Long exposure noise reduction

When I shot my entry for the stairs competition I did notice something odd with my K20D.

I was lying beneath my camera on tripod which was adjusted to keep the camera a bit over the ground, pointing upwards. I took different exposures with mirror up (2 s delay) and shake reduction disabled (with the switch). The shake reduction setting shouldn't make a difference at the 2 s delay setting.

What caught my attention was that between the end of the exposure and the appearance of the image on the camera screen there was a distinct noise audible. And noise is the right word, i.e. there were no distinct frequencies that I could make out.

My suspicion is that during that time (i.e. during the 'exposure' of the dark frame) the shake reduction is active.

So the fortnightly competition is a good opportunity to check it out for yourself and see if your camera shows the same behaviour.

Prieni

...and first prize in the "most creative plug for the fortnightly competition" category goes to Prieni! Top marks

It's a serious question, though

If so it wouldn't matter since it only records black and the black a pixel further is the same black so SR on or of shouldn't do a thing there.
Who says the blackframe was even in focus to begin with

It could be though that maybe the current of the SR has something to do with it...

Current is the keyword. It wouldn't matter otherwise but it is eating some of the battery energy (well, not eating it, energy is conserved - it is converted into kinetic energy and then on into thermal energy).

On my recent holiday trip (as I started the business of plugging other threads and got a price for it I might just continue) I forgot to bring the charger and had to do with two charged batteries. So I disabled auto focus, dust removal on power on etc.
For the long night exposures it might have made a difference...

Prieni

Hi Ralf,

What I don't understand, is why you have to switch off the SR, when it is automaticly done by the camera if you use the self-timer(at any setting)

I never had the K20D but I expect the K10D/20D are working the same in that respect.

And because we are talking "dark frame" there is no focal point or reference of any kind for the SR to work with.

Could it be some sort of mechanical noise created by the shutter being kept open for a long enough time to notice?

Martin,

of course I don't have to switch SR off. It shouldn't activate SR in any case (and as far as I can see from the EXIF data it doesn't). I suspected a programmers error and the SR being still activated for the dark frame. I just did another quick check with my ear to the camera: The noise is also present in the 2 seconds before exposure.

Very strange...

Prieni