Mark on the chip or lens?

[martcol]

Got my 10D and a borrowed lens (while I make my mind up). Noticed a mark on pictures with no detail (eg sky). At f32 it looks like a twig and at f5.6 just a faint blur.

I'm guessing that if there was a problem with the chip it would be on all images and because it changes with the f-stop it will be on the lens? I've tried to look closely at the glass but can't see anything.

Any thoughts?

Martin

[HoodedOne]

Maybe it´s something inside the lens !!!

[martcol]

But not on the chip, on my nice clean, brand-new, shiny chip? :O

If it's in the lens, I take it there's nothing I can do about it?

Cheers

Martin

[Cal Maier]

Martin,

I think you'll find that it is some dust on the camera sensor. If it is very noticable at f 32 and faint at f 5.6, it probably is on the c-mos sensor.

Digital cameras are plagued with this problem and no matter how careful you are when changing lenses you will most likely introduce dust in to the camera. I examine the back of the lens closely before attaching it to the camera body to try and minimize the amount of dust on the sensor, and it seems to help somewhat, but it's virtually impossible to eliminate this problem with day to day use.

Get a good blower(if you don't own onealready) and follow the cleaning instructions in the manual. When the mirror is locked-up before you use the blower you should be able to see any specks of dust on the sensor.

Good Luck!

Cal