The lens I've been using on my infrared converted NEX 7 for the past year has been the Zeiss Touit 12mm which in turn gives me about 18mm in full frame. I wondered yesterday what that same lens would produce on the Sony A7r.
First some comparisons. My NEX 7, IR produces files that are 6000x4000 (350 ppi 16 bit RGB, 137.40 MB). Likewise my A7r (using a 35mm 2.8 or 55mm 1.8) produces files that are 7360x4912 (360 ppi, 16 bit, RGB, 206.90 MB). So what happens when I use the 12mm on the Sony A7r?
The Sony A7r has the ability to automatically switch between APS-C and full frame lenses ( menu, second from top left looks like a wheel then over to the 5th screen and second down to APS-C Size Capture which offers the choice of On-Auto and Off my camera is normally set to auto). What this does is offer the choice of shooting an APS-C lens like the Zeiss Touit 12mm either in a cropped mode or full size. The full size will of course produce vignetting which can then be cropped out; but is it worth it...
12mm APS-C Size Capture "Off"
Crop of the file above
APS-C Size Capture "Auto"
I resized each file to better fit the web to 9x6 at 100 ppi. Both files were shot at f/2.8 1/100 ISO 400 handheld.
This was just a fast test last night to answer my own question of how well the Zeiss Touit 12mm would play with my Sony A7r and if it was worth the added effort of shooting with the APS-C Size Capture turned off. My short answer is yes it plays well and no I'd just as soon keep the APC-S capture on auto.
Forgot to add the aspect ratio was set at 3:2. Questions?