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No background in optics, physics or serious photography, but I am curious: What sorts of effects or "feel" does an ancient lens like this typically generate, and why? For instance, will the lens elongate, fade, or gather microscopic pitting?



My money's on that this lens is a Cooke Triplet http://en.wikipedia.org/wiki/Cooke_triplet which was (and is) a fairly neutral lens design.

There is some astigmatic aberration as well as vignetting visible in the photos provided, but it's possible that this lens was intended for a smaller image circle than 24x36 sensor in the 5DmkII. All lenses will have astigmatic aberration and vignetting at the edge of their image circle (which is normally outside the photographic media the image is being projected onto).

This lens is uncoated and highly susceptible to lens flare. As I understand it, many lenses before the 4-element Zeiss Tessar also tend to have more pronounced flare than later lens formulas. You can really see this in some of the photos.

Overall, it's neat little lens and I would shoot it in a heartbeat. It looks very sharp in the center with gentle fall-off near the edges. The owner could go a long way to get the most out of it by crafting a little lens hood for it -- it really helps with older lenses like this.

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And this lens is likely to be f5.6 or slower - it's a lot easier to make a 35mm f5.6 design than a modern f1.2 !

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f/5.0, the link said.

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One of the major difference is lens coating. Uncoated glass reflects roughly 7% of light per element. On a simple normal-length prime like this it may not be a huge issue, but you would see a major difference with a longer focal length consisting more elements.

Visually, coated lenses yield more contrast. In the case of more modern (usually after the 70's) multi-coated lenses, there is also a UV-reducing layer that maintains more detail at a distances due to minimized haziness.

Some of my favorite examples of a classic, uncoated lens showing its effect are from the Lewis Hines photos of the Empire State Building construction.

http://en.wikipedia.org/wiki/File:Old_timer_structural_worke...

There is some obvious dodging and burning done to this print in particular (the worker has been darkened compared with the cityscape in the background) but notice how much the detail fades with distance.

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