Camera Labs

I recently bought a Sigma 70-20mm f2.8 DG HSM from a POTN member and to my unpleasant surprise, found this. I tried cleaning it but it's on the inside face of the front element. It seems that it does not affect image quality but I would like to know what this is.

so why didn't you checked the lens before buying it?

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Gear: Nikon D80, 18-105mm, 35mm F/1.8, 85mm F/1.8, SB-600
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I would forget about it if it doesnt affect image quality

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Nikon D5000 and D300 with 12-24mm, 35mm f1.8, 50mm f1.4, 60mm f2.8 Macro, 18-200mm, 17-55mm f2.8 (all Nikon)

mine has a similar mark, just a little smaller. it was there when i first got it so it's probably something from assembly

it doesn't affect the image quality so im not bothered with it.

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DeviantArt
Canon 1D MK3, 1x580EXII, 1x430EX
Canon 50mm 1.4 USM, Canon 100mm F2.8 USM
Canon 70-200 F2.8 L IS II, Canon 16-35 F2.8 L
Sigma 300mm F2.8

Canon Pixma PRO-9000 MKII

and a 17-40 F4L in a hundred little pieces

you people are easy buyers

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Gear: Nikon D80, 18-105mm, 35mm F/1.8, 85mm F/1.8, SB-600
Visit my work here