Kenko vs Fotga Extension tubes with the 75-300 Mk ll The 75-300 with either make of tubes is ideally suited for medium magnification macro with very comfortable working distances. For things like butterflies, damsels, dragonflies and the like magnification is in the order 0.25x-0.33x with working distances of 33"-40" from the end of the hood, sheer luxury. Hand held on an E-M1 it works really well. Which set of tubes one considers is an individual choice, I tried both, but settled on the Kenko. Both sets of tubes are identical in size, 10mm + 16mm, and both do the same thing. However this is where the similarity ends IMHO. The Fotga tubes are inexpensive, one could say 'cheap' compared to the Kenko ones, but are value for money, one gets what one pays for. Price in the UK is £24 for the Fotga tubes, compared to £104 for the Kenko ones. I've had Fotga tubes that worked and Fotga tubes that did not, the electrical contacts were faulty and messages were not being passed from lens to body and back. A second set where they were so loose the lens almost drooped. The quality of one compared to the other is, IMHO, chalk and cheese. Fotga tubes are what one would expect for £24. I found mounting and dismounting to be 'snaggy' and not smooth, the locking mechanism like wise. I must be honest and say that I was not too confident about hanging my 75-300 on them. The Kenko ones are a different kettle of fish, quality is excellent. Mounting and locking is smooth and I have 100% confidence in them. Fotga 2 by Dave in Wales, on Flickr Details Lens Setting // Tube Fitted // Magnification // Working distance, end of hood to subject. 200mm // 16mm // 0.25x // 33" 200mm // 10+16mm // 0.26x // 34" 300mm // 10mm // 0.23x // 40" 300mm // 16mm // 0.28x // 36" 300mm // 10+16mm // 0.33x // 33" All dimensions are approximate, should errors be found please don't shoot the messenger.