K10 exposure query

Hi all,
Does anyone know what is the longest shutter time that can be used. I'm pondering using tens of minutes rather than seconds in very poor light conditions.
I have noticed that it seems to take ages for the "save" or at least the "display preview" to be available after a long exposure, which makes me wonder why

regards
Bernard

There is no set limit if you use B mode. This can be via remote control (cable or wireless) to save you having to keep your finger on the button all the time.

The camera is delayed - for the length of the exposure again - while it performs special Noise Reduction. This is an option for long exposures on the K10D.

Actually as the shutter uses current to keep open, there is a limit to the B setting - the amount of battery charge that is possible and how long that will sustain an exposure for.

For film cameras using Lithium batteries this is probably 10 hours or so, but I've never seen a figure for DSLRs. I would imagine after a few hours the sensor would get quite hot and noisy.

Check this thread out.

https://www.pentaxuser.com/forum/topic/k20d-post-shoot-processing-times----15488

A mains adapter could be used for extremely long exposures, though I would indeed be worried about the sensor over-heating before a battery ran out.

Other solution would be to make several exposures and overlap them together to create a longer one.
here are some links link link link

Thanks all,
I'll carry on experimenting.
I had been rather concerned about the delay time after closing the shutter might have been due to some damage that I had done by leaving the shutter open too long.
Incidentally The longest has been about 25 minutes so far. I was trying to capture street scenes at night with just soft incident light.

To Anvh - I haven't even got round to trying out your thoughts yet. A friend has suggested I use multiple images (per page 166 of the manual) but I can't see how I gain as the images are consolodated in the camera (I think).
Your links seem to suggest adding the images externally (photoshop or the like, but how do I tell what I've got at the time of exposure as the display will be quite dark.

As I said I'll carry on experimenting

thanks again
Bernard

First of all the first link this one link is wrong in his basics.
It explains how to make the standard HDR exposure. It's in some way the same but different.

With HDR we take a photo of the low, mid and high lights and then combine them in one shot so that the captured range of the photo is increased.

With stacking we do something else, to explain it very simple we add all the exposures together so simply speaking 2 exposures of 30 seconds will give you an exposure of equivalent of 60 seconds and also reduce noise in the mean time.

What you refer to at page 166 is what is usefully for HDR photos.

Yes you basicly only know what you got when you've progressed it at home but you can do more with the photos in photoshop and less likely to come home with a ruined shot.
If you ruined a shot of 25 minute then that would be worse then loosing on of the 30 seconds shots.
Also you don't need to do dark frame with stacking, noise will get removed because you use multiple shots and noise is never always the same.

This the best site that explain it link