The affect of cleaning marks.

S

Sumo_du_Jour

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An average bloke's lens investigation.

Handsome devils? (see Two by Fifty.Jpg)
A new CV Nokton and Ole' Hazy (much loved) 1957 Summarit. Resplendent with bad cleaning marks on the rear element. With a magnifying glass heaps of pin-point spots, or bubbles are visible in the glass. I could expect worse for 48 year old glass.

Objective: does Ole' Hazy's affliction impact performance?

Technique: shoot a simple still life with both lenses, using the same exposure settings. Compare the results.
(( Pic test scene.jpg))

Processing: Kodak HD 200, domestic snapshot stock from the local grocery store, scanned at 4800dpi, post processing: minimalist. 100% crops converted to Jpeg for this post.

Comparison shots.
Can only fit a couple more images in a post, so there's the 30th at F11 set attached.

Conclusion: This average bloke can't see much in it. I have seen a flare and haze issue in bright sunlight with Ole Hazy, so he'll probably come out for low-light jaunts.

My limited understanding of things optic is greatly enhanced by the impassioned work of Erwin Puts, the straightforward studies of Sean Ried, the informed membership at RFF, many others at Photonet, Luminous Landscapes, and numerous on-line haunts. I'll leave thoughts of distortion and astigmatism to the learned crowd, who could no-doubt point out differences.
Comments appreciated.
 
The tricky part may be knowing *which* light conditions will end giving trouble and which not, but hey, that's part of the charm of using classics :)

But for those impressive cleaning marks, the photo looks quite good. While some people out there claim that marks on the rear element are more probably going to have a more visible effect, some others (KBCamera) say exactly the opposite.

So, the only real way is to use the lens and compare by yourself. For what I've seen, fog/haze seems to affect way more than cleaning marks.
 
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