From gegebenm occasion, I would like all those who are interested in this extender, to point out that the part is not suitable for every objective here. Only subsequent internet searches brought to light the following: Canon EOS series cameras have a so-called initial aperture of 5.6. Ie the smallest aperture transmitted from the lens must not exceed 5.6. Now, if this extender is used on a lens with smallest aperture 4.0, at its aperture value increases by two levels, ie 8.0 aperture. This is transmitted from the extender to the camera. Since this value is now greater than 5.6, no longer works for Canon cameras autofocus. Although I shoot more than 20 years, to me, the term Aperture is beginning have never experienced. Canon may have its reasons for this limitation, however, I find it reprehensible that is nowhere pointed to that fact. Thus, with the beginning of Aperture 4.0 named as compatible with this extender Canon lenses eg itself. I was therefore unfortunately no choice but to return as part of this, because in spite of the excellent optical performance, I do not want to dispense with the Auto Focus at this price.
