Used lenses - "extremely minor amount of dust" should I worry?

Crotal Bell

Crotal Bell

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I've seen many used lenses from reputable stores where they refer to the above quote.
I presume this does not affect the quality of the pictures, or can it?
 
It seems to be boiler plate.

It's presumably more about covering themselves description wise if a customer finds some dust they missed - or that appears because it moves (particularly as a result of transit).

You could run an experiment by finding an absolutely sterile lens that had no dust - sell or part ex it to one of these vendors. And then wait to see how it is described when it is put up for sale. I'd be pretty certain it would be described as having dust.

As a general statement - no - minor dust doesn't usually affect the image.
 
Dryce said:
It seems to be boiler plate.

It's presumably more about covering themselves description wise if a customer finds some dust they missed - or that appears because it moves (particularly as a result of transit).

You could run an experiment by finding an absolutely sterile lens that had no dust - sell or part ex it to one of these vendors. And then wait to see how it is described when it is put up for sale. I'd be pretty certain it would be described as having dust.

As a general statement - no - minor dust doesn't usually affect the image.
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Thank you. That helps a lot. Probably just covering their butts then.
 
Crotal Bell said:
Thank you. That helps a lot. Probably just covering their butts then.
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Yes, it seems like it, never had a lens from a reputable dealer that has had any noticeable dust on it.
Camera sensors are a bigger concern, often found dust or smudges.
 
I once bought a lens from a reputable dealer for a bargain basement price because it had oodles of dust in it .

I used that lens for several years without any trouble. I suspect that, if the dust is far enough away from the focal point, it is irrelevant. Some dusty lens examples...

Okehampton Shopping Arcade 5D IMG_9927.JPG
Arcade Milsom Street Bath 5D 5020.JPG
Canon Eos 5D_two 9516.JPG
 
Most will have some in, since it is of organic origin as a rule it can be a start point for fungus which is a much more serious issue - but specks of dust inside a lens are unlikely to have any effect on image. There is an outside chance of a bit more refraction effect looking towards strong light.
I recall an experiment where they stuck debris on the front element of lenses and it was hard to see it was there until they went up to about the size of a 1p piece.
 
Even if a used lens has no dust visible on the elements at time of the pre-sale inspection, by the time it's been posted and delivered, a small amount of dust can potentially have been shaken free during transit and be visible on the lens elements when it arrives. I think this is probably the reason 'minor dust' is mentioned in the sales description by some traders, where none may actually be visible.
 
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Virtually all lenses exhibit some evidence of dust.
It would seem only extreme levels of dust soften an image sufficiently to noticeably degrade images.

Any lens will draw in and redistribute dust, over time, as the focus or zoom is extended and contracted, in a bellows like effect
Even sealed lenses suffer from minor dust levels as it can be introduced when off the camera, and can come from the interiors of back caps that pick up dust when they spend time unattached. and probably in a linty pocket.

Lenses with a Major amounts of dust should probably be avoided, as it demonstrates a general lack of care for the lens. Though of it self is unlikely to make the lens unusable.

Interior dust always looks worse than it really is, as it is magnified in size by the front lens elements.
large amounts of dust has its worst effect when illuminated by direct light falling into the lens. this could potentially cause slight haloing and misting of the image, but it would have to be very bad to do so. In a majority of such cases it would simply soften the image contrast slightly. (That can actually be beneficial in some high contrast situations)

Dirty and damaged front surfaces of lenses and filters are usually far more harmful to image quality, In extreme creating a mist like effect.

Most of all these effects can be minimise by using an effective lens hood or shading the lens. using undersized hoods is less effective.
 
Mr Badger said:
Even if a used lens has no dust visible on the elements at time of the pre-sale inspection, by the time it's been posted and delivered, a small amount of dust can potentially have been shaken free during transit and be visible on the lens elements when it arrives. I think this is probably the reason 'minor dust' is mentioned in the sales description by some traders, where none may actually be visible.
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Conversely dust can be shaken free from the lens surface and settle elsewhere within the mechanism, during transit. Some lenses and cameras now have adhesive strips in them. to catch floating dust and debris. This is perhaps more to keep dust off Sensors than off lenses.
 
bovey9 said:
As others have said it will not affect the picture unless the dust is huge. I remember when I first started shooting weddings I had a Bronica lens that looked like the hoover had been emptied in it.
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A good way to lower the contrast between the brides dress and a dark suit. :runaway:
 
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Terrywoodenpic said:
high contrast situations)

Dirty and damaged front surfaces of lenses and filters are usually far more harmful to image quality, In extreme creating a mist like effect.

Most of all these effects can be minimise by using an effective lens hood or shading the lens. using undersized hoods is less effective.
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Can you post any real world evidence of this or links showing this and any info on in what circumstances IQ degradation can be predicted?

Just to be clear, I'm not being argumentative or denying the issue it's just that I keep reading this on forums but I've seen limited to no real world evidence. Not that I've gone looking for evidence but in threads where people have mentioned this I don't remember seeing any examples posted. I routinely used filters on lenses for protection for years, decades even, and I agree that putting an additional piece of glass/plastic in front of a lens could affect image quality but on the other hand look what can happen to a front element before IQ is noticeably degraded. The only issue I was ever aware of was if there was a light source in the frame but apart from that I don't remember seeing anything... and I am a pixel peeping nit picker. It could be that I've just been incredibly lucky but that seems unlikely as does me missing IQ degradation caused by filters. I have a biscuit tin full of filters I've used in the past with, apart from the light source issue, just about zero evidence of any issues so I suppose I could do my own tests and see if I can see anything going on but to save me doing all that I'd appreciate any input from anyone who has seen real world IQ degradation caused by a decent (a decent one, not a name you've never heard off knock off costing peanuts) filter.

I stopped using filters for protection years ago and luckily I've not had any lens damage. My most used filter these days is a +4 close up filter, branded as Kood.
 
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woof woof said:
Can you post any real world evidence of this or links showing this and any info on in what circumstances IQ degradation can be predicted?

Just to be clear, I'm not being argumentative or denying the issue it's just that I keep reading this on forums but I've seen limited to no real world evidence. Not that I've gone looking for evidence but in threads where people have mentioned this I don't remember seeing any examples posted. I routinely used filters on lenses for protection for years, decades even, and I agree that putting an additional piece of glass/plastic in front of a lens could affect image quality but on the other hand look what can happen to a front element before IQ is noticeably degraded. The only issue I was ever aware of was if there was a light source in the frame but apart from that I don't remember seeing anything... and I am a pixel peeping nit picker. It could be that I've just been incredibly lucky but that seems unlikely as does me missing IQ degradation caused by filters. I have a biscuit tin full of filters I've used in the past with, apart from the light source issue, just about zero evidence of any issues so I suppose I could do my own tests and see if I can see anything going on but to save me doing all that I'd appreciate any input from anyone who has seen real world IQ degradation caused by a decent (a decent one, not a name you've never heard off knock off costing peanuts) filter.

I stopped using filters for protection years ago and luckily I've not had any lens damage. My most used filter these days is a +4 close up filter, branded as Kood.
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Filters, per se, are not harmful. Dirty ones most certainly are.
While I do use high quality protection filters they are kept spotlessly clean and free of smears. It is these finger marks and smears that are so damaging to image quality. Dust is rarely an issue.

While it is still possible to buy poor quality filters that are not optically flat,, I would suggest few people here would fall into the trap of buying them. It is also important that they are as well coated as your lenses, so as to reduce the possibility of internal reflections. That all being said and done, they should have no significant effect on image quality at all.

The best modern thin multi coated filters, are a perfect match for our digital lenses.
 
Terrywoodenpic said:
Filters, per se, are not harmful. Dirty ones most certainly are.
While I do use high quality protection filters they are kept spotlessly clean and free of smears. It is these finger marks and smears that are so damaging to image quality. Dust is rarely an issue.

While it is still possible to buy poor quality filters that are not optically flat,, I would suggest few people here would fall into the trap of buying them. It is also important that they are as well coated as your lenses, so as to reduce the possibility of internal reflections. That all being said and done, they should have no significant effect on image quality at all.

The best modern thin multi coated filters, are a perfect match for our digital lenses.
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So with common sense and care most filters, unless they're awful, wont create noticeable IQ degradation?

I always saw filter care as being the same as front element care, ie. Keep it clean and free of stuff including fingerprints, spots and streak marks.
 
Dust..pah. 5d classic is a dust magnet. Used to be a problem, but editing software can sort that nowadays.
I've chased dust on lenses trying to get rid, but in reality, it's never really showed up on pics.
Ongoing problem, dust is everywhere, and as soon as you take the lens cap off, electrostatic charge attracts it.
 
bish789 said:
Dust..pah. 5d classic is a dust magnet. Used to be a problem, but editing software can sort that nowadays.
I've chased dust on lenses trying to get rid, but in reality, it's never really showed up on pics.
Ongoing problem, dust is everywhere, and as soon as you take the lens cap off, electrostatic charge attracts it.
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I used to clean mine when I got home but even then if I tested it before going out again the chances are that there'd be more contamination. As much of this comes from inside the camera the 5D must have been slowly disintegrating. I took mine abroad on holiday once and when I got home I was just cursing it as I sat there cloning contamination out and this is without changing lenses.
 
The biggest issue for me is water or snow on the front of a lens, as I take pictures in any and all weather :D You have to watch that as it can be shot ruining.
 
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