Photographing in Foggy Conditions

[jon w.]

Does anyone know if it is possible to reduce the effects of fog or

other atmospheric haze when shooting at night - on B and W film?

Normally one would use a red filter, or even infra-red film, to clear

haze (I don't know about fog), but isn't this related to the

wavelength of natural light? I doubt a red filter would have any

effect if the light sources are all artificial, though admit I

haven't really tried this out.

I know from initial attempts that film is more sensitive to fog than

the eye (real fog, not the metaphorical kind that x-ray machines

causes), so it would be useful to know who to counter this, because I

do a lot of work in Venice, which is very prone to fog in Winter.

Thanks.

[ole_tjugen]

The film doesn't care if the light is natural or artificial, except insofar as the distribution of wavelengths differ. But since most artificial light (incandescent) contains more red relative to blue than daylight does, try a red filter... Or infrared film. You won't know what works until you've tried!

[john_cook1]

Ole is correct (as usual) that there's little which can be done to eliminate the fog.

 

My advice would be to take advantage of it. I have used fog as a "selective retouching tool" to hide city billboards, powerlines and graffiti. Fog helped me to make pictures in a local city park just next to a highway which looked like they were taken in the great north woods of Canada.

 

Now, if I can just figure out how to get some moose in the shot...

[michael_chini]

Actually if you print at a lower contrast grade, you may lose some (but not all) of the fog. You can burn in specific areas at a higher contrast grade after that.

[Glenn McCreery]

Fog, because it is composed of very small water drops, scatters predominantly the shorter wavelengths of light (blue). But it still scatters longer wavelengths. This is why yellow fog lights are only marginally effective on cars. So, as the others have said, a red filter is the best that you can do with normal film. A red filter placed over the artificial light might work just as well as a lens filter. Infrared film would probably work even better.

[pvp]

<I>Now, if I can just figure out how to get some moose in the shot...</I><P>

Or maybe you could get some guys from the Elks lodge...

[nomennescio]

I like fog. So if I understand this correctly. A blue filter should (at

least marginaly) increase the fog effect?

[michael_briggs2]

I think one should distinguish between "fog" and "atmospheric haze". If by atmospheric haze ones means the effect that reduces the visibility of objects a few km or few miles away, then a filter will help. This haze is typically caused by very small particles that preferentially scatter blue light, so any filter which removes blue light will make a clearer and higher contrast image. Progressively stronger minus-blue filters are yellow, orange, red and IR.

 

For "fog" as the water-in-the-air effect that can reduce visibility to a tens or hundreds of meters (yards), I don't think a filter will make much diference. This effect is similar to a cloud at ground level. The water droplets are larger and the scattering less dependent on wavelength. Fog and clouds both look white, suggesting that a filter won't change their visibility. (Yellow, orange, etc filters can increase the contrast between clouds and a blue sky by their darkening of the sky. If the sky was a grey color and clouds white, filters wouldn't change the relative brightness difference.) Of course, the cost of experimenting with what a filter will do is low, so it is worth a try.

[jon w.]

Thanks everyone. I suspect that a red filter will have little effect, but I'll give it a go (although losing two stops at the light levels involved is also a problem). The fog density in Venice is often so high as to prevent getting any detail at all, and at that intensity, it's difficult to know how to incorporate the effect meaningfully into a picture. I attach my one attempt to do so (by combining the blur of a long exposure with fog diffusion), but I don't think it was a great success.<div></div>

[jon w.]

This is another attempt to use fog - I think it's a bit cliched, but others like it and maybe the diffusion in the upper half of the image (to do with light) matches the blurring in the bottom half (to do with time).<div></div>

[ralph_barker]

FWIW, Jonathan, I think the second shot is more effective. The first image strikes me as over-exposed - getting too much bloom from the lights, and not taking advantage of the potential of the people-in-foggy-darkness sort of mood. Personally, I'd embrace the fog and try to emphasize its contribution to the mood of the city. But, it depends on what you are trying to achieve with the images.

 

While I'm certainly not an IR expert, I'd think that the IR component of the street lights would be quite low, and much of that IR component, it seems to me, would be absorbed by the fog - all making IR exposures rather difficult, or excessively long. Then again, that might be used to your artistic advantage.