Upon thinking about it, I find yesterday’s corner color cast results with the M-mount lenses on the a7R pretty depressing. We’ve already seen that lenses long enough to require a lens collar – or even, I suspect, mounting to the tripod via a plate on the adapter — have a problem on the a7R because of shutter shake. Now we see that M-mount lenses as long as 50mm suffer from quite noticeable corner color casts on the camera.
What does that leave us with?
- The 75, 90, and 135mm Leica lenses, plus Zeiss equivalents
- F-mount and Canon lenses of 180mm or shorter, and not real heavy ones at that. Forget the Zeiss 135mm f/2, and the Zeiss 100mm f/2, since they both need you to use the tripod plate on the adapter to avoid putting too much strain on the a7R lens mount.
- The Sony/Zeiss E-mount lenses
That’s a slim slice of Leica glass. [Addition: As is pointed out in a comment below, I’ve reached my conclusions about the 50mm and 35mm focal lengths based on the lenses available to me for testing. Others have reported good performance at 50mm and 35mm using different Leica lenses.]
I’d just as soon use F-mount lenses on the D800E. The a7R offers better live view and the EVF, but using those lenses on the D800E allows mirror lockup, autofocus, and auto-diaphragm. I find auto diaphragm especially hard to give up in many situations; the last preset lenses I owned were a Komura 200mm and a Spiratone (remember them?) 25mm in the sixties, and I’m not anxious to return to those not-so-halcyon days, although I’d consider it a good trade if I could have my 20-something body back.
Then there are the E-Mount lenses. The full-frame E-mount line is barely getting off the ground, so there’s not a lot to choose from. The 35mm? I’d rather use an RX-1. The 55mm, when it finally starts shipping? Not my favorite focal length. And besides, I’m not ready to buy into a new set of lenses based on what I’ve seen in the a7R. Sure, it’s small, and I grant that the very nice built-in EVF is the wave of the future. But the haptics of the controls? Yuk. And the menus? Double yuk.
So that leaves me looking for some way to make 50mm and shorter M-mount lenses work, and I have a promising direction. The beta, as-is, don’t call us if you have any problems, Adobe Labs corner cast correction plug-in for Lightroom has a mode that may make the correction workflow tolerably easy, and eliminate the need for field record-keeping.
If you tell it to, the plug-in will scan a group of images looking for interleaved correction images, and will automatically use the correction images on adjacent (forward? backward? TBD) real images. My guess is that it does the detection based on average spatial frequencies in the images.
So, you’d find a scene, and make some exposures. Then, without changing the f-stop or distance, you’d slap a diffuser over the lens and make a correcting image. Then you’d move on and do it again. Sounds like it might work. I’ve ordered a couple of diffusers to try.
In the meanwhile, there’s comer color smearing to worry about. I’d had to go to a lot of trouble to fix the color casts and be left with unusable images because of the smearing. I’ll start testing that next.
This is not an easy camera to like.