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A question was asked on what would happen to a camera if stored in a low humidity environment. mattdm's answer was:

In a word, static.

Digital cameras are electronic devices, and they also have moving parts, both plastic and metal. This is a great combination for build-up of static charge and for sparks to fly.

These sparks — even very, very tiny ones — can cause malfunction of the electronics or even permanent damage.

My question is this:

Are there ways to prevent this static buildup/discharge when using a camera in low humidity?

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+1 I am also interested to know too. From what I know, there is a certain RH value that will be balance (or just nice) that it will stop mold and static - which is 40% to 50%. So, I was wondering beside setting such RH value, are there other simple way to prevent static buildup/discharge. Would wearing a Antistatic wrist strap when using a camera in low humidity help? –  Jack May 11 '12 at 5:22

1 Answer 1

up vote 4 down vote accepted

Are there ways to prevent this static buildup/discharge when using a camera in low humidity?

Dons electrical engineer's day-job hat:

Summary:

  • Not usually an issue.
    Means can be provided to equalise person-equipment or person-ground voltages if felt necessary..

  • If required - the ground of the internal electronics is almost certainly connected to the tripod screw mount on the base of the camera and probably also to the metal strap mounting lugs. Touching any of these points or metal connected to them will almost certainly equalise camera and body voltages without causing any problems.

    (If an ohm-meter check between lugs and base screw shows a low resistance connection then it will be camera "ground". )

  • Modern electronic equipment should be designed to resist such problems. If not, ask why.

The most common principal risk to electronic equipment from ESD (electrostatic discharge) is discharge of energy accumulated as electric charge in the capacitor that the human body forms with ground. The ways to best deal with this are

  • Robust equipment

  • Prevent charge buildup on body

  • Keep body at same voltage as equipment

  • Equalise voltages on body and equipment gradually

  • Discharge body to ground.

All reputable modern electronic equipment is required to be ESD proof with the ability to receive spark discharge from a human body model without damage and usually without malfunction. Equipment which fails to achieve this in most cases is not suitable for the purpose for which it is sold and may be able to be dealt with under consumer gauarntee legislation. But ...

Charge buildup is frequently caused by rubbing of "suitable" materials together. While I could go into a list of materials and characterisics, most people are aware enough of what causes this effect. Polystyrene, silk, certain other fabrics, non conductive material ... . If in dry conditions yopu can rub material X onm material Y and then either X or Y will make hair on person Z's head stand on end "we have a problem". Because of the inconvenience prevention is not usually a main method of attack.

If equipment and user are in conductive contact then voltage swill be equalised and will remain so if the body is raised to a high voltage. Discharge of the body to ground via the equipment could be an unlucky problem. If user and camera are inbody to metal contac voltage will be low. If not, touching an external large metal portion initially will equalise voltages and will usually not cause problems

In problem areas user voltage to ground can be zeroed by use of 'heel grounders' in shoes which maintain electrical contact with user and ground when shoes are non conductive. his is common in eg manufacturing facilities but rare for photographers.

In extreme cases where local circumstances cause known problems a slow discharge path can be provided which limits energy transfer rate./ Slow is relative. A 1 megohm to 10 megohm resistor is commonly used. Where needed this could be either mounted on the camera as a stud or extrusion with the user touching it first, it could be built into a case stud or similarly incorporated or a conductive mesh or simi;ar of high resistance could be integrated into the equipment. In a gear box or bag a butyl rubber sheet will usually provide high but usefuil discharge path. Some Butyl rubber may be too conductive.

In a check of 3 DSLRs here (2 x Minolta, 1 x Sony) all had a low resistance path between tripod mount screw metal and the strap mounting lugs. This will be almost certainly the case with a metal frame camera and still probably true in a camera with minimal metal internally as the manufacturer needs to be able to deal optimally with ESD and having electrically floating metal parts intruding into the system would be unwise.

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Wow! Thanks for the detailed answer! => –  Lynda May 11 '12 at 18:38

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