Sure thing Ben, it can be very useful for stills too.... The thing is that for stills, there are alternatives using fast AP-c lenses through adapters e.g. the Tokina 11-16 for instance, while in video, where much of the sensor area is inactive, problems like vignetting, corner resolution or edge distortion are much less, if you add the flexibility of the rocker zoom that exists in all recent Nex mount cameras (vg-30/900, eh-50, fs-700) which can double the FL with insignificant loss of quality, the advantage is huge... A Canon 24-105 or a Nikkor 24-120 can cover the entire FF range from 26 to 230mm/265mm (FF equivalent) being of f2.8 without their disadvantages being enhanced further as it happens if the full sensor is used... same thing with the 24-70mm zooms, that will be able to cover 26-155mm at f2.... wow!
A 70-200 2.8L IS would now be used as a 49-140mm 1.4
giving an especially welcome advantage in low light shooting in theaters, concert halls and night clubs.
I think this lens designer has done a pretty good job at shrinking the full frame image on to the APS-C size sensor with essentially no practical loss of detail in the full frame. No miracle but a pretty useful tool for low light and non-intrusive photography.
As to noise, that entirely depends on the camera. Some Nikon and Canon SLRs have a quiet mode which is more silent than most NEX cameras, for example.
Undeniably Jerome has a point here... the device seems perfect in theory, but OTOH, no lens is perfect... we should expect the better lenses to be benefited and the poorer ones to have their disadvantages exaggerated. However, the lower analysis (2k) and the smaller frame used in video, undeniably benefits video users more than it does stills shooters... besides, the fact that the image area is squeezed by exactly one stop (i.e. it's root square smaller or 0.71x) still leaves some of the extreme edge and corners out from a FF lens with respect to the APS-c area of NEX (which is 0.65X the FF area), so that some lenses that are problematic only on the very far edges and corners (especially in video frame for the later) will still benefit a lot... What I haven't solve yet, is if the DOF area shrinks by one stop... or if a 24mm lens at (say) f2.8 real used aperture, will become a 26.3mm (image area FF equivalent) of f2.0 with 24mm f2.8 DOF though... DOF will remain the original one ...no? As it will when the rocker zoom is used ...no? Never the less, I will buy the thing for my (recently added - I replaced the 3ccd cameras I was using up to now) NEX mount videocameras...
What I haven't solved yet, is if the DOF area shrinks by one stop...
I've used the NEX5N but not in a concert. It's claimed that there's an additional synthesized shutter sound in the NEX3 that can't be shut off! The Sony RX100 as in the Ricoh GXR are pretty well undetectable with their sounds switched off. Anyway, the NEX5N Leaf Shutter seemed very much quieter than my 5DII and that's one shot after another. I understand that the NEX7 shutter is even quieter. With the 5DII, AFAIK, one can only delay the loud mirror slap, but not keep on shooting.
Have you checked out BlackMagic's pocketable videocamera yet? I wonder if Metabones will make a mount for that!
That's what I thought... in fact it will be A900 and 50mm f1.4 = 54.5mm AOV with f1.0 aperture (only as exposure is concerned) for the same DOF as is on the A900... hence there will be root square of depth of field increase for the actual aperture that is used for exposure (f1.0 in this case). Still there will be 0.6 of shallower DOF than if an APS-c lens was to be used for the same AOV and the same light passing through aperture.The depth of field of a given lens at a given aperture on full frame will be roughly the same as the depth of field of the same lens on an APS-C camera through the adaptor.
Example: Sony A900 and 50mm f/1.4 wide open = Nex7 and adapter and 50mm f/1.4 wide open.