Micro Four Thirds Focal Reducer Shootout

Started 5 months ago | Discussions thread
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Given your clear vested interest in the results......
In reply to brian, 5 months ago

How can we know that you tested equally representative samples of each of these items? Other than the Light Cannon, which is clearly an inferior product, the differences - especially between the Speed Booster and the Lens Turbo, are quite subtle and could easily be explained by sample variations.

How do we know you didn't test a cherry-picked sample of the Speed Booster?  It's fairly common practice to use an internally screened sample of one's own product for benchmarking purposes.

brian wrote:

Since Metabones released the first general purpose m4/3 focal reducer in June 2013 several more products have appeared on the market. To my knowledge, there haven't been any systematic high resolution comparison tests of these focal reducers, so I decided to shoot a test chart and put together a matrix of 100% crops.

The matrix below shows 100% crops from the center, left side, right side, and all four corners of test chart images taken with a 50mm f/1.4 Nikon G lens (wide open) attached to: 1) the Light Cannon by Vizelex; 2) the Lens Turbo by Zhongyi; 3) the R.J. Focal Reducer; and 4) the Speed Booster by Metabones. The test chart used is a standard Resolving Power Chart available at low cost from Edmund Optics: http://www.edmundoptics.com/testing-targets/test-targets/resolution-test-targets/resolving-power-chart/1665 . Note that the chart illumination wasn't perfectly uniform, and was a little brighter on the right side. In each case, focus was adjusted for maximum contrast in the center of the field. The camera used was a Panasonic G6.

DISCLAIMER: I'm the designer of the Speed Booster optics.

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Brian Caldwell

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