The Coastal Optical 60mm is a great lens for infrared, but it’s too long for a lot of landscape use. I’m shooting handheld around the house, and I don’t like to do double-row stitches that way. So I’m looking for something wider.
28mm is a nice focal length for landscape. It’s probably the most versatile wide angle lens for me. Why not the 35? I don’t have anything against that focal length; I just don’t consider it a wide angle lens. The diagonal of the 35mm format is 43mm, so 35 is a wide normal lens, and 50 is a long normal lens, the way I look at it.
I set out to test three candidates. I will eventually get around to testing them in the infrared, but I’m waiting for some filters to arrive. I figure if they’re bad in visible light, they won’t be any good in IR, and if they’re good in visible light, they might be good in IR.
The first lens is the Leica 28mm f/2.8 Elmarit-M ASPH. This is truly a long shot, since it’s had bad corner smear on every alpha 7 camera I’ve tested it with. The next is its R-series brother, the Leica 28mm f/2.8 Elmarit-R. The M-series lens is of 2013 vintage, with all the fancy stuff that modern optical engineers can do. The R-series lens is from the 1980s. The third lens is also an older one: the Nikon 28mm f/1.4 D. This lens has a great reputation, and, after Nikon discontinued it, sold on eBay for way more than its original sale price.
The test protocol:
I mounted a RRS L-plate to the a7II, clipped it in landscape orientation into an Arca Swiss C1 head which was attached to a set of RRS TVC-44 legs. I focused all the lenses at f/2.8. I lit an Imatest SFRPlus target with a Paul Buff Einstein strobe set to 2.5 watt-seconds, for the f/2.8 shots, 5 ws for the f/4 ones, 10 ws for the f/5.6 ones, following that progression until I got to f/16. the narrowest opening shared by all three lenses. I set the ISO to 100, the shutter speed to 1/125 second, the shutter mode to 3-second delay and electronic first curtain shutter (EFCS). I made a series with the target in the center, and one with the target in the upper right corner, focusing on it in each location.
I developed the images in Lightroom 5.7.1 with default settings, exported them as TIFFs, and measured on-axis MTF50 in both the vertical direction — horizontal edges.
The M-series Elmarit:
The center is pretty good, but the corners are awful at wide apertures, becoming acceptable at f/11, where the center is beginning to roll off. If I were to use this lens on this camera for landscapes I’d be stuck with f/11 all the time.
The R-series Elmarit:
A little better in the center, and a lot better in the corner. Looks like a winner in visible light.
The center performance at f/2.8 is incredible. The corner, not so much. It looks about the same as the Leica R lens at the other apertures.
So far, I have two winners. I think for most uses, the Elmarit-R is the better lens — smaller, lighter. The Series VII filter is a pain, though.
[Added 2/22/15: The Elmarit-R has a lot more artifacts when the sun is in the frame, and more flare in general, than the Nikkor. I’m now using the Nikkor for IR work in preference to the Leica.]