Micro Four Thirds Focal Reducer Shootout

Started Feb 20, 2014 | Discussions thread
dougjgreen1 Veteran Member • Posts: 3,382
Given your clear vested interest in the results......

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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