Actually, the rear retaining rings were taken down very slightly only on the leading edge where it might hit while still providing protection for the glass. Unmodified though, it did not clear on Jim's 5d (unshaved mirror) and that's when he asked me if I'd like to try for additional clearance since I had a 1-series. Fortunately for my combo, all is well in infinity-mirror land!
I'm not very familiar with how the typical wide-angle rear conversion method is done, but compared to my 58/1.2, there are distinct refinements. Makes me want to update the 58, haha!
The Rokkor is warmer. Both files were processed equally, but I needed to adjust color temp, exposure and eyeballed both images to match as best I could. I started off by applying Landscape and Daylight WB to the zuiko as the baseline and tweaked slightly from there. The Rokkor has better foreground corners, the zuiko is stronger in the center from edge to edge and holds slightly more detail all the way to infinity. At F8, it still has darkish corners, but it progressively goes away stopping down further. It's true - do not be afraid to use the Oly 21/2 down to F16, that's when it starts to catch up with the Rokkor in the foreground corners. Lastly, I've confirmed what I read previously about the Rokkor being a little longer than 21mm. The Oly 21/2 is a tad bit wider at the edges. Toggle both images back and forth quickly. The difference is pretty obvious and kinda makes the Zuiko look distorted as a result from being that much wider, haha.
Just got in my latest conversion from Jim and haven't been able to shoot it on my other bodies yet, but here's a quick test shot, 1/80th, ISO1600 on the T1i. CS3 Exif reports f/1.8 (tagotech chip does not allow intermediate values), 1/85th, but that's wide open on the MC Rokkor 85/1.7 @ 1/80th on the CR2.
The new EF mount looks exactly like the one on the 21mm, this latest generation of Jim's is really sweet.
