Timelapse in high Humidity

[HowLiu]

Yesterday I had the perfect conditions for a nighttimelapse. no Moon, and clear sky. a very rare opportunity where I live.

Setting up Timelapse with my camera and go! I thought..

There was 95% humidity and of course my camera lens was badly effected by this humidity and the lens-glass completely condensed. Results badly..




Therefor my question is, how do you prepare for long timelapse nightsky with high humidity?

How to protect the camera?




thanks for sharing your thoughts!




How

 

[RustierOne]

HowLiu wrote:

Yesterday I had the perfect conditions for a nighttimelapse. no Moon, and clear sky. a very rare opportunity where I live.

Setting up Timelapse with my camera and go! I thought..

There was 95% humidity and of course my camera lens was badly effected by this humidity and the lens-glass completely condensed. Results badly..

Therefor my question is, how do you prepare for long timelapse nightsky with high humidity?

How to protect the camera?

thanks for sharing your thoughts!

How

Good question, How. In a humid environment, dew will begin to form on an optical surface if its temperature is low enough relative to the dew-point temperature. This temperature is often included in weather forecasts, which can help predict if you will have a problem. What happens is the exposed lens radiates heat to the clear sky and thus cools. When its temperature drops below dew-point, air in contact with the cool lens also cools and looses its moisture, which settles as dew. Amateur astronomers deal with this problem by having electric heating strips surrounding the exposed lens to reduce lens cooling.

One thing that helps is to install the lens hood, which limits how fast the lens cools. If you are imaging in a location that has access to electricity, you can utilize an electric hair dryer to heat the lens above the dew-point. It may be necessary to do this repeatedly during the night as the previously warmed lens again cools to the dew-point temperature. You can find portable dew removal guns that run off an automobile battery, for use at remote sites. Here's one source:

http://www.lymax.com/adg/


As for protecting the camera itself from dew, you might lay a cloth over the camera body with the lens protruding through. This will slow cooling of the lens body and separate it from damp air. I hope this helps.

Best Regards
Russ

 

[Retardation]

I've worked in the same and worse conditions a few times and have overcome this problem. I first get the focus point on the lens and then tape it in place. I then wrap two heat pads (the type you use in your clothing to keep yourself warm) around the lens barrel and tape them into place.

This keeps the temperature high enough to stop condensation. I've gotten great results in doing this.

It also helps to set up an umbrella over the camera/lens if you can, it helps!

 

[DuncanDovovan]

Retardation wrote:

I've worked in the same and worse conditions a few times and have overcome this problem. I first get the focus point on the lens and then tape it in place. I then wrap two heat pads (the type you use in your clothing to keep yourself warm) around the lens barrel and tape them into place.

This keeps the temperature high enough to stop condensation. I've gotten great results in doing this.

It also helps to set up an umbrella over the camera/lens if you can, it helps!

GREAT idea!

 

[bngreenchev]

When I do my night shots I leave my gear in the car with the bag open to bring the camera gear's temp to what it is in the car and outside temp, when driving to my location no heat is on my car that way when I arrive the gear is the same temp as what it will be setup in.

 

[HowLiu]

thanks for the solutions.

I also thought yesterday about the dryer. but what kind of battery do you need for 6 hour Timelapse sessions..

i'm going to do some testing..

 

[HowLiu]

Retardation wrote:

I've worked in the same and worse conditions a few times and have overcome this problem. I first get the focus point on the lens and then tape it in place. I then wrap two heat pads (the type you use in your clothing to keep yourself warm) around the lens barrel and tape them into place.

This keeps the temperature high enough to stop condensation. I've gotten great results in doing this.

It also helps to set up an umbrella over the camera/lens if you can, it helps!

thanks R,

how long was your session?

would be interesting to know the cooling time of these packs..

 

[DuncanDovovan]

HowLiu wrote:

Retardation wrote:

I've worked in the same and worse conditions a few times and have overcome this problem. I first get the focus point on the lens and then tape it in place. I then wrap two heat pads (the type you use in your clothing to keep yourself warm) around the lens barrel and tape them into place.

This keeps the temperature high enough to stop condensation. I've gotten great results in doing this.

It also helps to set up an umbrella over the camera/lens if you can, it helps!

thanks R,

how long was your session?

would be interesting to know the cooling time of these packs..

These stay warm a couple of hours. You can always take a couple with you and replace them between shots. You'd probably need a easier solution to attach them to the lens than tape. Perhaps a piece of flat rope?

 

[RustierOne]

HowLiu wrote:

Yesterday I had the perfect conditions for a nighttimelapse. no Moon, and clear sky. a very rare opportunity where I live.

Setting up Timelapse with my camera and go! I thought..

There was 95% humidity and of course my camera lens was badly effected by this humidity and the lens-glass completely condensed. Results badly..

Therefor my question is, how do you prepare for long timelapse nightsky with high humidity?

How to protect the camera?

thanks for sharing your thoughts!

How

It looks like there are a lot of different ways to deal with dewing of optics. Here's one made specifically for a DSLR.

http://www.kendrickastro.com/astro/dew_cameracozy.html


It's not necessarily just high humidity that's the problem. If it's warm enough (above the dew-point temperature) no dew will form, even with high humidity. An example is in the warm, humid tropics, where dew may not be as frequent as in the cool, moist temperate climates. Just a thought.

Best Regards,
Russ

 

[Retardation]

HowLiu wrote:

Retardation wrote:

I've worked in the same and worse conditions a few times and have overcome this problem. I first get the focus point on the lens and then tape it in place. I then wrap two heat pads (the type you use in your clothing to keep yourself warm) around the lens barrel and tape them into place.

This keeps the temperature high enough to stop condensation. I've gotten great results in doing this.

It also helps to set up an umbrella over the camera/lens if you can, it helps!

thanks R,

how long was your session?

would be interesting to know the cooling time of these packs..

Mine was 4 hours with no problems. Some of the heat packs I've seen last 6-8 hours. As for securing it I've even used a long football sock (clean of course!), which may have helped insulate the whole package. It wasn't pretty but works for me. I do take extras with me. It's a very cheap solution.

 

[just Tony]

I was going to provide a link to Kendrick. Orion Telescopes is another source.

To everyone who is less familiar with the dew problem:

Lens hoods help a great deal but not a lot of people know why. The problem is radiative emission of the (initially) warm lens out into cold, deep space. What a lens hood does is to provide a nearby surface that is also receiving IR being emitted from the ground. The net result is that the lens hood is warmer than the sky, and a hooded lens is therefore in a "less cold" environment. I have had dew form on a refractor scope lens during a long observing session, and I was able to evaporate the dew completely in about 15 minutes by pointing the telescope toward the ground. It was all because the ground was warmer than outer space. (Technically speaking, in IR terms the dominant object up there is the upper atmosphere... but the temperature behind it is 3 degrees above absolute zero).


A heater tape allows one to work all night. The tape is low wattage and the idea is to provide a level of heat that is about the same, or slightly more, than the rate of heat flow coming off the lens. It doesn't take much power. I've used 12V 7 Amp-Hour batteries all night long and they only got down to about half of the charge. You won't just plug the tape into 12V directly. Get a variable controller so you can set just enough power to get the job done.