Dew Point Temperature

[LuckyJames]

Is there a temperature below which lense fogging becomes a problem . I have a dark site trip planed to Portal, AZ in May and the average night temp will be arround 45F (8C). Should I be concerned about fogging? I will be shooting with a Canon EF 24mm lense.

Appreciate any expert guidance.

[kvbarkley]

Generally, the dew point is really low in the desert, especially before the monsoons start. Here in albuquerque we rarely get dew. That said, you probably should prepare for it.

[jrhoffman75]

https://nightskypix.com/condensation-in-camera-lens/

[LuckyJames · Accepted solution]

Thank you for the link and pointing me to Clear Outside. That's an awesome app.

[wq9nsc]

You could go prepared with chemical hand warmer packs to use just in case to keep the lens warm but it isn't likely you will run into conditions where the dew point will be an issue in that location.  Other than breathing on your lens front element, the concern would be if the temperature is expected to increase during your shooting time from a change in wind direction or a front coming from where the air temperature begins to increase and your camera lens will heat more slowly due to its thermal mass.

The only time I have had to deal with lens fogging is when I enjoyed too much air conditioned comfort in my car or truck on the way to shooting a late spring or summer sports event and my camera gear was far cooler than the outside air.  After doing that once and having to wait for the gear to get close to equilibrium, under those conditions it now rides either in car trunk or enclosed pickup bed in its Pelican transport cases rather than me sacrifice my air conditioned comfort 🙂

It is much more common to fog the viewfinder (or live view screen if your face is close to it) and although a nuisance to you, it won't impact the image quality. 

Chemical hand warmer packs are inexpensive and can be stored for a long time as long as the packs remain sealed.  Once activated they stay warm for 8 hours or more.  I always keep a couple of unopened pairs with me when heading out to shoot in the fall or winter.  I hate wearing any kind of glove when doing photography but a pair of those in my pockets allow me to quickly warm my hands.  When I was photographing eagles on an 8 degree windy day in Iowa last month I had a pair in my coat pockets and I was tempted to see if I could fit another pair in my shoes.  They get and stay toasty warm as long as you don't completely seal them off from oxygen.

Rodger

[jrhoffman75]

Hi Rodger. The conditions you are describing are different than the conditions where lens fogging during astrophotography is a concern. 

Where I live in New England it is an issue in the fall. Warm days and cool nights. Same situation that has the grass covered in dew or the car covered in dew in the morning. For us generally September thru mid-October. 

[wq9nsc]

John,

We get the same humidity conditions here and I have to take this into consideration with the Celestron telescope in the spring, summer, and early fall but winter here is like the desert with very dry air most of the time.  Fall is the worst for me with the telescope when air temperature often varies radically over a short time at night as competing fronts fight for control and I usually have it out shortly after dusk rather than in the early hours before dawn. Those early hours in Spring would be even more problematic as the air often warms radically a few hours before dawn.

Why does most of the stuff we want to photograph occur under less than lovely conditions?  I have shot football and soccer in blowing rain, sleet, and snow and wildlife seems to prefer weather that is not pleasant for us.  I could always try to take up studio or product photography but that wouldn't be nearly as interesting for me!

Rodger

[Waddizzle]

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@LuckyJames wrote:

Is there a temperature below which lense fogging becomes a problem . I have a dark site trip planed to Portal, AZ in May and the average night temp will be arround 45F (8C). Should I be concerned about fogging? I will be shooting with a Canon EF 24mm lense.

Appreciate any expert guidance.

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Dew Point Temperature is not a constant.  It is a function of primarily three variables; ambient temperature, relative humidity, and barometric pressure.