Your sensor will contain dust, eventually. Even self cleaning sensors eventually do collect dust. It looks like this:
To actually see this dust, as in the image above:
- Use BULB mode
- f/22 (smallest aperture)
- Wider angle
- Aim at a white surface, out of focus (use manual focus for this)
- Click and wave the camera about. Try an exposure of 3 seconds. If too dark, make it 65. If too light, make it two. And so on.
Once you have the image, that shows you the dust you have.
If you need to clean, there are solutions (pads, brushes), but use them with care. Start with a blower, then use the brushes, then use wet pads. A photo store can tell you the pros and cons. Risky, maybe – but I have been doing it for years with no ill effects.
I am scared to try, but perhaps I should give it a go.
Doesn’t a blower just blow the dust around inside the camera and it will settle elsewhere? Somehow you need to get it out. Maybe holding the camera upside down while blowing helps.
I almost never change lenses while I am outdoors so my sensor is pretty good.
Does the automatic dust reduction system in newer Canon cameras make a useful difference? It looks like a gimmick to me.
The system does make a difference. Big one. It is not 100% effective but much better than previous cameras.
The blower does do that, so indeed, upside down always, and also when changing lenses.
I guess I’ll see today and tomorrow (I am in Arizona and the skies are blue) how much dust I have in my 1Ds and 7D.