At 2:20 PM -0500 1/12/01, Pierre Bellavance wrote:
>I've recently sold my 28-105 lens on eBay, and the buyer complains
>that there are specks of dust inside the lens.
>
>Should he worry about this, or is it normal in an 8 year old lens?
Hey - the lens you sold me had specks of dust inside it too.
Obviously you mistreat your lenses! I demand compensation! :)
Both of the lenses in question (28-105 and 100-300 4.5-5.6) do not
use internal zooming. In other words, when you zoom out or in the
lens extends or contracts. This sucks air and dust into it. Try
zooming the lens when it's not mounted and hold the base of the lens
near your face - you'll feel the displaced air puffing out. One of
the reasons the more expensive L series lenses are more durable is
that most of them use internal zooming and internal focusing.
I think the consensus has been that a bit of dust inside a lens
doesn't affect image quality at all. Smudges on the front element or
crud buildup on the rear element would, but that's another story.
- Neil K.
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