AndyH wrote:
Since there is no glass involved, I don't think brand and price make as much difference in extension tubes as in other optics. Precision is important, but in my admittedly less informed opinion, I would go with the price savings on the Kenko.
Andy
Two important things. First, ensure the extension tubes purchased supports AF for your camera, and second some are looser and bit more wobbly than others. I know that on Canon camera's the Kenko extension tubes are less rigid then the Canon tubes, but of course the Canon tubes are much more expensive.