Preventing fog on lens at DVinfo.net

Yean Tan · April 20th, 2006, 10:39 PM

Just came back from an island called Pulau Ubin in Singapore where it is reputely the best place for stargazing.
Tried to get a timelapse of the stars but the lens kept getting fogged up througout the night.
Anyone encountered or have any solutions? I'm thinking of taping a heat pack onto the camera.

Jim Harring · June 27th, 2006, 07:17 PM

http://www.cabelas.com/cabelas/en/te...exId=cat200007

EK Scope Dope USD $3.99 Used for hunting rifle scopes.
Cabelas has a good reputation in USA and this item is very light, so won't cost very much to ship, even to Asia.

They have other items too...

John M. McCloskey · June 28th, 2006, 07:35 AM

did you allow your camera time to get to outside temperature or take it from a cool place to hot and start videoing or hot to cold too quickly. If so set your camera in the temperature you will be videoing in for at least 30 minutes to allow the camera to get accustomed to the temp difference.

Marcus Marchesseault · June 28th, 2006, 06:11 PM

I don't think it is a matter of letting the camera acclimate. The changing conditions during the night will cause dew and a camera lens pointing up will catch that dew. A can of compressed "air" may help dry the lens, but a hair dryer or heat pack might be better. I think a gentle blast from the hair dryer every once in a while might be easiest to implement. The compressed "air" cans may cool the lens which could make the problem worse. Don't use a fueled heat source since their exhaust contains a lot of water which may initially condense on the lens. Obviously, don't apply significant heat as it may adversly effect the camera.

Mark Slade · June 28th, 2006, 10:11 PM

Marcus has it right....except I wouldn't use a can of air. Too often something nasty comes out that you don't want on your lens. I am an amateur astrophotographer(in addition to playing at video during the day). The problem is indeed dew....formed by the lens being at a different temp than the air. When I am in my observatory I can use a hair dryer as Marcus suggested if it is really heavy dew. When out in the boonies(we sometimes pick up and go to darker skies) I use a "heat rope" attached to a battery. You can get this "heat rope" at American Science and Surplus. I believe they are on the web. They have a store in Wisconsin. It's basically nichrome wire in a cloth sleeve. You wrap it around the end of your lens. The DC current heats it just enough so it warms the lens. You don't need much heat...just a degree or two above ambient is enough. It's best to turn it on at the start and leave it on. Once dew forms it takes forever to get rid of it with the heat rope. Another option is to take a look at Kendrick Dew Heaters. They make a very nice system for telescopes that are easilly adapted to any size lens. It's what I use on my 12 inch scope in the observatory when the dew isn't heavy. Works a charm.
Mark

April 20th, 2006, 10:39 PM	#1
Yean Tan Regular Crew Join Date: Sep 2002 Location: Singapore Posts: 30	Preventing fog on lens Just came back from an island called Pulau Ubin in Singapore where it is reputely the best place for stargazing. Tried to get a timelapse of the stars but the lens kept getting fogged up througout the night. Anyone encountered or have any solutions? I'm thinking of taping a heat pack onto the camera.

June 27th, 2006, 07:17 PM	#2
Jim Harring New Boot Join Date: May 2006 Location: Tampa, FL Posts: 12	Various riflescope "safe" defoggers should work http://www.cabelas.com/cabelas/en/te...exId=cat200007 EK Scope Dope USD $3.99 Used for hunting rifle scopes. Cabelas has a good reputation in USA and this item is very light, so won't cost very much to ship, even to Asia. They have other items too...

June 28th, 2006, 07:35 AM	#3
John M. McCloskey Major Player Join Date: Jun 2005 Location: West Point, MS Posts: 313	did you allow your camera time to get to outside temperature or take it from a cool place to hot and start videoing or hot to cold too quickly. If so set your camera in the temperature you will be videoing in for at least 30 minutes to allow the camera to get accustomed to the temp difference.

June 28th, 2006, 06:11 PM	#4
Marcus Marchesseault Trustee Join Date: Nov 2005 Location: Honolulu, HI Posts: 1,961	I don't think it is a matter of letting the camera acclimate. The changing conditions during the night will cause dew and a camera lens pointing up will catch that dew. A can of compressed "air" may help dry the lens, but a hair dryer or heat pack might be better. I think a gentle blast from the hair dryer every once in a while might be easiest to implement. The compressed "air" cans may cool the lens which could make the problem worse. Don't use a fueled heat source since their exhaust contains a lot of water which may initially condense on the lens. Obviously, don't apply significant heat as it may adversly effect the camera.

June 28th, 2006, 10:11 PM	#5
Mark Slade Regular Crew Join Date: Jan 2006 Posts: 121	Marcus has it right....except I wouldn't use a can of air. Too often something nasty comes out that you don't want on your lens. I am an amateur astrophotographer(in addition to playing at video during the day). The problem is indeed dew....formed by the lens being at a different temp than the air. When I am in my observatory I can use a hair dryer as Marcus suggested if it is really heavy dew. When out in the boonies(we sometimes pick up and go to darker skies) I use a "heat rope" attached to a battery. You can get this "heat rope" at American Science and Surplus. I believe they are on the web. They have a store in Wisconsin. It's basically nichrome wire in a cloth sleeve. You wrap it around the end of your lens. The DC current heats it just enough so it warms the lens. You don't need much heat...just a degree or two above ambient is enough. It's best to turn it on at the start and leave it on. Once dew forms it takes forever to get rid of it with the heat rope. Another option is to take a look at Kendrick Dew Heaters. They make a very nice system for telescopes that are easilly adapted to any size lens. It's what I use on my 12 inch scope in the observatory when the dew isn't heavy. Works a charm. Mark