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Old Dec 18, 2004, 3:11 PM   #1
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I noticed a black speck today inside my 28-135mm lens for my 20D.

Please excuse my poor knowledge of the names of the different bits of glass in a lens, but the speck seems to be on the inside of the glass nearest the camera end.

If I look through the lens at something bright I can see it clearly.

I've tried taking photos looking at a sheet of white paper at both extremes of focus but I can't see anything on the image.

Is there a test I can do to show it up, or should I just ignore it or should I take the lens back and get it replaced?

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Old Dec 18, 2004, 7:45 PM   #2
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take a picture of the paper at f/22, or whatever the highest you can go is....

the element nearest the lens mount is the rear element

i have dirt in 3 of my lenses, and i dont have a problem, i've asked people on here, and they said its fine, i did send one with most dust into nps, and they dent it back and said it's fine....

lenses are not air tight, there for they will get dust in them.....

and when you take the picture of the paper, you will notice ALOT of dust on your sensor too, and its nothing to worry about, if posible, id take it in to the local camera store and have it cleaned 2 a year....

good luck

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Old Dec 19, 2004, 5:01 AM   #3
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It's so close to the sensor and it'll be so far out of focus it shouldn't notice. If anything it'll show up as a very slight dark blob on the photos. But it'd have to be big for that.
If you're worried I'd suggest, other than the paper idea, that you take a picture of something with lots of close straight lines then view it on your computer. If they look straight and crisp then you have nothing to worry about.
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Old Dec 19, 2004, 11:51 AM   #4
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Thanks for the input.

I tried the white paper but couldn't see anything until I increased the contrast to +90%. There were some marks visible but not too bad.

Anyway I took it back to Jacobs in Leicester today and they swapped it without question.

After trying the new lens, most of the marks were still there so I guess that's dust on the sensor, but at least I have got rid of the large(ish) black speck.
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