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03-02-2009, 01:33 AM   #1
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Camera temperature

Hi,

If i use exiftools to look at the data from a picture, i see in the list that the camera temparature is being displayed at the time the picture was shot.
Does anyone know where and why the camera measures temperature?

p.s where can i find a "proud k10d owner" signature?

Thanks!

03-02-2009, 02:31 AM   #2
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don't quote me on this, but i'm pretty sure the camera measures temperature so it doesn't overhead - sensors can overheat and thats generally a bad thing (as with all electronics really)... im not sure what the cutoff temperature is but i'm pretty sure the camera will shut itself down if it gets too hot internally
03-02-2009, 07:38 AM   #3
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if you dig deep enough into the technology. I think you will find that a lot of the sensor function, including but not limited to noise is a function of temperature, and the temperature recorded is the sensor, not the camera.
03-02-2009, 08:48 AM   #4
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The sensor temperature is from the camera's internal temperature

QuoteOriginally posted by Lowell Goudge Quote
if you dig deep enough into the technology. I think you will find that a lot of the sensor function, including but not limited to noise is a function of temperature, and the temperature recorded is the sensor, not the camera.
That's what most people seem to think. However, I did some experimenting and found this to be highly unlikely.

See my posting in regards to this: https://www.pentaxforums.com/forums/503932-post52.html

Or the whole thread here: https://www.pentaxforums.com/forums/post-processing-software/17353-photome-ho...if-data-4.html

03-02-2009, 09:02 AM   #5
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QuoteOriginally posted by pentaxmz Quote
That's what most people seem to think. However, I did some experimenting and found this to be highly unlikely.

See my posting in regards to this: https://www.pentaxforums.com/forums/503932-post52.html

Or the whole thread here: https://www.pentaxforums.com/forums/post-processing-software/17353-photome-ho...if-data-4.html
I think you will find that the thermal management in the camera is pretty good, BUT I am not discusssing the heating during an exposure, which I am sure pentax and all other manufacturers are managing correctly. I am discussing the difference between your camera taking a shot at -30C as opposed to +50C.

That has a big impact on gain and noise of electronic components. GPS units do the same type of thing for timing, because they are measuring microsecond differences in the time they receive time signals from satelites to calculate location. In many GPS receivers you can get the processor temperature.
03-02-2009, 11:45 AM   #6
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QuoteOriginally posted by Lowell Goudge Quote
I think you will find that the thermal management in the camera is pretty good, BUT I am not discusssing the heating during an exposure, which I am sure pentax and all other manufacturers are managing correctly. I am discussing the difference between your camera taking a shot at -30C as opposed to +50C.
Yes, I understand what you are saying.

But I was correcting what you stated about the EXIF temperature representing the CMOS sensor's actual temperature. I found no evidence to support this. In fact, later tests continued to support my original conclusion.

Believe me, a long exposure will raise the CMOS imaging sensor's temperature above the ambient temperature but the EXIF temperature recorded always showed little or no change. The only way I could achieve significantly lower or higher EXIF temperatures was by externally heating or cooling the camera.

Again, these experiments provided good evidence that the EXIF temperature is actually a measure of the camera's ambient body temperature.
03-02-2009, 01:01 PM   #7
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We would have to get the word from a Pentax engineer on where the sensor is located. However, I have had a few outside shooting sprees this winter and I found a few things out: 1) the temperature is as reported by the sensor at the beginning of the exposure, 2) the temperature will change as the camera acclimatizes until it reaches an equilibrium point. My last outside shoot was at an ambient temperature of -8 to -10C and the camera temperature was given as a steady +2C after acclimatization. Either the sensor is inaccurate (doubtful given the current state of temperature sensor tech) or it is indeed measuring something that gives off heat.

Jack
03-02-2009, 01:33 PM   #8
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This must be the third recent temperature sensor thread. I agree with Pentaxmz in that the EXIF data is the camera temperature, perhaps at the circuit board. If it was the sensor temperature it would rise during long astrophoto shoots (dozens of two minute exposures). I've checked it several times, once the camera reaches the ambient temp it stays fairly steady. In my testing it was within a few degrees C indoors and out.

I know the sensor temperature rises rapidly causing dark noise. Taking just 7 dark frames at room temperature I measured a 5:1 increase in the noise level using Images Plus software. This is why I can't do high duty cycle images in the summer (e.g. two minute exposure, no NR, 8 second save to card, repeat). I use NR plus a cool down delay between frames to prevent the sensor noise from exceeding the target nebula.

I'd love to be able to measure sensor temperature so I could make better decisions on exposure duty cycle. Even better, I'd like to control the sensor temperature like my SBIG astro camera.

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