This is true, but then Sony seems to goes out of their way to break compatibility...Spillicus wrote:
I've heard another wild, totally unsubstantiated rumor along those lines, but slightly different, that goes like Sony are pricks and wants to charge Sigma for the information necessary to make Sigma lenses compatible for A-mount. Rather than pay, Sigma just tries to reverse engineer it, but they don't quite get it right.
Nikon doesn't want Tamron and Sigma lenses to be cheaper overall, but they really don't want Sony-mount Tamron lenses to be cheaper than Nikon-mount Tamron lenses. That would push people towards buying into a Sony system instead of a Nikon system. That way, Nikon makes money on cameras, and in many cases, eventually makes money on lenses. It would be very standard practice for a company like Nikon to include something like a Most Favored Customer clause for customers buying Nikon-mount lenses from Tamron as part of licensing the lens mount.Why would Canon and Nikon want 3rd party lenses to be cheaper? Nah.Alternative explanation #4: Canon and Nikon have market power, and pressure Sigma and Tamron in some way.
I started out photography with mostly Tamron lenses. I now shoot almost all manufacturer-brand lenses (one Tokina in the mix -- but it's rather good). Many people do transition away from Tamron and Sigma as they mature. There is a very noticeable quality difference between manufacturer-brand glass and either Tamron or classic Sigma (I haven't tried the highly-reviewed contemporary Sigma glass much). A bunch of people on dpreview told me so at the time I was buying Tamron crap, but I didn't listen. From the number of people who warned me, I doubt my story is uncommon.