30% is too dry for rubber, it will eventually destroy the elastic of rubber, not sure ur wonderful drybox has auto re-moist the box, else, open close the box few times to let wet air in.

45% is your targeting RH.

good question. unlike those boxing, they are dry in the first place. and during packaging, i believe their factory is very clean. and shop is wipe everyday. no leather or wet cushion or "bed" nearby to store fungus spore...

then why does our lens is prompt to fungus? because we took it outdoor, humid area, dust, zoom in and out, sometimes, got rain on, or during rainy days, room RHumid can reach 90+, and there is a lot fungus spore in the house, especially your room, ur bed has like 98% fungus spore.

Drybox has many type, analog or semi digital or full digital.

analog uses a, well analog reader, and fader switch for u to control how powerful the drying process, which u have to check now and then for the right RelativeHumid %~

semi analog uses a digital reader, more accurate, but still, a fader switch where u need to adjust if its too dry.

full digital, well, automatic stops when desire RH reached. and runs again when its wet(opened). best thing bout full auto digital is, if its TOO DRY, it has ways to make it back to wet again

eg: accidentally hit 40%RH when ur setting is at 45%, it will let its "iced" melt back to wet back the drybox.

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Added on September 2, 2011, 6:58 pmso, its running full time, power consumed? about less then rm3 electric bill each month... cheap