I recently acquired direct from Fotodiox USA, a Fotodiox Pro Contax 645 to Hasselblad XCD adapter to use with my Contax 210mm/f4 lens. Whereas the auxiliary diaphragm is a very neat way to sidestep the electrically actuated auto-diaphragm on the Contax 645 lenses, it is causing another problem. When using the adapter with a 645 210mm/f4 lens, at any aperture smaller than f8 on the auxiliary diaphragm, I start to get vignetting. By f22 this is so severe as to render the image unusable and I would actually get better results with substantially less vignetting by using a Leica R 80-200mm lens designed for 35mm use, on my Novoflex LER-HAX adapter. Sadly there does not seem to be any alternative to the Fotodiox adapter. It would have been better if they had been able to make an active adapter to allow the Hasselblad body to control the auto-diaphragm on the Contax 645 lenses or even lock the lenses into manual rather than auto-diaphragm.
Wilson
Wilson