Speck of dirt in Canon 70-200 2.8 IS USM Lens.

[elmo_2006]

I have decided to continue working with this lens.


I appreciate the comments and thank you.

[wickerprints]

Here's something I discovered.


Take any lens, and remove both end caps. If you take a strong flashlight and shine it straight through the lens barrel, you will see dust. It is everywhere. Even the "sealed" lenses have it. These things are not airtight, nor are they designed to be. Even hard drives are not hermetically sealed (though they do have a "breathing hole" that employs a particle filter). The dust is so small that you can't really see it unless you shine a bright light into the lens--which means it won't degrade optical quality, because in the course of taking photos, you never actually shine that bright a light source through the lens.


So in my view, something has to be really huge in order to make a visible impact on image quality; and it is only to the extent that dust particles inside the lens may be indicative of improper manufacturing or a lens defect that I think it should be serviced. If there was a hair in my lens, metal shavings in the barrel, or an air bubble in the glass, I would send it back because those things tell me the QC was inadequate, not because any of those things would make a noticeable impact on the image quality. However, a small speck of dust--even in an L lens--is not significant. Shine a flashlight through that lens and you'll be surprised what else you can see.