How to prevent fogging on lens?

[DarkShadow]

You can't prevent it entirely but i found it much less if the glass is not subject to sudden extreme temp changes.for example the camera is in a heated car or A/C then the exposed to sudden severe temp changes out of the car. I always put the camera in the trunk of the car where it does not get warm or cool and usually never have that issue not that i ever noticed any ways but the lenses always live with a lens hood and i don't even bother with lens caps any more.

 

[astroNikon]

Have you guys ever looked at real telescopes.
They have big lens hoods / dew shields (excluding observatory domes)
and some of them are heated
==> Heated Dew Shields And Lens Shades For Celestron Telescopes | Astronomics.com

here's a good writeup about the entire problem, but instead of "dew shield", think "lens hood".
Dealing With Dew: Dew Heaters, Dew Shields and More - Sky & Telescope

But RowdyRay was right in his statements.
a breeze/wind will prevent dew from settling, just like it does from preventing dew/frost from settling on your cars windshield in the mornings.

On long over night exposures you can have the same phenomenon on your camera lens. A lens hood will prevent that angle of dew settling from getting on the lens, dependent upon the angle, etc. when there is no wind/breeze.

You could just set up a umbrella over the camera, up high enough not to affect the FOV. I've seen that used in the past - it was just zip tied to the tripod. Of course, only good on nights with no wind.

FYI, you could just use a piece of paper (preferably black) and some tape to make a lens hood. On telescopes ppl use that thin posterboard to make low cost, simple dew sheilds.

 

[ac12]

Every time when I try to shoot through the night, my lens fog up within a few minutes. Ive left the camera out for the whole day and it still fogs up. The weird thing is, it doesn't happen to my friends when shooting together. The main difference is he has lens hood and I don't.

If your statement is accurate, you need to investigate more.

• Your lens fogging within a few minutes
  • This will not be solved by a hood, unless it is raining or if were were IN a fog.
    
  • That sounds like temperature difference condensation.
  • That also tells me that the camera was some place else before, maybe in a different environment. So where was the camera before the "few minutes?"
• I doubt the hood is the only difference. You need to talk to your friend and find out EXACTLY what he does to prepare and transport his gear, and compare to what you do. And you have to be anally detailed in this comparison, or you could miss the critical difference. I would bet that there is a significant difference in what he does.
  
• Was the camera in your cold air conditioned car, which was colder than the ambient air? Or were you at the site the entire day, with the gear out, before setting up?

So for those who shoot night time lapse, there's no sure way of avoiding fogging? Sure I will use a lens hood. I have one, just didn't have it with me at that tkme. However getting to the location and the opportunity never comes easy and I hope to have a sure method to rely on.

There is no "silver bullet" quick easy answer, which is what it sounds like you are looking for.

You will have to do your own research and try the various methods, to see what works FOR YOU, your gear, your location and the camera elevation angle.

• Change the location and what worked before in another location may not work in the new location. Or what failed in another location may work in the new location.
  
• Elevate the lens to a higher angle, and the front element is more exposed to vertical desending moisture.
• Wider lenses have shorter less effective lens hoods, for blocking falling moisture. Maybe you need a custom rectangular hood, or a compendium. But a compendium is like a small sail, it will catch the wind.
  
• Can you setup a canopy/shelter to setup the camera under? This will obviously limit your vertical elevation.

Finally

• Make a gear checklist, and use it, so you don't forget your lens hood or other item.
• Make a procedure checklist and use it, so you don't forget to do something that you need to do.

 

[SCraig]

There are a number of ways to help prevent fogging on optics but no sure-fire way of doing it. On my rifle optics and my shooting glasses I use a Nikon Anti-Fog "Fog Klear" Cloth that works quite well. I get them at a local range that sells them but they are available in many places. Plain old shaving cream works OK to; wipe it on, let it dry, polish it off. Most places that sell glasses also have bottles of anti-fog fluid that work to some extent (some better, some worse).

 

[TCampbell]

This is an everyday problem for many astrophotographers.

No need to leave the camera out all day ... and this may be part of the problem. A "warm" lens wont collect dew. A "cold" lens will. It's all about the dew point. When the lens temperature reaches or drops below the dew point, dew will form on that surface.

Check the weather forecast ... you need a forecast that includes the "dew point". If the dew-point is expected to be within about 5°F of the actual temperature then dew is likely. Dew will form on metal or glass surfaces long before it forms on other surfaces because these surfaces give up their heat faster. This is why you can get dew forming on lenses when technically the ambient air temperature is still above the dew point.

A dew-hood (or any hood) will help. The rule for telescope dew shields is that the "hood" should stick out about 2x as far as the diameter. e.g. if the lens had a 100mm diameter then you'd want it to go 200mm forward. But this could be a problem if you're trying to shoot with a wide-angle lens.

Dew doesn't "fall" on the lens... it "forms" on the lens. Some people think the dew hood is somehow acting as a shield. What it's actually doing is trapping air near the surface of the lens ... keeping air from circulating in and out as easily. Air still circulates since the front is open... but it slows the rate. Doing this allows air at the surface to be warmed and trapped so that it'll be just above the temps needed for dew to form.

The ultimate weapon against dew is the dew heater. This is a strap that wraps around the front of the lens and works a bit like an electric blanket. They run on 12v power. The straps themselves are actually pretty cheap... but the dew controllers *can* be moderately expensive (or really expensive depending on the controller). The controllers job is to keep the optical surfaces just *barely* warm enough to stay above the dew point without being too warm. The problem with getting too warm is that you'll get a very thin layer of air just on the surface of the lens which is much warmer than the rest of the air. It'll do what hot air does... rise. This will create turbulence with warm and cold air mixing and that will create distorted optics ... which of course degrades your image quality.

Most dew straps use the RCA "tulip" type plugs. They nearly all run on 12v power. But the power is "pulsed" (toggles on & off for a fraction of a second to control how hot the strap can get. If you just feed the strap continuous 12v power it'll get too warm.)

The controllers usually have multiple ports and sometimes multiple channels (dual channel is popular). This is because an astrophotographer might have a strap on their main imaging scope, another on their guide-scope, another on their finder-scope, another on their hand-controller and they may even have straps on telescope eyepieces (to keep them from fogging up). Since small components don't need as much heat as large components, a "dual channel" controller will have a couple of knobs.

Expect to pay $100-150 for basic controller of any decent quality. Straps are usually a lot less (for a camera lens... expect to pay much less than $50 ... probably $25-35).

You would also need a 12v power source. Most astronomers just use a rechargeable 12v battery. For just one camera lens... this would not need to be a very big battery (maybe a small 7 amp hour battery... these are probably around $30). You'll also need to recharge the battery after each use. An automotive battery charger would typically do the trick ... but most people pick up a trickle-charger (battery maintainer) suitable for AGM batteries.



There are ALSO 12v "hair dryers". This is used to save you AFTER the dew forms (so you don't have to pack up and go home). Just a word of warning... these things are really cheap (as in quality). Consider a home hair dryer is probably consuming something like 1500 watts (probably at least 1000 watts). Since watts = volts x amps... and household power might be 110v (here in north america), a 1500 watt hair dryer is drawing something like 13.5 amps (and most household circuits are good for supplying at least 15 amps). Translate this to a 12v battery... and now you need 125 AMPS at 12v to create 1500 watts. Your battery might be able to supply 5 amps... but it's NOT going to supply 125. That means these things are really wimpy. The fan isn't strong (which is good since it takes longer to warm up the air) and it only puts out mildly warm air (not "hot" air). BUT... they are "good enough" to warm the optics to the point that the dew evaporates and will buy you a bit more time. The better solution is to avoid letting dew form in the first place.

 

[ac12]

Tim, that is interesting.
Cuz, the other morning, my car which is parked under a tree, and normally has NO dew on it, was WET with dew.
So the normal protection by the tree did nothing that morning.

 

[RowdyRay]

Tim, that is interesting.
Cuz, the other morning, my car which is parked under a tree, and normally has NO dew on it, was WET with dew.
So the normal protection by the tree did nothing that morning.

There had to be a LOT of moisture in the air. Like fog. Which only happens when it's dead calm.

 

[molested_cow]

 

[AlanKlein]

Stop breathing on it.

 

[RHallock11]

I’ve been taking night motion lapses for almost 5 years now, and when I started, I was living in the very damp and humid city of Buffalo, NY. The humidity would rise from the 60-70% range in the evening to almost 100% in the late/early morning hours, my lens would literally drip. I feel your frustrations.

I found that putting a handwarmer (the pouch kind that you expose to air) or two on the barrel and securing then with a rubber band helped a lot. I live in Joshua Tree, California now, and I get so excited to not have to deal with damp/humid nights anymore. My Syrp Genie would be covered in “sweat” as I call it, and it would always worry me a bit at night on the east coast.

 

[RodKlukas]

Hi all. Every time when I try to shoot through the night, my lens fog up within a few minutes. Ive left the camera out for the whole day and it still fogs up. The weird thing is, it doesn't happen to my friends when shooting together. The main difference is he has lens hood and I don't. Does lens hood make such a big difference? Is there something else I can do to prevent fogging especially for long shoots, like time lapse?

The shade will indeed impede the formation of fog on a lens. But it also makes your images much more consistently good in terms of craft.

A lens shade is like an oil filter on your cars engine. You don't see it doing anything or moving, but you are pretty sure it helps the engine run longer and better.
A tiny tipping forward or back of your setup for composition purposes, without a shade, can suddenly yield an image with flare or glare across the entirety of the image. This glare can flatten the contrast and mute your colors or worse. Flare is not just aperture blade hex refections when pointed at a specular or a strong light source. It is the aberration I mentioned concerned with contrast. Also flare can cause an overexposure in some areas causing a lost in apparent sharpness.

Another good thing is that should your camera/lens unfortunately take a fall, the shade may save all except itself from a major repair.

Just some thoughts.

 

[BryanC]

Hi all. Every time when I try to shoot through the night, my lens fog up within a few minutes. Ive left the camera out for the whole day and it still fogs up. The weird thing is, it doesn't happen to my friends when shooting together. The main difference is he has lens hood and I don't. Does lens hood make such a big difference? Is there something else I can do to prevent fogging especially for long shoots, like time lapse?

Fogging occurs when the glass of your lens is colder than the ambient temperature you're shooting at - humid air cools ad the interface of the glass and moisture precipitates. To avoid that, make sure your camera and lenses are at or above the ambient temperature you'll be shooting at. Bringing your camera/lens out of an air conditioned car or home out into a warmer humid outdoor air is an example. Keep your camera in a non-air conditioned space like the trunk, garage etc so you won't fog when your cool/cold camera/lens hits that warm, humid air

 

[aspen]

i think photo lens hoods from flash-Masters does the trick

 

[paigew]

Get a lens hood and see. I never shoot without a lens hood. It helps with lens flair, protects the lens without any distortion and, just maybe, keeps the lens from fogging up. Lens hoods are relatively cheap and there is no downside to using one.

There is definitely a downside. To me, they were cumbersome. They take up extra space in my bag, so I stopped using them. They also add a tiny bit of weight to the camera.

Do you not just store the lens hood backwards on the lens?


Sent from my iPad using Tapatalk

 

[Scott Whaley]

I have found that if you have your camera and lens in a cool, air conditioned room and then take it outside in a humid setting, it will fog up. I have also found that keeping the camera and lens in a large plastic zip lock bag while in the air conditioned room and keeping it in the bag until it is taken outside helps a lot.