Roger Cicala of LensRentals.com has completed the second part of his two part series investigating lens testing.
In the first part: “There is No Perfect Lens“, Roger explored about the sharpness variability that is inherent to consumer-grade lenses:
“My first thought when seeing more variation than expected was our testing methods weren’t accurate. So we refined testing methods, eliminated bad copies, and tested only new copies. The variation was still there.
“Like most people testing lenses, we used Imatest. But maybe a lens-test projector would be better. Nope. Well, the gold standard was MTF measured on an optical bench. So we (despite the vigorous protestations of those-who-manage-the-money) bought an optical bench. It showed a similar amount of copy-to-copy variation.”
In the second part: “There is No Perfect Lens Test, Either”, Roger compares testing using Imatest to the expensive optical bench. He makes some valid constructive criticisms about how a variation in SFRplus region selection can lead to different reviewers having a variation in their test results. Roger also writes about how chart quality can be the limiting factor for measurements, and the importance of testing multiple focus distances. (more…)