Fogged Lens - brainstorming?

[rpcrowe]

I have been shooting with my 90mm f/2.8 Tamron Macro Lens for years and have never been confronted with this problem. I visited the San Diego Zoo Safari Park (AKA: Wild Animal Park) for the early (8 am) entry into their annual Butterfly Jungle. It was quite chilly (I would guess it was 45-50 degrees F.) on the walk from the front gate of the Safari Park to the entrance of the Butterfly Jungle. The Butterfly Jungle is kept heated and humidified. I would expect that the temperature was about 90-95 degrees F. and the humidity must have been pretty close to 100%.

My lens immediately fogged up. The bad thing about the Tamron is that the front element is deeply recessed in the lens barrel. I have always liked this factor, since I don't need to use a lens hood. However, the problem with the deeply recessed front element is that I cannot effectvely reach it with a lens cloth to clean off the fog. I waited for a long-while in the hope that my lens would clear and then just gave up the ghost and determined to come back at another time. I am thinking that the deeply recessed front element may have had a bearing on the lens not clearing. Luckily I have a yearly pass to the park and live fairly close...

I am trying to brainstorm solutions and am suggesting them as they come to mind...

Here are my possible solutions to this problem. Can anyone suggest another solution?

1. Use a clear filter to cover the front element. This won't prevent fogging but, will allow me to clean the fog off of the filter with a lens cloth. Other photographers who were using lenses with more accessible front elements were able to clear their lenses...

2. I have once used a lens coating for my eye glasses which prevented/reduced fog. I would be reluctant to use this on a lens but, would have no qualms about using this on a clear filter...

3. Carry the camera wrapped in a plastic bag inside my coat which would keep the camera/lens warmer and thus closer to the ambient temperature of the Butterfly Jungle. This last seems like the best idea (perhaps combined with a clear filter it may do the job)...

4. Opt to shoot later in the day when the outside temperature is closer to that of the butterfly enclosure. That is the easiest option but, later in the day, there are crowds of people. OTOH, later in the day, the butterflies tend to be more active...

5. Use another lens with a more accessible front element. I am thinking that my old 28-135mm f/3.5-5.6 IS lens might be the ticket, perhaps with the addition of a extension tube. The zoom capability might make shooting in the enclosure a bit easier...

[Manfred M]

Richard - this is going to be problematic, even if you wipe of the front element of the lens or filter until your lens warms up.

What you are seeing is condensation due to the temperature of the lens being below the dew point for the level of humidity in the butterfly house. Wipe off the condensation and it will come right back as soon as you have cleaned it because the temperature of the body of the lens is still below the dew point.

Solution - seal the lens in a ziplock bag with most of the air removed before entering a hot and humid environment. The consensation will form on the outside of the bag and you can wipe it off at will. Once your lens is up to ambient temperature (or at least above the dew point temperature), no more condensation.

If you can carry the lens at a higher temperature than in the butterfly house, there won't be any condensation because you will have kept the lens at temperatures above the dew point.

I get to experience this when I do outdoor photography in the middle of the winter. The camera is fairly useless until it warms up after coming in from the cold.

[Polar01]

Richard: how about taking a soft sided cooler, put camera in plastic bag, put into cooler, drop in a couple hot packs, seal cooler and when you get there remove camera from bag. As camera is warm you should not have problems.

Cheers:

Allan

[rpcrowe]

Manfred and Allen...

Thanks for your help and contributions. I was thinking about Manfred's advice but, it would probably take quite a while fr the camera to warm up enough that the condensation would not accumulate.

I have also thought about, Allan's solution. I think it would work quite well. However, I also suspect that transporting the camera/lens inside a jacket would probably keep the gear warm enough.

It was a frustrating situation because the buterflies were so darn pretty and there were relatively few people in the enclosure at 8:00 AM.

I am going to try the jacket routine and then, if that fails, I will try the heating element. I have a heating pad that we use under our dog mother's beds to keep the puppies warm. I could have this on low and then unplug it for a while and finally wrap the pad around the plastic bag enclosed camera/lens...

[HenkB]

I imagine the jacket routine would work if you can get comfortable with a camera in there with you. Presumably your car will be warm. Or do they still leave the heaters off SoCal cars? I like the idea of putting a gel hot pack (such as are bought in pharmacies and [microwave] heated for use as a compress) in a camera bag. Further wrapping the camera with body cap, dismounted lens with mount cap, hot pack and plastic bags all around for safety (from the gel pack) in a towel for further insulation sounds good to me, too. Like Manfred, my problem is the opposite of this but the happy result is that, with the shooting environment so cold, the warm camera works, no questions asked.

[Manfred M]

The only issue that I do get with keeping my gear under my coat in the winter is that the body transpires and is a good source of additional humidity; so if the camera is a bit cold, you can "pre-fog" it. Hence the suggestion of protecting it by keeping it in a sealed plastic bag.

[DanK]

I've had the exact same experience in a butterfly zoo. I had my Canon 100mm macro, which doesn't have a recessed element, but nonetheless, the condensation is something to avoid.

This is one circumstance in which I would follow Richard's suggestion #1, and have a filter on the lens. I did, when this happened to me, and it is a lot less worrisome to wipe off a wet filter a few times than to keep swabbing at the front element of the lens. Also, it does not take that long for the thin sheet of glass in the filter to warm up enough to stop generating condensation. You can always take it off after the gear warms up, if you want, although with the kind of lighting used for macro, I don't think it makes much difference.

I also now use the plastic bag solution.

Just for fun, here's one I took the day this happened to me, with the UV filter still on. This is with the 100mm and a 36mm extension tube.

[rpcrowe]

[QUOTE=DanK;298800]

This is one circumstance in which I would follow Richard's suggestion #1, and have a filter on the lens. I did, when this happened to me, and it is a lot less worrisome to wipe off a wet filter a few times than to keep swabbing at the front element of the lens. Also, it does not take that long for the thin sheet of glass in the filter to warm up enough to stop generating condensation.

I have wondered if the front element being so far recessed prevented the glass from warming up as fast as an element more exposed to the ambient temperature might do.

A fellow camera group member mentions that he keeps his camera bag on the floor of his car for the trip to the Safari Park and that he keeps the camera/lens in the bag until he opens it in the butterfly environment.

I think that a heat source just might be the answer. I have a heating pad which I use to keep my rescue puppy litters warm. I might have the pad plugged in to warm up (on low) and then unplug it from the wall and place it in my camera bag. The trip from my home to the park is less than a half hour and then another 15 minutes or so walk between the gate and the Butterfly Jungle. That would mean 45 minutes to an hour between house and butterfly exhibit...

Of course, I might have the problem in reverse if I wanted to shoot in the cool park enviroment after I finished shooting in the Butterfly Jungle.

Oh well, photography is always a series of decisions and compromises!

Here is another thought! I have never used a protective filter on my Tamron. Fitting a protective filter on that lens would mean that the filter would be located over and a half one inches (~ 38mm or so) in front of my lens. I wonder if this might not cause image quality problems? There is a Tamron specialist coming to the Calumet Camera store in Escondido today, who I could ask. However, I am due to drive up to Hesperia, CA (over a hundred miles away) to rescue a poor little Maltese who has been in the shelter up there for a long ime.

[Polar01]

Richard instead of the heating pad, nuke a gel pack, drop a cloth over the lens in your camear bag place the hot gel pack on top of the cloth and zip the camera bag up, do this just before you leave for the park. Like Manfred it is the other way with the cold, so I just leave every thing in the back of the car 24/7 however I always have fresh batteries fully charged.

Cheers:

Allan

[Dave Humphries]

Hi Richard,

One of the UK butterfly houses I visited last year had a neat solution - one of those warm air hand driers like you get in washrooms/toilets - it is intended for visitor's glasses really (so they don't trip over - or tread on the exhibits ), but a quick waft under that was much quicker than waiting for my P510 bridge camera's front element to warm enough to get above dew point.

As you said, the DSLR, with thin filter over the lens was much quicker to clear naturally.

Of course, I might have the problem in reverse if I wanted to shoot in the cool park environment after I finished shooting in the Butterfly Jungle.

You shouldn't have the problem in reverse, unless you have a lot moist air trapped inside the lens - then I guess you might get condensation on the inside of the front element and lens barrel (if metal). Pumping the zoom (if it is a zoom lens!) and exercising the focus from end to end might help displace this in favour of cooler, drier air from outside. I haven't had this problem, so I'm guessing here though.

Cheers,

[Ken MT]

All that you wanted to know about lens fogging and possibly a bit more

http://www.cameratechnica.com/2011/0...-condensation/

[krancmm]

Good Day, I'm a brand spanking new member to this site and rather intimidated by the level of expertise I see on the forums, so I've been a lurker.

However, I had to chime in on this topic as it's a consistent problem for my location. In this humid sub-tropical area our morning humidity typically runs about 95-97%. If I bring out my camera from whole-house A/C, the lens will immediately fog even if the temperature is EXACTLY the same indoors and out. It's the discrepancy between indoor and outdoor humidity that affects the dewpoint in this case.

Using this handy calculator http://andrew.rsmas.miami.edu/bmcnoldy/Humidity.html
My house
Inside: Temp 78°; Humidity 50% = 57.83° Dewpoint
Outside: Temp 78°; Humidity 97% = 77.08° Dewpoint
At same temperature there's still 20° difference in dewpoint = FOG

Butterfly Garden
Temp 95°; Humidity 97% = 94.01° Dewpoint

Scenario with your camera warmed with body or heat packs to Butterfly Garden temp:
On entrance: Temp 95°; Humidity 50% (pretend) = 73.39° Dewpoint
At same temp, 21° dewpoint difference = FOG. Greater difference if your outdoor relative humidity is lower than 50%.

To get the same dewpoint – no fog - as the butterfly garden, your camera would need to be 118° at 50% humidity when you entered.

My solution to just leave camera gear in a non-A/C space obviously can't be yours.

Perhaps if you were to follow the suggestion to use a little cooler, you could try a moist heating pad or a microwave moist heat warmer (the ones filled with flax or rice) to get the humidity up as well as the temperature. That should at least lessen the "fog" time for early morning visits.

[Glenn NK]

. . . . one of those warm air hand driers like you get in washrooms/toilets - it is intended for visitor's glasses really (so they don't trip over - or tread on the exhibits ), but a quick waft under that was much quicker than waiting for my P510 bridge camera's front element to warm enough to get above dew point.

As you said, the DSLR, with thin filter over the lens was much quicker to clear naturally.

I was going to suggest putting the lens/camera in the sun indoors for a while to pre-warm it, but the hand-dryer seems to be the simplest and most practical if it's available.

A filter won't help much - it will keep fogging up until it's warm enough, as will the camera and the lens.

A zoom lens really compounds the problem when it extends and sucks in warm, moist air.

Going from warm and moist to cooler and drier will never be a problem - in fact it might be a good idea to run the zoom in and out a few times to remove any residual humidity.

The post by Monica (krancmm) covers the physics very well. She knows what she's talking about.

Glenn