Forgotten in its old age

by Aditya

submit your photo


Hall of Fame
View past winners from this year

Please participate in Meta
and help us grow.

Take the 2-minute tour ×
Photography Stack Exchange is a question and answer site for professional, enthusiast and amateur photographers. It's 100% free, no registration required.

I was reading this answer where it mentions, "..it's a lens that can lose sharpness as it ages.." and was wondering if this is true and if yes, true for all lenses. Reasons as to why this happens and ways to prevent it if possible from a consumer's perspective would be great to know.

Please note, I am not talking about general wear and tear, or dust inside the lenses, nor am I talking about fungus in the lens.

share|improve this question
2  
Dont forget people generally loose the quality of their eyesight as they age ;) –  NULLZ Apr 8 '13 at 23:44
    
Found the statement. Quote "you have to be careful about buying the 100-400 used; it's a lens that can lose sharpness as it ages and gets bumped around. Newer units seem both sharper and more resistant to that.." –  Esa Paulasto Apr 9 '13 at 7:08
    
Thank you community for your enthusiastic responses. And amazingly enough, you all are correct (I added an answer from Nikon Support to confirm for sure). And for the difficult part of choosing an answer, I just chose one. –  Regmi Apr 10 '13 at 19:10
    
As the person Esa quotes above, let me comment as well. When speaking specifically to the 100-400 it's all about wear and tear and internal dust. So the real answer to this question seems to be "Yes, but since you exclude all of the conditions that might cause it, by your definition of the question, the answer is no. Except it does happen..." –  chuqui May 1 '13 at 6:10

6 Answers 6

up vote 15 down vote accepted

Given that you have explicitly disqualified fungus and dust inside the lens, then the answer is no. A lens will not "naturally" lose sharpness with age. Glass is glass. It is a fixed medium, and assuming a 100 year old lens is in good condition without any extraneous wear and tear like fungus, dust, or a strong enough jolt to misalign one of the internal elements or element groups...a lens will not lose sharpness with age. A 100 year old lens should perform just as well at 100 years old as it did on day one.

One thing that probably should be pointed out is that lens design has improved over the years. While certain classic designs are often held in lofty positions as they were revolutionary in their time, they may not be the best designs still today. New materials sciences, (frequently pioneered by Canon...such as fluorite elements or diffractive optics), even other general innovations like image stabilization, multicoating and nanocoating, aspheric and apochromatic lens elements, etc. have all lead to progressively improving sharpness over the decades.

With improved lens technology comes improved image quality. Even if a 100 year old lens is in pristine condition, it likely lacks the purity of glass that a modern lens has, probably lacks multicoating and probably even a single coating, and each lens element may not be as precisely aligned as we can do today. Two similar lens designs, one from a century ago and one from today, would likely not be directly comparable. The modern lens design should be producing much higher image quality than the century-old lens.

That does not mean the old lens as "lost sharpness", however...it just means it doesn't compare to a modern lens design that's benefited from all the modern advancements in materials and optical sciences.

share|improve this answer
3  
You say glass is glass, but glass isn't completely solid, it's amorphous. Very old windows (e.g.) in churches are thicker at the bottom than at the top because of this. So to me it wouldn't be unimaginable that you get a minor sharpness deterioration after very long times (100 years plus). –  akid Apr 9 '13 at 7:09
6  
@akid the church window thickness is a myth: en.wikipedia.org/wiki/Glass#Behavior_of_antique_glass the glass was installed thick-side down in the first place. –  c.cam108 Apr 9 '13 at 7:45
    
@c.cam108 Thanks for clearing that up :) –  akid Apr 9 '13 at 8:11
3  
There are some other parts besides the glass to consider, though: how do coatings and glues fare over time? Glues can become brittle and allow elements to separate, effectively creating new surfaces for diffraction. Can coatings deteriorate with age? –  Dan Wolfgang Apr 9 '13 at 15:31
2  
Even properly stored in an appropriately controlled temperature and humidity environment, the sealing between elements can, and often does, degrade. They can turn opaque or they can allow air into the tiny gaps between elements. In both cases this affects the lens' resolving power. –  Michael Clark Apr 10 '13 at 20:52

I confirmed this from Nikon Support to get an official answer to the above question:

"Thank you for contacting Nikon Support. No, a lens will not lose sharpness with age. The optics, glass will not age, however the seals, coatings and glue may.

ref# 130409-001818"

share|improve this answer
    
You should add this to your original question. –  Peng Tuck Kwok May 1 '13 at 4:13

The reason a lens would loose sharpness would most likely be because of wear and tear, dust, or fungus. I would think the glass itself is unlikely to warp unless faced with extremes in temperature.

I imaging if you kept a brand-new lens in a dust sealed, climate controlled environment, it would stay sharp for quite some time. But most lenses will need service or repairs to stay at their best.

share|improve this answer

You ask whether a lens can lose sharpness over time, but then go on to say:

Please note, I am not talking about general wear and tear, or dust inside the lenses, nor am I talking about fungus in the lens.

Which are exactly the reasons lenses lose sharpness over time. So the answer is no - once you exclude all the factors which causes lenses to lose sharpness over time, lenses don't lose sharpness over time!

Clearly fungus on the surfaces of elements will degrade performance. Dust will too, but to a lesser extent. The other major factor is wear, lens elements are ground to very precise specifications likewise the position and alignment of elements is very important. Any shift in the position of lens elements over time, as a result of wear in the mechanical portions of the lens body (zoom or focus mechanisms) or knocks which cause parts to become dislodged, will degrade image quality.

Aside from surface effects (scratches and the degradation of coatings) the glass elements themselves will not degrade except in some rare cases (such as lenses with thorium added to the glass which brown over time).

For validation of the idea that lenses don't inherently lose sharpness, look a Panavision. Panavision is a company that rent their own very high end lenses and cameras to the movie industry. Renting out their own gear means they take a slightly different approach to lens design.

Repair and replacement are both profit generating enterprises for most camera manufacturers, i.e. when you send you lens in for repair once it's out of warranty they will make a profit on the work done. Likewise when you replace your old lenses.

Any time Panavision spend repairing their lenses is pure loss as those lenses are not available for rental. Likewise replacing lenses only costs them money. As a result lenses are designed to be easily maintained, easy to disassemble and clean. Elements are not fixed in place but sit in adjustable mounts with grub screws that can be turned to correct tiny errors in positioning as the lens barrel wears.

As a result they have been renting out the same lenses for location shooting in extreme environments for decades, and they're still as sharp as the day they were first made.

share|improve this answer
    
What about 'slumping'? Glass is a liquid, albeit a very viscous one. Won't it slowly change shape with time? –  Ron Lussier May 1 '13 at 3:51
1  
@RonLussier: An urban legend. –  JohannesD May 1 '13 at 15:54

There is one factor not yet mentioned by any of the other answers: separation of elements glued together. As a lens ages the glue that holds some elements to each other can degrade, allowing air to infiltrate between the two lens elements. The areas with air will refract light differently and affect the overall sharpness of the lens.

In the context of the quote, I think it is more likely to infer that certain lens designs are more susceptible to misalignment and de-centering due to the wear and tear of normal usage. The EF 100-400mm f/4.5-5.6L IS with its push-pull zoom is one such lens. The EF 24-70mm f/2.8L, with the centering and tilt adjustments just behind the front element in the barrel that extends when zoomed, is another. You can read Roger Cicala's blog on the differences between it and the newer EF 24-70mm f/2.8L II here. Roger is CEO and technical guru at LensRentals.com which sees a lot of lenses with wear and tear, both from being heavily used and being bumped around by UPS and/or FedEx twice between each time they are used.

share|improve this answer

Since 100year old lenses can still be sharper than your average kit lens, I don't see this as an aging issue. "objectives" consist of many lenses, typically 4-15, in groups, and these are carefully places in a constellation that can be misaligned through heavy wear - like hard bumps. This - except fungus, excessive dust, misting, etc., is the only way I can see it losing sharpness.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.