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Schneider Kreuznach 28 LS: poor corners perfomance or I'm too picky?

GrahamWelland

Subscriber & Workshop Member
I would have to defer to LS users vs D as I can only relate to the 28D version and my copy specifically. I know that with the D version there has been some sample variability.
 

dougpeterson

Workshop Member
That was our test and I'd say from both that test and subsequent experience that there is no meaningful difference between the 28LS and 28D. Both have significant field curvature across the frame such that a very very minor change in focus will change whether the edges or corners suffer more.

Both modestly improve at f/16 over f/11 concerning the extreme corners, but of course the absolute sharpness (e.g. sharpness in the center) will drop modestly on an 80mp capture due to diffraction. Both are handled quite intelligently by the lens corrections in C1 (I say "intelligently" to avoid saying "well" since lens correction can only do the best out of what it's given, it can't improve the underlying sharpness characteristics of the lens - only give you a smart way to sharpen the corners more than than the center using math which lowers the propensity to show deleterious artifacts of that sharpening).

Both are utterly smashed by the Rodenstock 32HR or 28HR. The 32HR can easily handle an 80mp sensor at f/8 (even a bit wider though DOF becomes a major practical corner) and can even do so with rise/fall/swing applied; it's a stupid-good lens.
 

dougpeterson

Workshop Member
@Sarnia - since you're using an Alpa, you have the option of mounting the lens in any of four orientations. So, if you're still having issues with corner performance, rotate the lens 180˚, reattach it, and shoot the same scene again, and see if the corner performance is identical or has 'moved'. If it's the latter then there may be an issue with the alignment of the front and rear groups.
Worth pointing out this is possible on any major tech camera. On an Cambo or Arca you would simply rotate the digital back mounting plate 180 degrees.
 

jagsiva

Active member
I had the 28D and for what it is I thought it was a fine lens. I ended up going tech and just to echo Doug, the 32HR is indeed a special lens. Even with movements, it shines. I have the CF, but I do think the lens is very usable without it.

In comparison, I have the 23HR and 40HR as well, but I always find myself reaching for the 32.
 

ondebanks

Member
There are some very nice medium format wide angle SLR lenses made but I think only the Mamiya / Phase 28 covers full frame 645.
The 24/4 ULD fisheye (Mamiya manual focus) covers full frame 645 and when de-fished, behaves just like a rectilinear 24mm lens. It's very sharp at all apertures, but does show lateral colour (however I think it's no worse than the 28mm excerpt that Torger showed above, which rather shocked me for a lens of that price and complexity). The lateral colour cleans up well in any software for automatically registering the 3 colour planes geometrically. Corner sharpness drops a bit too with de-fishing, due to re-sampling and stretching of the PSF (...but again, the 28mm corners I've seen are not that hot either). And there's zero vignetting, and no mucking about with centre filters.

Following Graham's lead, we could say that with a little extra cropping, the 24mm is just as great a 28mm lens as the "official" 28mm SLR lenses!

Now the tech-cam lenses are of course another story.

Ray
 
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