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03-21-2010, 01:47 AM   #1
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k200 Battery life when doing star trails

Anybody here have experience of how long a set of fully charged Enerloops in a K200 on bulb should last?
The air is starting to cool and become clear in these parts so I hope to get some more startrail shots.

Cheers

g.

03-21-2010, 11:37 AM   #2
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QuoteOriginally posted by GrahamD Quote
Anybody here have experience of how long a set of fully charged Enerloops in a K200 on bulb should last?
The air is starting to cool and become clear in these parts so I hope to get some more startrail shots.

Cheers

g.
in my country it works around 500 shots ( 3hrs before it fully depleted ) powerex ranks second ... but some sez that it also depends on the temperature of the surroundings
03-21-2010, 04:32 PM   #3
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It seems the drain rate on batteries goes up dramatically the longer the shutter is open. With low-self-discharge NiMH batteries, you can probably get a 30 minute exposure without too much trouble. Remember that there's a second 30 minute dark frame exposure immediately afterward, so a 30 minute exposure is really a 60 minute one. That's a long time for the shutter to be open. Unfortnuately, if the batteries die during the dark frame, you probably won't realize it anyways and then you'll wonder why your camera is dead.

(I assume the K200D does dark-frame subtraction like all current CMOS sensor-based Pentax cameras)
03-22-2010, 02:50 AM   #4
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QuoteOriginally posted by GoremanX Quote
It seems the drain rate on batteries goes up dramatically the longer the shutter is open. With low-self-discharge NiMH batteries, you can probably get a 30 minute exposure without too much trouble. Remember that there's a second 30 minute dark frame exposure immediately afterward, so a 30 minute exposure is really a 60 minute one. That's a long time for the shutter to be open. Unfortnuately, if the batteries die during the dark frame, you probably won't realize it anyways and then you'll wonder why your camera is dead.

(I assume the K200D does dark-frame subtraction like all current CMOS sensor-based Pentax cameras)
Yes the K200 does the dark frame substraction (but I turn it off). When I last went out the batterys dropped 1 minute short of a 12 minute shot!, the batteries already had some use.
Spare set was on hand and a car came from nowhere and flared the whole scene on the second attempt!
Started to get cold so went back to the hotel.

03-22-2010, 03:51 AM   #5
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QuoteOriginally posted by GrahamD Quote
Yes the K200 does the dark frame substraction (but I turn it off). When I last went out the batterys dropped 1 minute short of a 12 minute shot!, the batteries already had some use.
Spare set was on hand and a car came from nowhere and flared the whole scene on the second attempt!
Started to get cold so went back to the hotel.
Lucky, the K20D, K7 and K-x can't disable dark frame subtraction. It's a great detriment to astrophotography.
03-22-2010, 04:14 AM   #6
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Interesting, im going to have a go with my k200d to do star trails soon, will turning off the dark frame substraction have much of an impact on the photos?
03-22-2010, 04:28 AM   #7
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QuoteOriginally posted by TOUGEFC Quote
Interesting, im going to have a go with my k200d to do star trails soon, will turning off the dark frame substraction have much of an impact on the photos?
You can do your own dark frame subtraction in post processing. Just take a dark frame (a long exposure, say 5 to 20 minutes with the lens cap and viewfinder cover on) and save it, then you can use it to subtract noise and bright pixels from your long exposure shots. The best thing to do is have a dark frame for 1 minute, 5 minutes, 10 minutes, 20 minutes and 30 minutes and just use whichever one is closest to the actual exposure time you took to remove the noise. There are many software solutions that will do dark frame subtraction for you. I use UFraw, but that's a RAW conversion software. It won't work with JPGs there. I'm sure there's probably a Photoshop technique or filter to do it.
03-22-2010, 05:03 AM   #8
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Ok thanks, i dont shoot jpeg, RAW only. Can lightroom do a dark frame subtraction?

03-22-2010, 06:56 AM   #9
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no idea, I don't use Lightroom. Hopefully someone else who does can enlighten us both.
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