Originally posted by Rondec You could probably have an adapter that would not have auto focus capability and just transmitted lens data for one hundred-ish dollars, but add more functionality and price goes up.
Sony's NEX to alpha adapter sells for significantly above 300 dollars a unit.
I stand on no side of the fence, but again ... this is not true.
A (basically) 1:1 adapter is nothing but a macro extension tube or a TC converter w/o glass. E.g., the Tamron SDM/screw drive 1.4x adapter sold for about $100 and most of the price is for the optics embeded. A K mount "registration distance adapter" with full functionality would sell for well below $100.
The Sony adapter has an entire phase AF module, half transparent mirror, processor and maybe even a focus motor (I don't know if A mount has support for an in-body focus motor, the E mount certainly has not). It's an entirely different beast with a very specific target user group in mind.