Hi all,
I just checked in to see what people thought about the Metabones "speedbooster", announced with some fanfare a few days ago, and am surprised that it hasn't come up yet. I had for a long time thought this was such an obvious interesting tool that the fact it didn't exist must imply it can't be done. Now apparently it has been done. So why not earlier? There was some suggestion that it can only be done with mirrorless but I don't get that.
Anyway, if you haven't heard about it just check dpreview or google it. It is basically a reverse teleconverter which demagnifies the image. The result is a larger FOV (you no longer need to apply the APS-C crop factor to the focal length) and a gain in apparent aperture.
The first adapter will allow you to use Canon EF lenses for use on Sony APS-C NEX bodies, by applying a 0.71x demagnification, yielding a 1 stop speed gain. A version for m43 olympus and panasonic bodies should come later. These could have up to a 0.5x demagnification and 2 stop light gain. So my cheap but good 35mm F2 would become a 35mm F1 on m43. It don't think you get the shallow depth of field of a true F1 lens but the two stops of light will help negate some of the drawbacks of the smaller m43 sensor under low light.
A potential counter argument for UW use is that without adapter you would use a shorter focal length m43 lens to get the same FOV as a FF lens, and shorter focal length normally translates to closer minimum focus (an UW advantage of m43 that is not often mentioned). But for lenses that can already focus close, like the 35mm F2 or 100mm macro, it should be interesting.
If image quality is not affected, and that is the claim/expectation, then I would be very interested. Both to keep using some of my Canon lenses after a switch to m43 and to see what the extra light can do. The question is, will FF lens diameters fit into mirrorless camera ports?
Bart
