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05-30-2014, 07:35 PM   #1
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No luck trying to capture star trails

Using the wireless remote:

For some reason, both of my Lithium priority batteries get completely drained when I open the shutter for a long time. The first time on a fully charged battery I opened and closed the shutter for 45 minutes - after the camera closed the shutter it couldn't be turned on. I believe there wasn't even enough power to save the image.

So I put in my Wasabi batttery that was fully charged and took a 15 minute exposure. The exact same thing happened. No image recorded and camera battery dead.

Is this normal ?


Last edited by Michael Piziak; 05-30-2014 at 07:40 PM.
05-30-2014, 07:40 PM   #2
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QuoteOriginally posted by Michael Piziak Quote
For some reason, both of my Lithium priority batteries get completely drained when I open the shutter for a long time. The first time on a fully charged battery I opened and closed the shutter for 45 minutes - after the camera closed the shutter it couldn't be turned on. I believe there wasn't even enough power to save the image.
Was slow shutter speed noise reduction on? That would lock the camera up for an additional 45 minutes.

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05-30-2014, 07:41 PM   #3
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Which camera? Some of them have "dark frame subtraction" which can't be turned off for long exposures -- it is a noise reduction technique that involves taking a black image for the exact same time as the shutter was open. In other words, 15 minute exposure, you then have to wait another 15 minutes for the camera to process during which time it can appear dead but actually is not. But if your battery was truly dead?
05-30-2014, 07:43 PM   #4
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QuoteOriginally posted by Adam Quote
Was slow shutter speed noise reduction on? That would lock the camera up for an additional 45 minutes.
Not to my knowledge. Actually, I don't know what that is or if I should have used that.

---------- Post added 05-30-14 at 07:44 PM ----------

QuoteOriginally posted by vonBaloney Quote
Which camera? Some of them have "dark frame subtraction" which can't be turned off for long exposures -- it is a noise reduction technique that involves taking a black image for the exact same time as the shutter was open. In other words, 15 minute exposure, you then have to wait another 15 minutes for the camera to process during which time it can appear dead but actually is not. But if your battery was truly dead?
Pentax k-r is my camera.

So you think the battery wasn't dead, and I prematurely fiddled with it by turning the camera on and off and switching the batteries, etc.... This may make sense since the only thing the camera would do is close the shutter when I pushed the wireless remote button after X minutes.

05-30-2014, 07:56 PM   #5
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QuoteOriginally posted by Michael Piziak Quote
Not to my knowledge. Actually, I don't know what that is or if I should have used that.

---------- Post added 05-30-14 at 07:44 PM ----------



Pentax k-r is my camera.

So you think the battery wasn't dead, and I prematurely fiddled with it by turning the camera on and off and switching the batteries, etc.... This may make sense since the only thing the camera would do is close the shutter when I pushed the wireless remote button after X minutes.
Try one for a shorter time but at least 30 seconds, and then see if it stays asleep a time equal to the exposure time. That's dark frame subtraction. It can be turned off on the newer models (and will be called something like "slow shutter NR" as Adam pointed out) but on some of the older models could never be turned off. Don't know about the K-r... (Of course you may want to leave it on -- it does WORK. Google it to find out how.)
05-30-2014, 09:29 PM   #6
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QuoteOriginally posted by Michael Piziak Quote
Not to my knowledge. Actually, I don't know what that is or if I should have used that.
It's on by default, so it was probably the culprit. You can disable it in the second tab of the record menu.

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05-31-2014, 07:47 AM   #7
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I tested it and yes it does take several minutes after a long exposure to process the image.

Is the slow shutter speed noise reduction what it is processing for so long ?
05-31-2014, 08:00 AM   #8
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QuoteOriginally posted by Michael Piziak Quote
I tested it and yes it does take several minutes after a long exposure to process the image.

Is the slow shutter speed noise reduction what it is processing for so long ?
It is actually taking another image of nothing/black (the sensor is active, but the shutter stays closed) for the same amount of time as the actual picture. This gives it a picture of "noise only" that the sensor produces under the same conditions as the actual exposure. So then using that, it attempts to "subtract" that noise from the original. It is a technique you can actually do yourself in photoshop by taking your own black/noise picture. Google "dark frame subtraction" for more detailed info...

05-31-2014, 07:01 PM   #9
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One thing I wonder about. After a long exposure and I close the shutter, I put my ear up to the camera and sounds like an electrical sizzling sound. Is there a tiny man in there frying bacon ?
05-31-2014, 07:48 PM   #10
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QuoteOriginally posted by Michael Piziak Quote
One thing I wonder about. After a long exposure and I close the shutter, I put my ear up to the camera and sounds like an electrical sizzling sound. Is there a tiny man in there frying bacon ?
Yes. Yes there is. So totally normal.
06-01-2014, 07:04 AM   #11
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QuoteOriginally posted by vonBaloney Quote
Yes. Yes there is. So totally normal.
One will never hear that noise unless they put their ear up to the camera. I'm glad it's normal though.
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