Okay, did a quick test, with just one image, and clearly more testing needs to be done -- it appears the Mitakon does not fare well at distance wide open, so appears to be corrected for close focus which of course makes sense. But here are some crops for you to compare. Note that these are all in-cam jpegs straight out of the cam, crops made in CS with no post processing of any kind added.
First let's look at the whole image for reference:
Now some center crops from all lenses at around f8 -- I say around because I used the Metabones adapter at "3" to stop down the ART and Nikon 50/1.8, so it's only approximate for the Sigma and Nikkor:
Nikkor:
ART:
Mitakon:
Now sides at f5.6/MB3:
Nikkor:
ART:
Mitakon:
First thing to note is the exposure differences in the center crops while the sides seem very close, other than to assume that it is a result of falloff and then the camera averaging across the frame. Next to note is the ART is the superior lens, which is no real surprise. What is somewhat of a surprise is that the Mitakon essentially equals the Nikkor in resolution here and both hold up pretty well in this situation -- doubtful we'd detect a huge difference until we printed the images large. Note too that the ART is a tad wider than the other two.
And here are the wide open comp centers:
Nikkor:
ART (Edited for refocus):
Mitakon (Edited for refocus):
Now the sides:
Nikkor:
ART:
Mitakon:
(Edited after refocus) What's interesting is how well the ART fares here now that I've refocused it and the Mitakon. The ART is the clear winner, even great at the edges, with the Mitakon being worst -- though let's not forget it is almost a full stop more open than the ART and nearly 2 stops more open than the Nikkor. Next oddity is the ART side actually appears to do essentially as well at the sides wide open as it does at it's center, which is pretty remarkable I think. The Nikkor sides render about the same as center and not really impressive. The Mitakon again worst optically, but again at 1 and 2 stops more aperture.
Interesting note on exposures. All were ISO 100 and taken in similar light within a few minutes. The Mitakon at f0.95 was 1/640th, the ART at f1.4 was 1/400th, or about the difference we'd expect given extra falloff in hyperfast lenses, but the Nikkor also came in at 1/400th -- it is possible the light changed as the Sun would have been rising slightly during this time, or it has even less falloff than the ART. Clearly the Nikkor image is about 1/2 to 2/3rds stop under exposed from the ART, and the Mitakon is another 1/3rd over the ART centrally -- all of which would explain the shutter speed differences almost exactly -- but then one needs to ask why the Sony can't meter them more closely? Perhaps a deficiency in the way the Sony meters adapted lenses? Clearly I would need to do a more scientific test to determine the cause of all this -- and I'm not going to bother! But I thought it was interesting to note in the wake of the earlier discussions of actual lens "speed" or light transmission that if all three of these frames were "normalized," it appears the lenses would perform at very close to their respective apertures as re light transmission centrally
End of day, no big surprises. The Nikkor is a 1.8 "kit" 50 for the Df, the Mitakon is uber fast, and the ART is designed to be great all over. Obviously the Mitakon works best wide open at typical closer subject distances (and lower light levels) as seen from my "Santa" shot above -- and more the type of distance where one would use it at -- but still holds it's own pretty well at distance when stopped down. The Nikkor is best stopped down to at least f2.8, and the ART is pretty exceptional for how it would be used from wide open up close to distant and stopped down for landscape.
My personal takeaway is the Nikkor is small, light and plain vanilla. I'll likely box it back up in it's factory box and keep it ready to sell with the Df body when that day comes. The ART remains a great -- nay, superb! -- all-around lens for my Nikon bodies and if needed to be pressed into use on the A7r for landscape. However, this thread is really about the Mitakon. The whole reason I got it was for looks and to shoot it wide open on the A7r, and so far I am not at all disappointed :thumbs:
~~~
Some additional final thoughts...
Here are a few more images for talking points. The above full image is from the ART at f5.6, obviously sized down to 900 px for web. Here is the Mitakon full image at f5.6 and wide open sized to the same 900 px. Interesting to note the thin DoF and oof separation efect of f0.95 is visible even at this reduced size, and not unpleasant (at least to my eyes) in this view -- speaking for myself, I wanted f0.95 for it's overall effect and feel I got even more than I hoped for
:
And I'll make one final comment about size -- the ART is a beast, and more-so with the Metabones adapter on the A7r; by comparison, the Mitakon is smaller and better balanced on the A7r:
Mitakon:
ART/Metabones: