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I'm searching for camera modules using CMOS image sensor. But I found something interesting. Some vendors specified operation humidity between 20~80%. But does it make sense that low humidity affect to camera? Could anyone please explain what happens when you put camera in such environment?

Here are examples

  1. http://astronomy-imaging-camera.com/products/usb-3-0/asi224mc/#comment-4142
  2. https://www.leopardimaging.com/uploads/LI-USB30-M021X_datasheet.pdf
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  • \$\begingroup\$ You may also find that manufacturers are unable, unwilling or indifferent to testing at relative humidity levels below those that occur in common use. You may find that the devices will work fine at 0%. With optics you may find static induced dust more common with HV devices I believe corona discharge may be more likely. Lots of equipment is shipped with desiccants and could be close to 0% and will work right out of the box. Excessive caution or copying of legacy specifications is likely to be the real reason. \$\endgroup\$ – KalleMP Sep 4 '15 at 20:16
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It's not specific to cameras that low humidity causes problems: -

Too low humidity may make materials brittle

Also this: -

a very low humidity level favors the build-up of static electricity, which may result in spontaneous shutdown of computers when discharges occur

This is stated on this wiki page and I read "computers" as any non-trivial electronic circuit.

The full paragraph is: -

Many electronic devices have humidity specifications, for example, 5% to 45%. At the top end of the range, moisture may increase the conductivity of permeable insulators leading to malfunction. Too low humidity may make materials brittle. A particular danger to electronic items, regardless of the stated operating humidity range, is condensation. When an electronic item is moved from a cold place (e.g. garage, car, shed, an air conditioned space in the tropics) to a warm humid place (house, outside tropics), condensation may coat circuit boards and other insulators, leading to short circuit inside the equipment. Such short circuits may cause substantial permanent damage if the equipment is powered on before the condensation has evaporated. A similar condensation effect can often be observed when a person wearing glasses comes in from the cold (i.e. the glasses become foggy).[23] It is advisable to allow electronic equipment to acclimatise for several hours, after being brought in from the cold, before powering on. Some electronic devices can detect such a change and indicate, when plugged in and usually with a small droplet symbol, that they cannot be used until the risk from condensation has passed. In situations where time is critical, increasing air flow through the device's internals, such as removing the side panel from a PC case and directing a fan to blow into the case, will reduce significantly the time needed to acclimatise to the new environment.

In contrast, a very low humidity level favors the build-up of static electricity, which may result in spontaneous shutdown of computers when discharges occur. Apart from spurious erratic function, electrostatic discharges can cause dielectric breakdown in solid state devices, resulting in irreversible damage. Data centers often monitor relative humidity levels for these reasons.

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