At the end of today's shoot, I noticed two dark circular marks on an image, one on the top right and the second just above the centre. I did some tests and was concerned to find that the marks appear on every image, regardless of the lens I'm using. They are very noticeable in even toned areas, such as a blue sky, when viewed at 100%. Does anyone know what causes this and how to fix it?
Could be dust on the sensor. Use mirror lockup on your camera, turn it upside down, and use some air to blow the dust out (DO NOT USE CANNED AIR) - use an air rocket or something similar that doesn't propel a liquid.
Thanks, eveyone. From what you all say, I think it's dust. I've tried cleaning the sensor using my Canon 40D "clean sensor now" setting, but it hasn't worked. I'm away on holiday at the moment and don't have an air blower with me. I'll try to clean it manually when I get home. Looks like the next few days are an opportunity for me to put my new Canon S95 through its paces as a back-up!
PLEASE DO NOT TRY TO CLEAN IT MANUALLY IF YOU NEVER DID IT BEFORE. It should be done very carefully.
When I cleaned my sensor the first time I read lot of articles on the Internet on cleaning. Unfortunatelly, I used russian sources, so I can not share with you but for sure you can fild lot of text on the subject in English, as well.
In principle, there is ALWAYS some dust on the sensor (it is not avoidable) and there is no too much harm due to it. It is visible only if aperture is strongly closed (f/16, f/22. ...) and in any case it is easy to remove these spots using PhotoShop tools.
7d + lenses: Canon EF-S 15-85mm/3.5-5.6 IS USM & EF 100mm/2.8 USM Mac...
@ Adeliepenguin. Unfortunately, I don't know of a camera shop near me that offers this service. I live in Shropshire in the UK. Does anyone out there know of a shop within 50 miles of Birmingham that does?
Get a hurricane blower. It puts out a lot of air volume without using compressed air. Each time you change your lens, blow out the end of the lens that connects to the camera, as well as the cameras chamber. It also helps to lift up the mirror and blow the area around the sensor (do not touch the sensor just blow it off). This method should only be done in a dust free or low dust environment (not outside with the wind blowing by any means), but preferably inside a room or the interior of your vehicle.
I've used this method for years and have had to have the sensor cleaned professionally very few times. This method was recommended by my local camera shop repair and sensor cleaning guy. Works great.
IS, Canon 17-40mm L, Canon 100mm F/2.8 Macro, and, occassionally, a C...