Dust in the lens

Neilmack

Neilmack

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There seems to be a regular preoccupation with specks of dust inside a lens, both on the small ads here, and elsewhere.

I suppose with the growing complexity of lenses (especially zooms) which have groups moving relative to one another (and thereby creating suction) it's an increasing problem. But minor obstructions in an optical system have a negligible effect on resolution (after all, reflecting telescopes work despite 30% obstructions!) and, although dust may lower contrast very slightly, that's hardly a problem in a digital context. Most serious planetary imaging (the most demanding of all applications?) is regularly done with obstructed designs. My own 55mm f2.8 Micro-Nikkor is afflicted with a shovel load of detritus, but even so, it remains searingly sharp, and I'm going to to have to buy a Zeiss Milvus to out-perform it.

So, while dust shouldn't be there - and a new lens should never have it - in real life it makes bugg*er all difference. Dust happens.

Or can anyone demonstrate a real-life problem that results from it?

Neil
 
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If I was selling a lens, I would mention the amount of dust just to reassure the buyer that there was not too much. I have a lot of second hand lenses and all have a smattering of dust but none enough to worry about.
 
It does seem to generate a lot of hang ups in the second hand market. Some use it as a bargaining tool, some use it’s absence to drive up a price. Unless it looks like the inside of a dyson it’s not really going to affect your lovely pictures. Fungus on the other hand......
 
I have a lens for sale right now that has a dust spot on one of the inner elements. It's a 35 1.4 that 'breaths' when focusing, so it's not that surprising to me over time that it's taken in some. But I did make a point about it in the ad, you know you'll get complaints otherwise. I know that it doesn't affect the lens performance and has zero impact on images, but not everyone does. Some beginners maybe, might imagine that it will show up in images, or that the lens is somehow faulty because if a bit if dust.
 
Will the presence of dust on the elements inside a lens affect the second hand value and/or saleability of that lens? If you wanted to buy a used lens and could find and afford one without any internal dust what would you do? I have no further questions.
 
Mr Badger said:
Will the presence of dust on the elements inside a lens affect the second hand value and/or saleability of that lens? If you wanted to buy a used lens and could find and afford one without any internal dust what would you do? I have no further questions.
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Personally I'm more put off by scuffed, abraded or worn bodies, evidence of rough handling. You can't do anything about that - in principle you could at least pay someone to do something about dust.

But always with a second hand purchase, the question is how much the premium for a flawless example, how much the discount for a compromise. I'm not suggesting that a dusty and a clean example of the same lens are of equal value - only that the dust thing has been fetishized in a way that suggests many folk don't understand the objective issue.
 
Mr Badger said:
Will the presence of dust on the elements inside a lens affect the second hand value and/or saleability of that lens? If you wanted to buy a used lens and could find and afford one without any internal dust what would you do? I have no further questions.
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I can guarantee you that a lot of 'mint' used lenses that sellers claim to be spotless, will have dust particles inside. It's almost impossible not to over time, unless the lens has remained inside it's original box, and at least never been changed out in the field. I prefer up front, honest sellers who point out even the tiniest flaws. You know you're getting exactly what it says on the tin. If I want mint, I buy new.
 
Cagey75 said:
I prefer up front, honest sellers who point out even the tiniest flaws. You know you're getting exactly what it says on the tin. If I want mint, I buy new.
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When selling on eBay, I find that listing all faults, including inconsequential ones, results in a higher price.
 
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