I have yet to notice a problem with any lenses and I have quite a few older vintage Minolta stuff, including an early product 50mm f1.7, various lenses from the 70-210mm f4, 35-70mm f4, early version of the 28-85mm too. No issues to report with any of those with electronic front curtain shutter, and believe me I'm in the frame of mind where I certainly would notice problems
Tamron wise again nothing noted there 17-35mm no problems, nor the 90mm f2.8. But occasionally for some reason the A57 thinks no lens is attached, I've seen this mentioned in a few threads, it happens infrequently for me. But I've never noted this on the other cameras I've had.
