28mm / f4 Centre Frame (100% Crops)
|Nikon 28mm at f4 (centre)||Olympus 28mm at f4 (centre)||Zeiss 28mm at f4 (centre)|
As you might expect, centre frame all three contenders justify their reputations, and handily display all the trademark characteristics of theire respective brands: the Nikon contasty and neutral; the Olympus warm and Leica-like in its soft, detailed shadow rendering; and the Zeiss delivers icy-cool colours, extreme accutance and that limpid 3D quality. I must confess to favouring the Contax here.
28mm / f4 Corner
|Nikon 28mm at f4 (corner)||Olympus 28mm at f4 (corner)||Zeiss 28mm at f4 (corner)|
Now this was unexpected: I was prepared for moderately soft corners at this aperture, but I wasn’t expecting the Zeiss to be this bad – its resolution loss is quite graceful compared with the Olympus, but look at the vignetting! And I wasn’t ready to accept that the Nikon AIS would perform so strongly at this aperture. The first sample I tested gave similar results to the Olympus, but this sample is so much better, and just humiliates the Zeiss.
You will notice that the Olympus has messed everything up by being a little wider than the other two, making absolute comparison more awkward. It’s nonetheless evident that is comes a tied second with the Zeiss, some way behind the Nikon here. Incidentally, these crops are about 25 pixels out from the extreme corner of the frame – I blame the 5D viewfinder.
28mm / f11 Centre Frame
|Nikon 28mm at f11 (centre)||Olympus 28mm at f11 (centre)||Zeiss 28mm at f11 (centre)|
I swear these have had the same sharpening applied: the Zeiss has such extreme accutance that even this relatively modest 150/0.5/3 USM almost tips it into the realm of oversharpening, whereas the Nikon and Olympus by contrast look as if they could take some more! From f8 to f11, this lens is so sharp that USM is almost unneccesary. Photographers and hobbyists spend so much time obsessing over getting their lens to look sharp enough, but this one is almost too sharp. It’s interesting to look at the histograms for these three images:
|Nikon 28mm at f11 (histogram)||Olympus 28mm at f11 (histogram)||Zeiss 28mm at f11 (histogram)|
Zeiss optics are sometimes criticised for being too contrasty, but the 28mm Distagon has captured highlight information smoothly all the way to extinction, despite its appearance! This histograms also illustrate the way the Olympus lens has extracted a nicely gradated range of shadow tones, unlike either of its competitors. It wouldn’t be hard to bring in the white point on the Nikon and Olympus shots and interpolate the missing information, but the end result wouldn’t be as right as the Zeiss image which delivered all that information to the sensor in the first place. Having said that, look how abruptly it has clipped the shadows….
It also occurred to me that the Nikon and Olympus shots would look a lot more like the Zeiss with extra sharpening. Here’s what happened when a USM of 125/0.5/5 was applied to the Nikon and Olympus crops only….
|Nikon 28mm at f11 (sharper)||Olympus 28mm at f11 (sharper)||Zeiss 28mm at f11 (unchanged)|
This also demonstrates what you can do with high-resolution, low contrast lenses in post production (Leicaphiles rejoice). Just for fun, let’s apply the same sharpening to that already eye-wateringly sharp Zeiss shot…
Ouch!! but we digress…
28mm / f11 Corner
|Nikon 28mm at f11 (corner)||Olympus 28mm at f11 (corner)||Zeiss 28mm at f11 (corner)|
At f11 (and f8) the Zeiss really sings. But once again the Nikon is very close, and a notch above the Olympus every time. I wasn’t expecting any of these lenses to exhibit significant colour aberration; here’s a 200% crop of the extreme frame edge:
|Nikon 28mm/f11 (200% frame edge)||Olympus 28mm/f11 (200% frame edge)||Zeiss 28mm/f11 (200% frame edge)|
No major problems here: but once again just look at the Zeiss. You may have heard the urban myth about Zeiss lenses rendering more of a scene in focus than other lenses at any given aperture – well it’s true. They somehow manage to create a greater depth of field than other lenses. The effect is almost paranormal in the 21mm Distagon.
Finally, distortion and vignetting: here’s the Nikon 28mm full frame at f4: rollover the image to show the Zeiss and Olympus versions:
Final round clearly to the Nikon which achieves that rarest of objectives: perfect geometry. The Zeiss has a little barrel distortion, the Olympus has a little more. I suspect the Zeiss is the only true 28mm here: the Olympus is more like a 27mm and the Nikon a 28.5mm.