How easily can sauna damage EOS R and RF 24-105?

Jun 23, 2020
How long will EOS R and RF 25-105 f4 (with Hoya antistatic protector filter) survive in sauna heat without any harm? I took couple pictures in sauna. I was there max 20 seconds and the door was open. Heath must have been some where around 40–65 °C (104–149 F) at the height I took photos and it was quite dry since I didn’t get any fog to the lens.

I haven’t exprerienced any issues and the camera didn’t welt hot. I’m still worried about If I damaged my gear (mostly about moisture).


The dark side - I've been there
Nov 7, 2013
Hi NewHm and welcome to Canonrumors!

I suppose only the Canon developers could answer your questions credibly. And surely they won't.

So for me it is just guessing:
From what you describe (20 sec, max 65°C ambient, not much humidity) I would expect no problems to your gear because within < 30 seconds there is not enough time for lens and body to heat up noticeably. If you let them cool down a few minutes before the next few shots this should work.

Danger comes from heat:
- lubricants have a specified operation temperature. Too hot and they flow away. Too cold and they solidify.
- plastic can deform, you'll lose alignment of optics or even wose mechanics could jam
- electronic parts with heat losses (sensor, processor) cannot be cooled anymore and get damaged.
I would expect all this to take effect after a few minutes. But I am not sure.

Danger comes from too low humidity (relative):
- materals like lubricants, sealings and everything else flexible but also condensator, batteries or other electronical components dry out.
I would expect all this to take effect after hours. But I am not sure here, too.

Danger comes from too high humidity (relative, e.g. in bio sauna or steam bath):
- condensation on electronical circuits, schortcuits
- etc.
I would expect this to take effect after minutes or hours. But again I am not sure.

I hope, I am right and your gear will serve you flawlessly a lot of years.

Mt Spokane Photography

I post too Much on Here!!
Mar 25, 2011
Long term exposure to temps over about 130 degrees F may shorten the live of the camera. Typically, damage comes from all the factors mentioned above, usually because someone leaves their gear in a hot car where temps can easily exceed 140 degrees in some areas. Its a slow process, not a fast one. If lubricants fail then wear progresses faster, if cements weaken that glue lens elements together, they may separate at some point.


EOS 5D Mark IV
Apr 25, 2011
I'd say as long as you can hold the camera comfortably, it's not hot enough to be in danger.

Humidity, though, could be a problem. A normally prepared sauna should have a dew point slightly above the human body temperature, so a camera may get some water condensed on (and in) it. Nevertheless, it's just distilled water, so it shouldn't have any long-term effects.

Jack Douglas

CR for the Humour
Apr 10, 2013
Alberta, Canada
Just thinking out loud. Can humidity be more than 100% such as it often is when we're in humid climates or rain forests? My camera goes into those types of situations, it seems without problem and as mentioned, the moisture if any internal, would probably be considered distilled water and dry with little effect. Or am I off track with this line of reasoning?



EOS 5D Mark IV
Apr 25, 2011
Just thinking out loud. Can humidity be more than 100% such as it often is when we're in humid climates or rain forests?
With the absolute humidity (grams per liter) being the same, the relative humidity increases when the air cools.

The idea of the sauna is to have a hot dryish air that nevertheless becomes more than 100% humid when it is cooled to the body temperature. The moisture that forms on the body in a sauna is normally not sweat, but dew.

On a camera that is cooler than a human body, the dew will form even faster.

However, if the door was open for quite a while, the air was unlikely that wet, even if its humidity was controlled by an automatic steamer.
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Jun 23, 2020
Thanks for replies.

I was asked to photo and became worried afterwards. It was a small traditional sauna that’s warmed by wood and the door was open to the yard.

Good signs are probably that I didn’t notice any condensation in sauna and the camera didn’t felt particularly hot or wet. Actually my clothes felt also dry after the quick visit to sauna.

I still will never again take a photo in sauna.
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