With the advent of sensor cleaning in newer bodies - does it matter which way up you hold the camera whilst it is cleaning? I understand that the sensor cleaning works by vibrating the sensor to knock the dust off, to stick to a "very sticky bit" - but are these very sticky bits all around, or only below the frame in landscape orientation?
This article on Pixinfo talks about a test that they have made between for cameras with sensor cleaning systems. According to that, the camera has to be upright for the sensor cleaning to be effective.
However, the test also suggests that for some cameras it doesn't matter much, because the sensor cleaning hardly works at all.
I was watching a video about the 645D and the Pentax rep mentioned, in the course of the interview, that when doing dust removal it is best to hold the camera in landscape orientation as level as you can to get the most optimal outcome. He also mentioned that it applied to all dSLR cameras with sensor shake dust removal, not specifically the Pentax ones. So... Since then, that's how I do it and I do it every time I swap lenses, seems to be working for me, I've had very little problems with sensor dust.
1Would be interesting to know why though. Most likely thing I can think of is that there is something stick below the sensor to catch the dust particles. Sep 27, 2010 at 16:49
@Matt: That was the reason he gave, that the sticky trap was at the bottom and any other direction would just land it on a surface that would transfer it back through camera movement.– Joanne CSep 27, 2010 at 18:13
This is uninformed, but my guess would be "no" because dust particles are tiny enough to be mostly unaffected by gravity (they are instead moved around by random motion in the air).
1Your guess is uninformed. The most sophisticated dust removal systems create air motion in the direction of the dust trap at the bottom of the sensor. They do this by the designed shapes of the moving parts when they vibrate. Feb 15, 2013 at 18:53
@Michael, it seems you object to the "random motion", which is fine, and the clarification is helpful. However, you actually speak in favor of my guess, which is that it's air motion, not gravity, moving the particles. It would be nice if your objection was both correct and courteous.– ReidFeb 19, 2013 at 17:46
My apologies if you felt I was being less than courteous. I only repeated your own assertion re: an uninformed guess. You are correct that Brownian motion is a factor, but so is gravity. It is both gravity and just enough minute air movement to overcome the Brownian motion of dust in static air that sophisticated dust removal systems use. Dust particles are much larger than air molecules more influenced by their own Brownian motion than gravity. In a pure vacuum on the Earth's surface dust will accelerate to the ground at 32 ft/sec^2 (assuming no electrical charge is also present). Feb 19, 2013 at 18:20
1A self-deprecating "this may be uninformed" is a lot different than calling someone uninformed. Clearly, yes, I felt you were being discourteous, and the "sorry if ..." is a classic non-apology. Anyway, I'd suggest you write an answer, since you have more technical content than belongs in comments.– ReidFeb 19, 2013 at 20:08
YES. It matters.
This is because the camera has a slight sticky pad at the bottom of the camera so when the sensor vibrates it will fall on to this little pad. If the camera is on its side or pointing up you just moving the dust around. If pointing down it just falls into your lens or mirror just to end up back on the sensor.
Rish is correct -- it's not just that the dust get knocked off the sensor, but they get trapped and not allowed to get back on. That's what the sticky surface is for. Hold the camera in landscape and level during cleaning. Sep 29, 2010 at 15:08
I imagine that if you were to orient the camera directly downwards, you would get the most effective "drop off" effect due to gravity, however the dust would then drop onto the shutter, and probably find its way back onto the sensor very quickly.
I just place mine upright on a table and let it do its thing.