Does humidity affect focusing?

[laatsaheeb]

I have had my Canon Digital Rebel for about two weeks now. Today all of a

sudden I am noticing extremely slow focusing with both my lenses (50mm/1.8 and

70-300 IS USM).

Today is the first day where its really humid since I got my camera. Could the

slow focusing be due to the humidity? I am thinking there might be some

condensation build up in the camera since the camera was in the car with A/C

on right before I took it outside and notice the problem.

 

THank you,

-uday

[John Crowe]

Look for the condensation on the outermost lens elements as fogging. Yes this will affect autofocus. The humidity will likely do nothing to the electronics or motors themselves it is the fogged glass which will make the focus search.

 

 

If this is the case you will have to give the lenses a few minutes to acclimate as you take them from one extreme to the other. You can help protect the lenses by putting them in airtight bags/containers until they do arrive at the environment temperature. Air conditioning to exterior is not likely as severe as winter temps into indoor swimming pools but similar effect.

 

 

With super telephoto lenses the haze in the atmosphere may be affecting focus ability as well. Good luck.

[laatsaheeb]

Thank you John for your response but I am wondering doesnt condensation also build up on the CCD sensor?

[neild]

I'd really hope not - besides, there's more things that can go wrong inside and electronic camera than just bad focusing when there's moisture forming, like the whole thing getting fried!

[John Crowe]

Use the glass as a guide. If there is no condensation on the glass then there is not likely any condensation in the body. The outside elements of the glass are far more prone to condensation than the sensor.

 

 

In any case you have to avoid the big temperature swings. Keep the equipment in your camera bags and in the trunk so they are as close to ambient temperature as possible. At least when it is hot out you don't have to worry about separating batteries from cameras.

 

 

As far as frying electronics go I would be more concerned if the moisture happened to contain salt from a nearby ocean. A drop of water from a sidewalk with road salt on it got into my camera once and fried the main board. I've been caught in rainstorms without any problems.