[tnis0612]

I assume that if my batteries die with the shutter open I wont get an image. Is that correct?

I'm curious as to how long a fresh set of Eneloops will last in the k-x during one long exposure. Does anybody have any experience with this? I'll be out camping and want to try some star trails and wont have the ability to plug in. Thanks!

[mickeyobe]

I assume that if my batteries die with the shutter open I wont get an image. Is that correct?

I'm curious as to how long a fresh set of Eneloops will last in the k-x during one long exposure. Does anybody have any experience with this? I'll be out camping and want to try some star trails and wont have the ability to plug in. Thanks!

I wish I had facts and figures but I don't.
I do know that long exposures do severely drain the batteries.
When, unsuccessfully, trying to capture lightning flashes I stacked neutral density filters and a polarizer to make exposures as long as six minutes but the batteries still retained some charge.

I should think you will need power to record the image as it is not an instantaneous procedure with long exposures and continues for a while after the shutter is closed.

Why don't you put your camera to the test. Leave the shutter open until the fully charged batteries die and time it. Bear in mind that shorter long exposures will allow the batteries to bounce back a little so you will get longer total use from them with repeated long exposures of shorter duration.

If you do make such a test please let us know the results.

Mickey

[Adam]

That would be a very interesting test, but would something like that have a potential to damage the sensor? It isn't exactly designed for hours of exposure, AFAIK.

[Eruditass]

Also, higher new mAH might actually be better than LSD in this case (depends on the cutoff voltage for the K-x and the particular battery). Well, it depends on how long it will take you to get out there and take the picture. Then there's lithiums.

[TOUGEFC]

Not Eneloops but .... on my first attempt of star trails last month on my k200d,
i had a set of energizer lithiums in camera, already taken several hundred photos, then did 2 captures of star trails both around 15mins exposure plus the 15min dark frame after them both and batterys were still fine for another several hundred photo's.

[Ben_Edict]

That would be a very interesting test, but would something like that have a potential to damage the sensor? It isn't exactly designed for hours of exposure, AFAIK.

These sensors are really robust and won't be damaged. The only problem is, that the electronics gets warmer and will produce much more thermal noise, which is more or less absent in standard exposures.

I am not sure how the K-x works. But for long expsoures with the K20, the battery power will be required to take the subsequent darkframe and processing and then for the final write to memory card. If the darkframe substraction cannot be switched off in the K-x it will work like a second expsoure of similar length to the primary one.

I would think about making an external power pack, that could be connected via the external DC-power jack of the camera (if the K-x has that).

Ben

[Just1MoreDave]

I would use non-rechargeable lithium AAs for this, just as extra insurance. As you say, if the batteries run out, you get nothing. Lithiums should last longer.