Dirt on the sensor?

[Glenn NK]

Glenn - Nikon certainly recommends turning of the camera before changing lenses. Pg 25 on my D800/D800E manual says: "Be sure the camera is off when removing or exchanging lenses". I seem to remember the D90 manual having a similar statement.

I don't know about static charge build up on the sensor. That would be something that the manufacturers would want to eliminate in their design work; having a sensor acting as a dust magnet would not be a brilliant piece of engineering. Electronic circuits are easily damaged by static discharge, so I suspect that this is a non-issue.

Canon does not mention turning the camera off (5DII, pp 31, 32), but does when changing CF cards and batteries.

On the Canon forum (POTN) this has been discussed endlessly and the consensus is that the body can remain powered during lens changes. I've NEVER turned either of mine off during lens change.

Static charge - I agree that they'd want to eliminate it - and not just when the camera isn't powered. As you say, static discharge damages electronic circuits so I suspect there is no static charge at any time.

Another Urban Legend? I recall when the net was full of posts like: "Swiffers are poisonous - the chemicals killed my dog". Nonsense.

Glenn

[Mito]

Good news The splodge has gone. Several shakings and a good puff have got rid of it. I don't change lenses frequently but always take as much care as I can to prevent muck from getting in.
Thanks to all for all the information. I shall have a look round for a cleaning kit that is affordable for me.
Am I correct in thinking that the sensor is hidden behind what I think is a colour filter? I don't know what it is called. If that is the case the sensor is never touched.

[Manfred M]

There are a number of discrete elements sit in front of the actual sensor. In general, the contaminants accumulate on the AA filter of a camera.

In those cases of the cameras that don't actually use an AA filter like the Leica M lines or Nikon D800, the Nikon still uses a package that includes a number of elements including an IR filter in front of the sensor and I expect Leica has at least an integrated UV filter after the issues they had with the M8. The actual Bayer (colour) filter and microlenses are part of the sensor.

[nimitzbenedicto]

Good news The splodge has gone. Several shakings and a good puff have got rid of it. I don't change lenses frequently but always take as much care as I can to prevent muck from getting in.
Thanks to all for all the information. I shall have a look round for a cleaning kit that is affordable for me.
Am I correct in thinking that the sensor is hidden behind what I think is a colour filter? I don't know what it is called. If that is the case the sensor is never touched.

Hi, got rid of several specks the other day using the Nikon pen cleaner brush.
very light brushing strokes, 2 cycles only. and blew on the insides with the Nikon D200 turned upside down.

No more specks. So far no apparent damage.

HTH.