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Do lens elements typically have to match?
Old 03-25-2018   #1
dmitrizzle
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Do lens elements typically have to match?

I've read that on old Kodak Retina cameras you should make sure that all lens serials match as replacing a lens from another body cold spell some sort of trouble.

Is it typical for lens elements to be matched so stringently? Or can I replace a lens from another camera of the same model/make with no issues?

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Old 03-25-2018   #2
citizen99
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You would have less confidence that the performance was as originally intended by the manufacturer, on the other hand under most circumstances you probably wouldn't be able to detect a significant difference in aberrations unless you carried out optical laboratory bench type tests.
I suspect that it would be more critical the more complex the lens type.
You would need to check whether the focus had shifted significantly.
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Old 03-25-2018   #3
peterm1
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I recall reading that Leica would assess individual lens elements as some would be over the specified parameters a bit and some under and that by mixing and matching they could optimize the final completed lens. Maybe I read this in Irwin Putts book? I cannot now recall the source but I think I recall him discussing this either in that book or in an article about manufacturing of lenses, what it takes and how they controlled costs.

I suspect it might have been a pretty ubiquitous German thing for better quality lenses by high grade manufacturers but I am not convinced it was always necessary - if the bulk of lens elements were within specification there would be no need. Mixing and matching would be more a way of controlling costs by avoiding the need to scrap that part of the production run in which elements were close to but slightly outside quality parameters. It has also been part of the "magic" surrounding certain Leica lenses (the old 50mm Dual Range Summicron is one such example) that it has been said that these lenses always got special treatment of this sort. This would no doubt be due to the close focus which would impose extra demands on lenses (and of course in due course, also became part of the marketing hype and legend.)

These days with computer controlled manufacturing I would have thought it is not so necessary as quality should be able be tightly controlled as elements are manufactured.
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Old 03-26-2018   #4
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Several years ago while removing my Sinar from its case, the lens adapter had come lose from vibration in transit. As I swung the camera up to mount on my tripod the lens came lose and hit a concrete floor. The rear cell hit first resulting in 2 broken elements and a bent shutter. The front cell was undamaged fortunately. The lens was a 121 Super Angulon.

I kept my eyes open and eventually found another that had sustained similar damage but on the front grouping and the shutter appeared ok. I mated the two good cells in the new shutter and gave it a try. Sadly the images were terrible due to two issues. This shutter was warped Aldo and the front and rear cells weren't optimized for each other.

I wound up sending the lens to Schneider (century optical in California). They replaced the shutter and adjusted each cell to match by adjusting individual groupings spacing. The result was a lens that performed like new. The tech said the cells were close to a match but out of spec with each other to give mediocre performance until optimized.

I talked with the tech at length about this. He stated older lenses had matched elements which were tweaked for optimum performance as a total lens. He said random groupings generally could not be combined to produce an optimum lens.

The tech told me that this was not true of modern lenses like the Super a Angulon XL and Symmar XL for example. Through mew technology in grinding elements, even aspheric, random elements most often are perfect matches. Now there's little need to hand pick elements for high performance.
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Old 03-26-2018   #5
johnnyrod
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I replaced the ruined rear element of a 50mm f2.8 Tessar in a 1960s Zeiss Contessa LKE with the one from an LK, ostensibly the same but non-RF (like Zeiss made any two things the same). The focal length of the elements were the same, but the pictures, while fine, are not so sharp; I was disappointed in particular with my last film, even at smaller apertures and faster shutter speeds (focus and RF are accurate). I need to dig out some pics from similar cameras to compare, but with the old element, despite flaring badly in bright light, it could produce sharp results.
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