I think for that price you will find they will not have contacts on the tubes to allow AF and Auto
metering...you will have to use manual focus as well as manual
metering/
aperture setting. If I'm correct in the identification of them they can only be used on
lenses that have a
aperture control setting ring on the
lens itself as the
aperture values cant be set with the camera.
I have a set of these and dont find them a problem, just have to do it all the old fashioned manual way...it's not hard and the results can be amazing.