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04-06-2014, 09:22 AM   #16
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QuoteOriginally posted by Adam Quote
Enable slow long shutter speed noise reduction and this won't happen. I recommend having it on for exposures longer than 30 seconds.
It make the process much longer, but I think if that remove these kind of noise, I will use it.

QuoteOriginally posted by maltfalc Quote
why would increased iso heat up the sensor? as far as i know, changing iso just changes how the camera interprets the signal from the sensor. if anything, with long exposures a higher iso should mean less heat because of the shorter exposure.
+1

04-06-2014, 12:56 PM   #17
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QuoteOriginally posted by mtux Quote
It make the process much longer, but I think if that remove these kind of noise, I will use it.
Indeed, the wait can be very annoying, but it does pay off since you're already spending a lot of time getting the exposure right in the first place. One solution would be to have 2 or more bodies in use at a time.

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04-06-2014, 03:38 PM   #18
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QuoteOriginally posted by maltfalc Quote
why would increased iso heat up the sensor? as far as i know, changing iso just changes how the camera interprets the signal from the sensor. if anything, with long exposures a higher iso should mean less heat because of the shorter exposure.
To my understanding the signal of the sensor gets amplified to achieve the higher sensitivity. Amplifying means more current which generates more heat due to higher resistance. Long exposures (I`m still talking about those) leave the shutter open for extended periodes of time, way longer than normal shooting.
04-06-2014, 11:28 PM   #19
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QuoteOriginally posted by TenZ.NL Quote
To my understanding the signal of the sensor gets amplified to achieve the higher sensitivity. Amplifying means more current which generates more heat due to higher resistance. Long exposures (I`m still talking about those) leave the shutter open for extended periodes of time, way longer than normal shooting.
the signal gets amplified, but the reason it's being amplified is to compensate for the original signal being weaker due to the shorter exposures at higher iso settings. a 10 second exposure at 100 iso and a 5 second exposure amplified to 200 iso should have roughly the same final signal strength and therefore generate roughly the same amount of heat, plus or minus any difference in efficiency of the amplifier at different isos. at 200 iso the noise will also be amplified along with the signal, so that will add some additional heat, but the exposure will be half as long, so any heat generated during the exposure will be halved, more or less. probably.

04-07-2014, 03:23 AM   #20
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Why don't you just post the original image?

Thanks
04-07-2014, 06:43 PM   #21
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QuoteOriginally posted by Steve.Ledger Quote
Why don't you just post the original image?
Why then?
You can see these pixels only in 100% crop because they are about 1/16000000000 of the image, and you can't see that in a normal screen resolution.

But I will post the photo once I got time to PP it or the other one from the exact same view but @ 30sec exposure.
04-07-2014, 07:05 PM   #22
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Well if you want forum members to help out you have to help us.
Simples.

But we don't need a PP version, the ORIGINAL please
04-07-2014, 07:53 PM   #23
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QuoteOriginally posted by Steve.Ledger Quote
Well if you want forum members to help out you have to help us.
But I already got my answer, thanks for helping.

04-07-2014, 09:50 PM   #24
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QuoteOriginally posted by maltfalc Quote
a 10 second exposure at 100 iso and a 5 second exposure amplified to 200 iso should have roughly the same final signal strength and therefore generate roughly the same amount of heat
There is a bias voltage applied to the photosensitive circuitry and fluctuations from that bias voltage is the signal, not the absolute voltage. Because of that, there is always current flowing through that circuitry, which generates heat. As the sensor gets hotter, its electrical characteristics change, and those changes aren't perfectly uniform, which results in "false" readings at various photosites. Like any noise or dust, if it is consistent from one "exposure" to the next, it can be digitally removed from the final image.
04-08-2014, 01:17 AM   #25
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QuoteOriginally posted by RGlasel Quote
There is a bias voltage applied to the photosensitive circuitry and fluctuations from that bias voltage is the signal, not the absolute voltage. Because of that, there is always current flowing through that circuitry, which generates heat. As the sensor gets hotter, its electrical characteristics change, and those changes aren't perfectly uniform, which results in "false" readings at various photosites. Like any noise or dust, if it is consistent from one "exposure" to the next, it can be digitally removed from the final image.
Rglasel, you explained this way better than I ever could in my limited technical English, thanks
04-08-2014, 11:55 AM   #26
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QuoteOriginally posted by RGlasel Quote
There is a bias voltage applied to the photosensitive circuitry and fluctuations from that bias voltage is the signal, not the absolute voltage. Because of that, there is always current flowing through that circuitry, which generates heat.
ah. good to know. does the bias voltage differ from one iso setting to another?

Last edited by maltfalc; 04-08-2014 at 12:03 PM.
04-08-2014, 11:12 PM   #27
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QuoteOriginally posted by maltfalc Quote
does the bias voltage differ from one iso setting to another?
I don't design sensors so I don't really know for sure, but any relationship between bias voltage and ISO setting has to be indirect. The ISO setting is the amount of gain applied to the signal, in essence how much the signal is amplified after being detected. The problem is that any noise will be amplified by the same amount, unless steps are taken to electronically reduce the noise relative to the signal. As the spacing between electrical paths in the sensor gets smaller, the sensor becomes more susceptible to noise as well, and the quantum efficiency of the photosites on the sensor will vary somewhat as the intensity of light energy hitting them varies. To extract greater dynamic range in the final signal produced by the sensor, two factors can be controlled electronically, the bias voltage and the sampling interval, and I'm sure that the designers of the current crop of super-sensitive sensors have built in ways to adjust both of those factors.
04-13-2014, 03:03 PM   #28
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QuoteOriginally posted by severalsnakes Quote
You might look into "hot" pixels. As I understand it, "hot pixels" are basically just blown out pixels that can show up during long exposures and/or high ISOs? I had a bunch crop up during a trip to the zoo when I took a lot of pictures in very very low light in some nocturnal exhibits. They are not permanently damaged pixels and they "reset" themselves after a short period of time. I am no technical expert (obviously), but you mentioned it was a long exposure, so this could be the same "hot pixel" problem.
Yes! There is pixel mapping in the menu but I haven't tried it
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