Internal dust

[nikonbob]

What is the consensus here on the effect of internal dust in a lens on the image quality it produces. I mean dust and not haze or fungus. My own thoughts are that aside from being unsightly it has little effect on image quality. I have heard that it may cause more flare in extreme cases.

Bob

[kiev4a]

Internal dust among the front elements of a lens causes little, if any, problem. Around the rear elements is a different story.

[Peter S.]

Hi Bob,

I have a fair amount of internal dust in my 2.8/80 Zeiss S-Planar.

I examined the first slides very carefully. The resolution throughout the entire frame is limited by
that Nikon LS-9000 scanner (i.e. just a bit below the 4000 dpi nominal resolution). And I also doubt that a noticeable amount of light will be scattered by the dust particles.

I am firmly convinced, dust does only affect the monetary value of a lens.

Best regards
Peter

[David Silver]

I agree, I have my share of lenses, not only with (what some people would say is) significant dust accumulation, but also with a mold spider of two, and they're all sharp, sharp, sharp, with no evidence of light dispersion. I think people worry when there just seems to be SO much dust...but the spread of the particles is misleading. If every bit were placed in one solid spot, it would usually not even equate to one percent of the total element surface, even at a smaller aperture. Haze and broader patches of mold are another issue, since you're talking about covering larger percentages of element surface. Still, I've had lenses (and still do...one particular Summicron 35mm f/2 I keep on a Leica M2 as my ready lens) with noticeable haze that still performed perfectly. I think Ron makes a VERY important point. Dust, haze, whatever, it is all MUCH more potentially effective if it's along the inner surface of the rear elements.