inside of camera fogging, even when climate acclimated

[KellyLynne1968]

hello!! I have a Canon 7D, and typically use my sigma 24-70 lens on it.  I moved to NC from MI six years ago, and I do a ton of beach shoots. This time of year, same thing...i put my camera in my car overnight before a shoot, make sure no AC, typically get to the shoot early and set the camera outside next to me for a half hour. Should be good right? NOPE. Getting low to the sand is like putting my camera over a pot of boiling water steam. instantly fogs up on the inside and out. Yesterday, i was standing doing a family shoot. started out okay, I could tell by zooming in on the images that the skin was a bit grainy from the moisture in the air. Then half way through the shoot, camera was totally fogged up on the inside, even more than the outside of my lens. Humidity was 80 percent yesterday and this coastal area of NC often gets "waves" of high humidity and ocean mist that the camera only tends to pick up. But nothing subsided the inner fogging of my camera, until i walked back up to the parking lot. This happens every summer and quite honestly, this never happened in Michigan and im about fed up with it, lol. any advice?

[KellyLynne1968]

Well if it was 'saltwater' I would think my lens would have died a long time ago as this has been happening every summer lol. It's a mystery. Just going to try what my camera repair guy said and try a prime instead of a zoom down there and see what happens. Incidentally, after the beach shoot was done they wanted some shots in front of the beach house... concrete... inside digging cleared up for that.

[Waddizzle]

Does this happen with other lenses, too?

A lens, or a camera body, that seems to full of moisture is probably a prime candidate to develop mold and mildew.

[KellyLynne1968]

exactly that is what scares me, im going to have it looked at today.

[KellyLynne1968]

Ya I always have silica packets in my bag.well I made the two hour drive to the camera shop today. Sure enough the moisture is getting in through the lens where it attaches to zoom. I've been told to put it in an air tight container for a week with the silica packages . He said most likely it will happen again because the lens does not have weather seal. Said if I concentrate on not zooming and using it more like a prime that may help. I really love my sigma lenses. I only have one L series lens that I use for weddings . Guess I should have invested a longggg time ago in weather sealed lenses? Now that I'm close to retiring lol

[TCampbell]

You can get reusable dessicant packs and they change color... the color tells you if they've absorbed about as much as they can and should be baked to reset them.  

Baking them (only bake packs designed to be baked because not all dessicant packs can be reset) raises the temperature of the dessicant so high that it's forced to give up any moisture and re-dries the packs.    Once they cool off, you put them back into sealed bags (so they don't just start absorbing any moisure when not needed).

As far as the fogging up... that's simple.  Check the "dew point" value in your forecast.  The dew point will vary based on the humidity level in the air.  It's the magic temperature at which the air will not be able to hold any more moisture and water will condense (typically as fog or rain).  But it turns out if any equipment is colder than or just very close to this temperature it will fog up.

In astronomy we use dew-heaters to deal with the problem.  The heater is a band or strap that we wrap around the optical tube at the front (just behind the objective lens) and it's job is to keep that part of the lens at least 5º warmer than the dew point.  By putting the band "just behind" the objective (instead of on it or in front of it) heat is trapped inside the optical tube and warms the glass.  If it were forward of the glass then that heat would just escape into the air without warming up the optics.

If the optics get too warm, you can get heat currents inside the tube and that will create some blurring.  The so the goal is to get the optics "just warm enough" to dodge the dew... but no warmer.

I have actually run across climate-controlled storage for camera gear.  It looks like a little refrigerator and it's designed to dry the air inside and also to keep it warm enough that introducing the gear to a warm moist environent wont have same effect as taking a beer mug out of the freezer.  I've never used such a storage device, but I know that they exist.

[kvbarkley]

This assumes that the amount of moisture in the lens/camera is the same as the outside air. In this case, the humidity in the lens appears to be higher than outside, causing it to fog sooner.

[RobertTheFat]

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@kvbarkley wrote:

This assumes that the amount of moisture in the lens/camera is the same as the outside air. In this case, the humidity in the lens appears to be higher than outside, causing it to fog sooner.

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That's what it looks like to me too. Water has somehow gotten into the lens, and any looseness in the zoom mechanism is insufficient, under normal usage, to allow it to escape.