Interestingly, the Kirk replacement collar for my 300/4 AFS did not perform very well relative to the Nikon stock collar, which is truly anemic. On my G1410 (see elsewhere in my galleries) the Kirk collar absolutely trounces the Nikon collar but there the tripod was adequate for the purpose. Here the 28mm legs simply are not up to the job and I think that is reflected in these tests.

Not yet posted to my site was an amazing test result involving a Wimberly Sidekick. This test was so bizarre I repeated it and got the same results. Using my G1228 (I had returned the Feisol to it's owner by that point in time), I get almost perfect images with the Nikon stock collar and foot, the Sidekick, and the 300/4. That just goes to show that vibration is truly impossible to predict and small changes in configuration can result in very unexpected results. With all that said, I'm not about to sell my Kirk collar. It's an aberration but worthy of some consideration.