Posted by Andy Astbury on January 29, 2012 at 4:05 AM
15 days ago I shot a 200x 20sec star trail sequence with my 14-24 f2.8, in conditions of -4C and experienced no problems at all.
24 hours later I was out with my friend Mike, both using the same setup, D3+14-24mm, at a different location, and we both experienced lens fogging from around frame 50; ambient temp was about the same as the previous night - we both put the problem down to shooting next to a large lake.
The following night my son and I went to the top of a 400m hill to shoot, I was still using the D3+14-24mm f2.8, he was using a D300 with a Tokina 12-24mm.
Both cameras were running on their built in intervalometers.
My sequence was ruined from around frame 50 due to fogging, but his was perfect with no lens fogging.
Ambient temperature during the shoot was around -3C with a slight breeze.
My son was hooting without his lens hood, so I wondered if my problem was the something to do with the large fixed one on my 14-24.
So I borrow a 24-70mm, leave off the lens hood, and take it out in 4 degrees of frost at midnight and shoot a test sequence to catch around 1 hour of rotation - around 150 frames - no problems at all.
Last night that very same friend Mike came with me, using his D3s plus a 24-70, we set up and trip the cameras to catch 300x 20sec frames and retire to the car for the duration.
Net result - both lenses fogged from around frame 60!
At all times I should say that the lenses have been exposed to the ambient conditions for at the very least an hour before shooting commences, and in all instances the fogging has been on the outside of the front element.
Now I've come across various ideas on the net from heat packs to battery operated fans, but I would really appreciate hearing from anyone who has experienced this problem themselves and how they solved it.
Many thanks in advance
Posted by Myer Bornstein on January 29, 2012 at 12:34 PM
Think about attaching a pair of handwarmers to the lens with elastic bands, should help with fogging
Posted by Andy Astbury on January 29, 2012 at 2:57 PM
Thanks Mye - someone else has just suggested that as well
Also had a suggestion about dew heaters as used for telescopes etc: which also sounds good but I was wondering about how big a gelcel they'd need - handwarmers sounds the way to go first - thanks again
Posted by David Prichard on January 29, 2012 at 11:01 PM
Andy,
Have you considered packing them in a desiccate prior to use? While it does sound environmental perhaps some ambient dampness on the lens may be contributing.
Posted by Peter Cross on January 30, 2012 at 12:26 AM
My understanding of what goes on is that you're out on a nice clear night which is perfect for radiational cooling to happen. Since you're pointing the lens towards the sky, they cool down faster than the ground which retains more ambient heat. Hence the moisture in the air will condense on them first. Astronomy folks do have dew heaters which are bands with heating elements in them that wrap around the front by the objective lens and keep it warmer. But in addition to the strip, you wouldf need a controller as well as a power source. This is more elegant but way more expensive than the hand warmers. As I recall toe warmers have some sticky on them to keep them on the top of the toes. So they might negate having to wrap an elastic around them. Certainly worth a shot. I usuall pay $1 for a pack of 2 hand warmers. Cheap enough and they last for hours -- some more than others.
Posted by Wick Smith on January 30, 2012 at 9:03 AM
A great resource is the blog from Kevin Adams - Digital After Dark. He's tried every gizmo under the sun.
He's got some white papers from his seminars that discuss this in detail & a lot of options. I don't know if he specifically addresses this issue on the blog at this point.
Discussion
5 replies24 hours later I was out with my friend Mike, both using the same setup, D3+14-24mm, at a different location, and we both experienced lens fogging from around frame 50; ambient temp was about the same as the previous night - we both put the problem down to shooting next to a large lake.
The following night my son and I went to the top of a 400m hill to shoot, I was still using the D3+14-24mm f2.8, he was using a D300 with a Tokina 12-24mm.
Both cameras were running on their built in intervalometers.
My sequence was ruined from around frame 50 due to fogging, but his was perfect with no lens fogging.
Ambient temperature during the shoot was around -3C with a slight breeze.
My son was hooting without his lens hood, so I wondered if my problem was the something to do with the large fixed one on my 14-24.
So I borrow a 24-70mm, leave off the lens hood, and take it out in 4 degrees of frost at midnight and shoot a test sequence to catch around 1 hour of rotation - around 150 frames - no problems at all.
Last night that very same friend Mike came with me, using his D3s plus a 24-70, we set up and trip the cameras to catch 300x 20sec frames and retire to the car for the duration.
Net result - both lenses fogged from around frame 60!
At all times I should say that the lenses have been exposed to the ambient conditions for at the very least an hour before shooting commences, and in all instances the fogging has been on the outside of the front element.
Now I've come across various ideas on the net from heat packs to battery operated fans, but I would really appreciate hearing from anyone who has experienced this problem themselves and how they solved it.
Many thanks in advance
Also had a suggestion about dew heaters as used for telescopes etc: which also sounds good but I was wondering about how big a gelcel they'd need - handwarmers sounds the way to go first - thanks again
Have you considered packing them in a desiccate prior to use? While it does sound environmental perhaps some ambient dampness on the lens may be contributing.
http://www.kadamsphoto.com/ncphotography
He's got some white papers from his seminars that discuss this in detail & a lot of options. I don't know if he specifically addresses this issue on the blog at this point.