There are stains in the corner of my pictures>>

[sjackal]

I noticed there are a horseshoe shape stain on the top left corner of my pictures during a recent shoot. At first I thought i could be my UV lens or the lens hood, I removed both but its still the same. I tried changing to another lens, its still there.

Some pictures have it, some don't, then I realised its the aperture size.

I did some test and discover that the higher the aperture number, the more obvious it is. At apertures below f4 its not there, at f6.3 onwards it starts to show faintly till f8 which is obvious, and at f16, it is very very defined.

What happened? Please kindly help! I will try to attach pictures later.

[sjackal]

Ok attach a pic. See the top left corner horseshoe shaped stain

[Octarine]

Originally Posted by sjackal I noticed there are a horseshoe shape stain on the top left corner of my pictures during a recent shoot. At first I thought i could be my UV lens or the lens hood, I removed both but its still the same. I tried changing to another lens, its still there. Some pictures have it, some don't, then I realised its the aperture size. I did some test and discover that the higher the aperture number, the more obvious it is. At apertures below f4 its not there, at f6.3 onwards it starts to show faintly till f8 which is obvious, and at f16, it is very very defined. What happened? Please kindly help! I will try to attach pictures later.

According you systematic tests (congrats for that, not many have such a logical approach) and the picture it seems that you have something at your sensor. So it's time for sensor cleaning.
You can consider a) DIY or b) bring to the respective service center of your camera brand.
a) Check the manual of your cam if it comes with an ultrasonic sensor cleaning. Canon 400D and 450D have it. Follow the instructions given in the manual to shake off the particle. If this doesn't help you'll need a stronger blow.
Get a blower (rubber, rocket shaped, about SGD 15-20), remove the lens, activate the sensor cleaning function in your camera (check manual!), hold the cam with lens opening down and blow gently into the cam. DO NOT stick the blower inside the cam or you might accidentally damage something. Once you have done a couple of blows deactivate the sensor cleaning (mostly: switch off the cam), put back the lens and to some test shoots. best is with f/22 aim at a white wall and use tripod. Then shift a bit to left or right and take 2nd pic. By comparing both pics you will see what is specks on the wall (will move) and what is left at the sensor (same position in both pics).
Repeat the procedure till the pic is clean again. If it doesn't help and the stains are still there you can continue DIY with wet sensor cleaning. But that's not so easy and if you are not confident in DIY things you better revert back to b)
b) - Check for the local service center and ask them to clean the sensor. Costs for Canon are about SGD 25 max.

[sjackal]

Thanx alot! Mine is Nikon under warranty, so I hope its free? Sorry for the double thread.