Moonrise & Aurora

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I did a 30 second long shot without the lens and checked the sensor and saw some dust on my sensor (even though camera has sensor cleaning). I didn't see any defects on photos yet, but is it something to consider and take actions ASAP?

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possible duplicate of Should I be worried about getting dust inside my SLR? – John Cavan♦ Jul 7 '11 at 20:45
@John Cavan - dang, looked for that and couldn't find it. Too many 'dust' questions lol. – rfusca♦ Jul 7 '11 at 20:47
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When you say 30s shot without the lens, do you mean looking at the sensor while it's taken a photo on an open body? With the CMOS chip on like that while the shutter is open it's likely to attract dust to it as it has a current through it. You may have just made it dusty when it wasn't before :/ – Dreamager Jul 7 '11 at 22:39
You can check how much dust you have on sensor by setting high aperture and pointing camera, f.ex towards sky (with proper exposure) on mine I start see something from f16 and on f22 it is quite strong - but I wouldn't worry much about it, unless you have whole dune in your body. – Rafal Ziolkowski Jul 8 '11 at 7:17
I don't think it's a duplicate, the other question is a about getting dust on sensor while this one is about already having it. – Imre Jul 10 '11 at 7:11

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up vote 6 down vote accepted

Dust on your sensor happens to many of us, its not the end of the world.

If you're not seeing it on photos, I definitely wouldn't take drastic action. Order something like this rocket blower, set your camera to mirror lockup, and gently try to blow the dust off. You can also look at gentle liquid cleaning solutions.

If you are unable to remove the dust yourself and it becomes apparent in your photos, consider having your camera professionally cleaned by a shop or the manufacturer.

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I would advice against trying the cleaning solution ... if you can't clean the sensor with the blower, have it cleaned professionally. If you screw up, it's expensive to get it fixed. If the pros screw up, they have the resources to fix it. – david Jul 8 '11 at 21:11
Mirror lockup does not release the shutter, which needs to be open to clean the sensor. Holding the mirror open using bulb mode is also risky. If the shutter is accidentally closed it could strike whatever you are using to clean the sensor. Bulb mode also means there is current running through the sensor which can attract loose dust as well as causing dust already on the sensor to cling to it. Most DSLRs have a "manual cleaning" mode that will raise the mirror and open the shutter without energizing the sensor. Once engaged, the only way to release it is by shutting off the camera. – Michael Clark Feb 15 at 18:45
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You won't see any dust from a long exposure without a lens. The dust becomes visible when you take pictures with a very small aperture, like f22, and without the lens you get a very large aperture, like f0.5. The exposure time is not relevant, the dust doesn't get more visible from a longer exposure.

What you see might be dead pixels in the sensor. In that case there is nothing that you can do about them.

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He took a 30second exposure without the lens, so he will have likely got more dust into the camera due to the longer exposure. You are correct about the smaller apertures showing up dust more though. – ChrisFletcher Jul 8 '11 at 12:57
@ChrisFletcher: I think that you misunderstood my literal expression "you won't see any dust" as "there won't be any dust". What I meant was exactly what I wrote, i.e. that the exposure won't let you see the dust. – Guffa Jul 8 '11 at 13:06

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