Quote Originally Posted by Steve Smith View Post
Am I correct in assuming it takes the 'normal' view a lens would have on 35mm format and focuses the whole of that image onto a smaller sensor?
Yes you are correct. The only thing that this product purports to achieve is to take the "normal" view a lens would have on a 135 format and give you the exact same view (FOV, DOF, etc) on the smaller APS-C sensor.

If so, it seems logical. It's something I thought about a few years ago when I was temporarily a digital photographer - not as a business idea, just one of the idle thoughts I have occasionally!
It is very logical, and simple, theoretically. Simple enough that you and I could come up with it completely independently.

Some people might be querying the faster claim. It's because the lens now actually has a shorter focal length but the aperture diameter range stays the same. Simply, aperture (f No.) = focal length / aperture diameter).
Exactly. And, it's really NOT going to make the lens "faster" per se. Because we're dealing with a smaller sensor which, all else being equal, gives you more noise per square inch of the same size print, having a faster F value doesn't really give you an advantage over shooting with that lens on FF with 1-stop extra ISO.

That is, with everything else in the sensor technology (and processing technology) being equal, taking a 50mm F1.4 lens (on FF) and:'

(a) shooting it on an APS-C camera with this adapater as a 33mm F1.0 lens at ISO 100, 1/125s, and
(b) shooting it on an FF camera straight-up as a 50mm F1.4 lens at ISO 200, 1/125

should optimally give you identical results. Identical in terms of FOV, DOF, AND Noise levels.