Rear mounted filters for Canon lenses
Several Canon wide-angle lenses have a filter mount on the rear to enable users to fit gelatin filters. Late last year, Aurora Aperture sought Kickstarter funding to produce glass ND filters (3, 6, 12 and 16 stop) along with a easily installed mount.
I took the opportunity to run some tests today and the results look quite good. Optically the filters don't degrade the image beyond what can be expected when adding more glass into the light path. Colour shift is marginal and easily corrected on the first 3 strengths whilst the 16 stop offering has a obvious shift of the greens (although still usable).
Shots and crops for colour assessment and optical quality are here for anybody looking to add ND's to their 81-15, 11-24, 16-35, 17-35, 17-40, 14mm or 15mm fisheye
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