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 p.69 #11 · Voigtlander 40mm f/1.2 Nokton Review | |
Quick report on the Elpro 4 vs. f=2m Proxar for improving up close sharpness wide open on the 40/1/2CV.
First, at close distances (0.5 to 2 meters) nailing the focus wide open using either the EVF or rear LCD is incredibly hard. The focus that gives you max. contrast (least axial color) is NOT the sharpest focus and I think this is what can cause some focus accuracy issues. Sharpest focus appears to actually be where there is a fair amount of green axial color. Magenta axial color is not nearly as sharp.
Second, since I could not get an extremely patient live subject that would stay perfectly still for the good part of an hour, I used a ISO 12233 Test Chart printed to 13x19 size taped to a convenient wall. Did not care too much about parallelism to the focal plane of the camera since I was just interested in certain points on the test chart that I focused against. Still I had the test chart pretty parallel to the camera sensor.
Third, my up close test methodology was flawed in theory, but easy in practice as I first selected a focus distance (0.5m, 1m, and 2m) w/o any macro add-on lens and used a macro slider to adjust the focus. I then kept the camera at the same distance from the test target and re-focused to evaluate IQ. The better way to do this would be to have the same test target image sizes for each condition, which is the way one would actually use such an add-on lenses, but the image sizes were pretty close.
I evaluated sharpness dead center and 1/2 way to the right border of the frame for each lens condition and re-focused each time to remove field curvature effects.
So what's the upshot of all of this, short of showing images to back up what I'm about to say:
@2m Center
Naked 40/1.2 - extremely good, but hard to focus
Proxar - (needed focusing at infinity mark on lens) was great - no secondary color
Elpro 4 - could not focus this far out (as expected)
@2m 1/2 To Right Border
Naked 40/1.2 - OK, definite fall-off in sharpness
Proxar - (needed focusing at infinity mark on lens) was really bad - not sharp and lots of secondary color
Elpro 4 - could not focus this far out (as expected)
@1m Center
Naked 40/1.2 - good, but hard to focus
Proxar - needed to be focused to ~1.9m and was pretty good
Elpro 4 - needed to be focused to ~2.8m and also was pretty good
@1m 1/2 To Right Border
Naked 40/1.2 - OK, definite fall-off in sharpness
Proxar - needed to be focused to ~1.9m and was pretty good (way way better than 2m)
Elpro 4 - needed to be focused to ~2.8m and also was pretty good, about the same as the Proxar
@0.5m Center
Naked 40/1.2 - good, but hard to focus
Proxar - needed to be focused to ~0.6m and was pretty good
Elpro 4 - needed to be focused to ~0.66m and also was pretty good, about the same as the proxar
@0.5m 1/2 To Right Border
Naked 40/1.2 - OK, definite fall-off in sharpness
Proxar - needed to be focused to ~0.6m and was pretty good (way way better than 2m)
Elpro 4 - needed to be focused to ~0.66m and also was pretty good, about the same as the Proxar
So,
For 2m distances the Proxar is great in the center, pretty bad off-center
For 1m distances both the Proxar and Elpro 4 are great in the center and pretty good off-center
For 0.5m distances both the Proxar and Elpro 4 are great in the center and pretty good off-center
From 1m in I did not see a noticeable difference between the Proxar and Elpro 4 with the caveats that I didn't keep the image magnification the same between images.
But the big question is are these worth it over the performance of the naked 40/1.2?
Short answer is only if you are inside of 1-1.5 meters and if very close the Proxar seems to be just about as good as the Elpro.
Consider the above preliminary as hopefully later on today I'll post images to back up my conclusions.
The Proxar -
Pros: Price, multi-coated, short, same OD as lens, can adapt easily back to 58mm filter thread
Cons: Odd size, needs extraction, and a bit of work to get mounted properly. Not good off-center at ~2m subject distance.
Elpro 4 -
Pros: Achromatic doublet, no need to re-mount (unless you can't live with the thickness or OD), good performance across it's max to reasonably close distances.
Cons: Expensive, not multi-coated, 55mm is an odd size for adapter rings, etc., makes the CV noticeably longer
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