After a looong dry spell, I posted test results for five more lenses over on our SLRgear.com site. Lenses tested include a couple of long-zoom "vacation" lenses, a couple of dedicated macro lenses, and a very nice ultra-wide zoom from Tokina. Here's the list:
As noted, we're going to be re-testing the Nikon 18-200mm: It does indeed produce soft corners on its images at medium focal lengths, but not quite to the extent reflected in the current set of graphs.
We found after I'd posted the test results Saturday that this lens is extremely susceptible to the effects of very minor mis-focusing. Our D2x body has seemed to be focusing OK with other lenses, but apparently back-focuses slightly with this particular lens. The lens definitely produces soft corners at medium focal lengths, but quite to the degree shown in the current graphs. We're hoping to get new results posted tomorrow before an upcoming business trip of mine, else it'll be next Saturday before I can manage it.
This underscores the painstaking nature of lens testing: In today's reshoot of the Nikon 18-200mm, Luke shot no fewer than 450 individual exposures, which will now take the studio computer all night to process through DxO. Despite the pain and effort involved, we're looking at applying this focus-bracketing protocol to all lenses we test going forward: We're committed to bringing our readers the most accurate and reliable lens performance data available anywhere.
And stay tuned: We hope to get another few tests posted before the PMA crunch, including those of the (excellent) Canon 24-105mm IS, Tamron 17-35mm, Tamron 24-135mm, and full-frame results from the very nice Canon 28-135mm IS.