07-28-2013, 08:27 AM
For macro use, I never understood the often repeated claims that extension tubes don't degrade image quality like a front mounted "close up filter" does, since you are pushing the lens outside its design intent. Anyway, when using the 50mm f/1.8 II I had noticed you get massive field curvature when you use extension tubes. I didn't pay attention to what other nasties it may or may not have added too, but wouldn't be surprised if there's more.
<a class="bbc_url" href="http://snowporing.deviantart.com/">dA</a> Canon 7D2, 7D, 5D2, 600D, 450D, 300D IR modified, 1D, EF-S 10-18, 15-85, EF 35/2, 85/1.8, 135/2, 70-300L, 100-400L, MP-E65, Zeiss 2/50, Sigma 150 macro, 120-300/2.8, Samyang 8mm fisheye, Olympus E-P1, Panasonic 20/1.7, Sony HX9V, Fuji X100.