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Does anyone know why there are these two versions of the non-automatic Nikon extension tubes? My Googling the matter yields nothing.
I noticed that in the earlier set, the A tube is very much like the K1, except that when mounting a lens, it does not rotate the lens 60 degrees, so it would be nice to use for close work with the 16mm f/3.5 fisheye - the built in lens shade would not vignette the corners like the K1. However, it does interfere with the electrical contacts on modern bodies.
Nikon claims the K2 is incompatible but doesn't say why, I've seen web sites that claim it interferes with the AI follower mechanism, but perhaps the earlier tubes are so ancient that they were not considered.
I'll probably go ahead and relieve the interference on the A tube with a grinder, the AI follower is in the clear.
Here's a website that shows both sets but not the differences:
Kevin Are any of the caps swollen, that's a sure sign! I'd change them all out.
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