Lens gets very hot - design flaw or clever feature?

H-R

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Although I have been using ITB-100HD and ITB-100SPW dashcams for several years without any issues, I have never noticed this.

During some recent testing of various memory cards with constant recordings of upto 48+ hours inside my home (ambient temp. around 20 degrees C) I have noticed by accident how hot the lens had become - in fact so hot that it was borderline to keep touching it (which suggest over 60 degrees C).

The rest of the case was only handwarm (maybe mid 30s Celsius), and the SD card felt a bit warmer still, but not really hot.

Admittedly, one would normally not have continuous recordings run for that long, but I noticed similar temperatures also with much shorter times, like when in parking mode for say 3-4 hours.

This made me wonder why just the lens would be so hot? I can't see how a CMOS sensor would draw much current to explain this. So here I am speculating that it might actually be some clever design idea whereby most of the internal heat is transported to the outside of the enclosure via the lens, which might be in tight mechanical contact with some heat producing internal electronic circuits?

The Itronics dashcams are renowned for their high temperature rating up to 70 degrees Celsius. Could it be that the lens is used as some sort of clever heatsink?
 

Harsh

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So here I am speculating that it might actually be some clever design idea whereby most of the internal heat is transported to the outside of the enclosure via the lens, which might be in tight mechanical contact with some heat producing internal electronic circuits?

The Itronics dashcams are renowned for their high temperature rating up to 70 degrees Celsius. Could it be that the lens is used as some sort of clever heatsink?
If there was a way, manufacturers would ideally want none of the heat going to the lens holder/mount. The heat can cause expansion and warping of the plastic holders/mounts, which results in out of focus or focus shift issues (temporary or permanent). Metal holders/mounts handle the heat better, in extreme cases if there is a shift or OOF problem, it'll go away after a cool down. Fibre reinforced plastic (FRP) mounts are more resistant than the regular ones.
 

TonyM

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I noticed this morning with a misted up windscreen that my dashcam generates enough heat to de-fog its own lens and also some of the windscreen around it - so there is a benefit to having a hot lens!
 
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H-R

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CMOS sensors generate a lot of heat
Thanks for pointing this out, I was completely oblivious to this fact. One just never stops learning. Further research now confirms that this is indeed quite an issue, even with digital photo cameras when they run for longer times in HD movie recording mode.

Me thinking that CMOS devices are very low power devices which don't produce much heat, but coming to think of it, there are 2 Million pixels in the ITB-100 (much more in higher specced resolution dashcams), each pixel constantly driving one or more transistors between on/off states, for several hours non-stop, and that on a very tiny surface.

Viewed in this context it makes sense that image sensors can get that hot, because even very tiny currents in the region of nanoamperes multiplied by 2 Million quickly add up to become a heat source.

Makes me even more admire how Itronics manages to specify an operating temperature range of up to 70 degrees C. Clearly the used material for the lens must be very heat resistant, as I never noticed distortions or out-of-focus issues, even when the dashcam was running in a very hot car.
 

jokiin

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Too many ¯\_(ツ)_/¯
they also avoid a lot of heat by running lower bitrate so they trade off some image quality performance to be able to run at higher temps, most cameras are fine up to 70°c but that's about the practical limit of the hardware currently, we have been looking at a new sensor which is stable up to 100°c but the rest of the hardware isn't quite there yet anyway
 

kamkar1

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:eek: need to plumb that sucker with some cobber pipe and some fittings, and hey presto you have a espresso maker too :D

Would be popular with the female motorists, not only can they put on makeup on the way to work, then they can allso have some coffee, and record it all what it go all wrong :p
 
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