I did a screen shot of the first image of each set so I could compare them directly. IMO the Amotal and Ektar are so similar in almost every way -- including color rendition, skin tones, contrast, vignetting and even apparent focal length -- that they are quite difficult to tell apart. It almost looks like the same image was uploaded twice by mistake. I would have bet against this result, thinking that some of these characteristics would be different between the two lenses. On close examination there are differences, but they are surprisingly slight.
The Summar seems to be the odd person out. It has different color rendition, enhanced contrast (at least in some parts of the image), increased vignetting and apparently longer focal length. The impression of increased contrast might be the result of the increased vignetting making some dark areas toward the corners darker than the other lenses -- check out the darker logs and wall in the upper right quadrant. But the light sand is a bit darker, suggesting either lower contrast here or the effect of vignetting again. And this result of apparently increased contrast is exactly opposite of what I would have guessed in such an old uncoated optic.
I'll post the screen shots below for easy comparison. Brian if you prefer I not repost in this form, I'd be happy to delete. Just thought it might make comparisons easier.
Here's the order:
#1 Summar
#2 Amotal
#3 Ektar
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