[drb5]

I seem to have one single bit of dirt, somewhere in my camera and i was wondering if someone has had something similar.

It is in the very centre of pics, but the higher the aperture i go, the less defined it becomes. So basically at f22, it is at it's clearest.

Any ideas where it is, as i can't find it?

[paulyoung666]

sounds as though it could be on the sensor itself , does your camera have a self cleaning sensor or not ?

[T0MAT01]

It's probably on your sensor.
At smaller aperatures (like f/22) the light rays are more parallel so it shows up more because the light can't get around behind it.

A rocket blower should shift it, but if it doesn't then you might need a sensor swab or you can get a shop to have a look at it for you.

HTH.

[drb5]

Thanks guys. By taking the lens off the body, should i be able to see the sensor? I'm not clued up to the workings of these things at all.

It's a 40D, so the shake isn't shifting it.

[Yandros]

Originally Posted by drb5

Thanks guys. By taking the lens off the body, should i be able to see the sensor? I'm not clued up to the workings of these things at all.

It's a 40D, so the shake isn't shifting it.

There should be a sensor cleaning mode, which will cause the mirror to be raised (on my Nikon , you set the mode in the menus, then press the shutter release to lift the mirror). You'll then see the sensor exposed on the back wall of the camera.

A rocket blower should be your first tool to try to shift a dust blob, but don't put the end inside the camera body and don't touch ANYTHING inside, particularly the mirror, as it's very delicate.

Read the manual and follow the instructions carefully

If this doesn't shift it, you may need to try a sensor cleaning brush (eg artic butterfly) or sensor swabs. To be honest though, unless it's a HUUUGE blob, it's probably not worth it for a single spot.

[T0MAT01]

Originally Posted by drb5

Thanks guys. By taking the lens off the body, should i be able to see the sensor? I'm not clued up to the workings of these things at all.

It's a 40D, so the shake isn't shifting it.

When you take the lens off you can only see the mirror. The sensor is hidden behind that. Like Yandros says you have to put the camera into sensor cleaning mode and you'll need a full battery before it lets you. Then it'll lift the mirror up and uncover the sensor so that you can try and shift the dust. Make sure the opening is facing down so that the dust doesn't fall back into the camera.

[tdodd]

Originally Posted by Yandros

A rocket blower should be your first tool to try to shift a dust blob, but don't put the end inside the camera body and don't touch ANYTHING inside, particularly the mirror, as it's very delicate.

FWIW, when I use a Rocket blower, I usually put the camera on a tripod with the body facing downwards a bit and the lens still on the camera. Then I swtch the camera into manual cleaning mode, remove the lens and then, very carefully I do put the tip of the blower into the body, very close to the sensor but not touching it, and then I support/brace the nozzle with my left hand against the lens mount aperture and I'm then free to blow with all my might with my right hand. The nozzle has maximum effectiveness and there is no risk of accident.

What I would not do is wave the nozzle loosely around without securing/bracing it against the body with my left hand.

Also, FWIW, I've had my 40D since September 2007 and I've never needed to perform a wet clean to date. However, I very rarely stop down below f/8 and never below f/11, so maybe I'm just not seeing muck that might be there. Using f/22 on a crop body camera like the 40D is a sure way to get soft images through diffraction softening. You can see the effect in this album of test shots....

Picasa Web Albums - Eezy Tiger - POTN - Diffra...

[drb5]

Thanks guys, i'll give it a go.