Always been too proud to ask.

Sooty_1 (Critique Team)

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15 Mar 2013 - 10:35 PM

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When turned on, the sensor becomes electrostatically charged, and thus will attract dust. Turning it off doesn't automatically dissipate the charge, so turning it off, then immediately removing the lens will still allow the potential charge to attract any dust that is nearby and at a different potential to the sensor. More effective is to tilt the camera lens mount down so nothing inadvertantly falls in (or floats on an air current). The fact is, that dust is an unavoidable consequence of changing lenses (and of using zooms).

I would turn the flash off before removal, in case you short the x-sync when removing it, as it might give you a shock, but you don't need to turn off the camera. Some older flashes required an open flash to discharge the capacitor after you finished using it, as the dump circuits weren't particularly efficient.

I would (and do) turn the camera off when changing lenses with electronic contacts, as again, if you were to short contacts inadvertantly, it might cause unwanted effects in the circuitry.

Nick

Paul Morgan (e2 Member)

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15 Mar 2013 - 11:47 PM

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Quote: I've never switched off when changing lens. I cannot see any reason why this is an issue

If your camera has a built in dust shaker it makes sense to switch of before changing lenses.

Newdevonian

17 Mar 2013 - 9:55 AM

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Many thanks for all your comments. I have been switching off since the film days and since camera shutters were powered by battery. I had not considered the static on the sensor or the self cleaning aspects, so all good information.