Need some advice about filming in Greenhouse regarding condensation

[Lucas Kao]

Hi,

I am filming a site specific theatre project in Botanic Garden, where the each scene takes place in a different areas in the Garden at night time. Guided by usher, the audience walks through different spaces, and at a point in the story the audience is taken into a glasshouse from outdoor. Thats when the problem occurs, the lens fogs up upon entering from outside and it takes more than a few minutes for the condensation to disappear when I should be filming.

Is there any tips or tricks that allows me to shoot continuously without worrying about condensation of the lens when going from outdoor to inside glasshouse?

Here are a few possible solutions I thought of and their problems, is there a way to not use more than one camera and lens?

1) Plant B Camera with B Lens inside the glasshouse before the show starts, so the B camera + Lens and that is climate-ised to the greenhouse temperture.
Problem: There is a few different locations, so need more than 2 cameras and lenses. No enough budget to hire additional cameras.

2) Plant Lens B inside the glasshouse before the show starts, so the lens that is climate-ised to the glasshouse temperture. And quickly switch the lens before the audience comes in.
Problem: Does the Sensor fog up as well? Need to hire additional lens.

3) Arrive before all the audiences and wait for the condensation to settle.
Problem: Not being able to catch some of transitional footage between scenes.

Thanks a lot!

 

[Imamacuser]

You could rubber-band heat packs around the circumference of your lens to keep it at the same temperature as the glasshouse.

 

[Darren Levine]

Another question: are your cameras/lenses weather sealed/resistant? I think your proposed plans will work fine, but here are some further thoughts:

I was in the galapagos with a c100 and a sigma 18-250mm lens, and at one point early morning on the boat a big gust of moisture fogged both the outer and some inner elements of the lens. an L lens would have fared better due to weather sealing.

Get a lenscoat/wrap the lens with a blanket. also may help to put a UV filter on the front so you can quickly remove it.

 

[abreu-canedo]

Do you have the luxury of directing? If so, for the sake of budget and keeping the number of cameras down, I would simply use that as a moment to cut. If you're following the people into the space, you may cut, go into the space, climatize your camera/lens, and now you film them coming into the space.

If if this is more of an event documentation type shoot, then I'd go with the extra camera.
-Best of luck!

 

[mcbob]

Was just dealing with this the other day on a quick doc shoot. What worked was shooting with my B camera while I put the A camera beside one of the exhaust fans... The movig air helped dry the camera.
A hairdryer can also dry the lens etc, but may have its own issues. Your best bet is placing an alternate camera in the greenhouse beforehand.

I like the heat pack idea, would be interesting to test

 

[Bruce Watson]

Guided by usher, the audience walks through different spaces, and at a point in the story the audience is taken into a glasshouse from outdoor. That's when the problem occurs, the lens fogs up upon entering from outside and it takes more than a few minutes for the condensation to disappear when I should be filming.

That's just the laws of physics talking to ya. The lens is colder (having been outside) than the dew point of the air inside. Whenever this happens, the air right next to the cold object looses a little temperature to your cold and massive lens (heat flows only from hot to cold, remember your high school physics). In doing so, that air's temperature can drop down below the dew point. This in turn forces some of the water vapor contained in that air to condense. And the nearest thing it can condense on is... your lens.

Yes, this is exactly what happens when you bring a cold beer from the refrigerator to the picnic table. The condensation on the beer is the exact same mechanism.

There are a couple of ways to deal with this. First, you could keep the temperature of the lens at the same temperature as the problem air. Maybe put the camera/lens in a "rain coat" will be sufficient, IDK. Think of this as the beer koozie method.

Second, you could find a way to lower the dew point of the air in the building -- it's a greenhouse, it has fans. Talk to your local greenhouse manager about your problem; odds are he/she can help. All it may take is a few minutes of blowing out the greenhouse and pulling in some cooler/dryer outside air. A 5C drop in temperature may be all it takes. Or not. Too many variables for me to know from here, that's for sure.

Third, you can put a fan on you (yes, you and your lens) to stir up the air around the lens to keep a specific pocket of air from forming around your lens that can then transfer sufficient heat that it drops in temperature below the dew point. All this takes is an assistant handling a fan, and some luck. Might take more air flow than you want to use, might be noisy, etc.

By far the easiest way to deal with this is to film on a day when the temperature contrast between the night air and the inside temperature is not so great. A warmer night is your friend. Just sayin.

 

[Lucas Kao]

Hi all,

Really appreciate all your feedback and thoughts!
Will try the heat pack, removing filter and the raincoat method around the lens tomorrow.

To Darren:
The camera (FS7) is weather sealed, but the lens I was using was a vintage zoom lens which doesn't have weather sealing so it fogs up quickly.

To Rafael and mcbob:
Its a theatre production so I can't have the luxury of stop and start the audience, I will get a 2nd camera and put it in the greenhouse just in case.

To Bruce:
Thanks for the detailed explanation of the causes,
The greenhouse I am filming in are botanic walk path and there are many plant species inside that are sensitive to temperature changes so your 2nd method won't be feasible. I am a one man band cameraman so the 3rd method won't work as there won't be any time to do that as the performance starts happening once the audience walks in. But I will try your 1st method with the rain coat, it may work!

Thanks!