I have been wondering that question myself. How does it get in there? I have some dust inside my 200-500. I think it was in the lens from the factory and just made its way onto the glass after I banged it around for awhile. It doesn't have any effect on the photos just bugs me when I look at it. Kind of like a picture hanging crooked on the wall.
Edit to add, SG, Any Word on a Spring Time Wisconsin GT?
My new 50mm F.18 lens has a couple of dust specks in it, but they don't show up in the pictures. of course, the lens only cost $70 bucks so I can't really complain.
No lens is truly sealed. They can't be, really. With moving elements inside, they have changing volumes between element groups (zooming, focusing), so they need to move air around. Where there is air movement, there can be dust entry. A little dust in a lens will never be detectable in photos. Dust that shows up on photos is almost always on the sensor (well, on the filter over the sensor, to be exact). A severely dusty lens might show decreased contrast, but you'd have to have outlandish amounts of dust in there for that.
I clicked a frame
to capture a moment before the moment's gone
All my shots
Pass before my eyes, a curiosity
Dust in the lens
All we have is dust in the lens
Same old spots
Just some dots i try removing endlessly
All we do
is chase lent around to set our sensors free
Dust in the lens
All we have is dust in the lens, oh Now, don't hang on
Nothing you can do and nothing you can try
(except 2-8)
And all your money won't a dust-free lens buy
Dust in the lens
All we have is dust in the lens
All we have is dust in the lens
Dust in the lens
Everything is dust in the lens
Everything is dust in the lens
The lens
Perhaps it's on your mirror, use a some type of dust removal (i.e. Giotto rocket blower)
Dust on the mirror will not show up on a photograph so longas the dust stays on the mirror. Once it shakes of the mirror and works its way around then itll get on the sensor and show up.
You could paint the mirror black and it wont affect what the sensor see's.
Besides hes convinced the dust inside the lense is the problem so i think sensor/chamber dust isnt even within the question.
I clicked a frame
to capture a moment before the moment's gone
All my shots
Pass before my eyes, a curiosity
Dust in the lens
All we have is dust in the lens
Same old spots
Just some dots i try removing endlessly
All we do
is chase lent around to set our sensors free
Dust in the lens
All we have is dust in the lens, oh Now, don't hang on
Nothing you can do and nothing you can try
(except 2-8)
And all your money won't a dust-free lens buy
Dust in the lens
All we have is dust in the lens
All we have is dust in the lens
Dust in the lens
Everything is dust in the lens
Everything is dust in the lens
The lens
Usually if it is in the lens it will not show in any photos because of the depth of field focua length between the sensor and the dust, same goes for minoe dust on the outer end of the lens. If it is on the sensor it will show especially at ssettings like f/20 to f/32.
.
I just bought a new Canon 70-200 f/2.8 L IS and it is full of dust. If I hold it up and look through just the lense I can see several large pieces inside the lens. It does not show in photos but frives me crazy thinking about a $1800 lens that comes dirty inside. Best of luck.
