a zone of sharpness does have some depth, and the plane of focus does achieve a happy medium in some cases. But when focus is spot-on, a loss of detail and contrast on one side of the image is starkly clear. See for yourself below.
Too much time has elapsed to return the lens, so off to Canon Service it goes (June 20, 2007). We shall see how Canon fares at correcting the problem. Update: the lens came back performing well (sorry no followup pictures).