Photo: ~jjjohn~

Why High Humidity is bad for your equipment

Fungus grows in between lens elements and under the lens coatings. Once it gets started, it is a pain to get rid of, and causes soft spots in your photographs, being the equivalent of having a fingerprint on your lens.

Fungus or Mould thrive in dark, humid places where there is little, or no movement of air (sound familiar? look at where you store your camera equipment). Very often camera equipment ends up in drawers, cupboards, or basements; all of which are dubious places to store them. Do not keep cameras as they need to be exposed to light and fresh air from time to time. A camera or lens will last through the years if it is stored correctly

Lenses and camera equipment are stored at a optimal relative humidity (RH) level of around 35% to 45%. A good rule of thumb to figure the optimal RH to store your equipment at, is to look at it’s optimal operating humidity range, and half it. For example, the Canon EOS 5D’s operating humidity range is 85% RH or lower, so a good indicative range to store it would be between 35 and 45% RH.

Humidity Range – Why Low Humidity is bad for your equipment

Remember, that you could also run into problems from keeping your RH levels too low. All camera lenses and bodies have a number of moving parts – gears, sliding thingies, and rolling thingies – and they’re all lubricated with a light machine oil. Keeping your RH too low could dry up that oil quicker than usual, making these parts wear out sooner, and work sluggishly. I also think that the rubber on the camera tends to harden quicker in dry air.

There also seems to be another kind of mould that affects camera equipment at very low RH levels; I’ve only come across this in one place, so I don’t have much info on that. If you have some information that you could add, please do leave it in the comments.

Photo: dawn_perry


So what’s the solution? The cheapest option is to use your camera as frequently as possible; The exposure to light, especially UV light kills the fungus. While this is not a problem for active enthusiasts, those who store their cameras for any length of time need an alternative.

Alternative 1 – Sunlight / UV Radiation

Put your camera out in the sun from time to time. Remove the lens (or you could end up with a hole burnt in your shutter or some other part), filter, body, etc, and put them all out in sunlight for a while. If you manage to work this into your monthly camera care routine, you should be fine.

You could also try what some photographers do: use a UV lamp in their storage area. Why? Because prolonged exposure to UV (Ultra-Violet) radiation kills or retards fungal growth. Do remember to take your UV filters off if you decide to try this method out, because they are designed to keep UV rays out of your lenses. The lens coating blocks UV light too, to an extent.

Ok, so you’re exposing it to light on a regular basis, but what if you live in a region that is perpetually humid? See alternative 2 for an answer.

Alternative 2 – Dessicants

As always, there are the cheap options, and the expensive options. In either case, you’ll most likely need a Hygrometer so that you know what the relative humidity is, at any given time.

Cheap Option – Silica Gel

Silica-Gel is the cheap way out. It is a dessicant (something that de-humidifies the air in the vicinity of your camera equipment).

You can buy Silica Gel either as crystals, or sometimes as tiny spheres. Most often you find them in porous sachets so that they don’t disperse among your equipment. If you decide to go with Silica Gel for your cabinet, remember that you should get the indicative variety
. They are blue when they’re fully absorbent, white-ish when they’re partially full of moisture, and pink when they’re fully saturated. You can “Re-charge” your Silica Gel at this point.

You’ll need a container like the Dry Storage Silica Gel Dehumidifier to store it, yet create enough air-flow through the crystals. You’ll also generally need lots of silica gel. But remember that it lasts a long time, and needs no further investment.

Remember, that keeping saturated silica-gel in your camera storage could do you more harm than good by actually releasing more moisture into your storage.

Expensive Option – DeHumidifiers

As with everything, there has always got to be an expensive option. De-Humidifiersusually use mechanical means to reduce the relative humidity of the air around it. De-Humidifiers are usually quite effective, and can reduce the time you spend on modifying your camera’s environment, but they generally draw significant amounts of electricity.

You could also use your Air Conditioner to reduce the ambient humidity to a safe level for your camera equipment. This is because Air Conditioners dehumidify as they chill the air, leaving a comfortable storage humidity for lenses and cameras.

Photo: Matthew Fang


To wrap up, remember that the best maintenance/fungus prevention plan for your camera involves your regular use of the equipment. Regular use keeps the lenses and camera body aerated and exposed to sunlight, thus killing fungus.

If you dont use your camera often, make sure that it is stored in a well ventilated area with an ambient humidity range of 35%-45% RH. Also remember to take it out often and expose it to sunlight.

If you live in a humid part of the world, you could try one of the other two options mentioned above: Chemical Dessicants or De-Humidifiers.

If you have had experience with fungus and humidity affecting your camera equipment, and have found an alternate solution to those mentioned above, please do leave a comment so that our readers may benefit from your experience.



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by  on OCTOBER 19, 2008