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UltravioletPhotography

Filters and Fog


Andrea B.

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Here at our end of Mount Desert Island, the fog banks roll in and out, up and down Somes Sound. So I thought a filter test was in order to illustrate the shortwave/longwave fog differences. We know the shortwave UV & violet/blues get scattered more than the longer red & IR wavelengths. How much difference is there in comparative UV and IR photos for a distant scene? A lot, it turns out.

 

Equipment: D600-broadband + 105/4.5 UV-Nikkor

Exposures: f/16 @ ISO-200

Filters: Baader UV/IR-Cut, S8612, Baader-U, BG3, B+W 093

 

The View: Looking across Somes Sound from Southwest Harbor to Northeast Harbor (or Hedge Fund Harbor, as my SigOth calls it). Nothing exotic by way of composition here because I wanted a good fog bank to shoot into. I made two series of shots so that similar shots could be compared because the fog bank is not static.

 

1. Visible with Baader UV/IR-Cut Filter

At first the fog was higher.

foggyViewAcrossSomesSound_visSun_20150720shoreCottageME_35567pn.jpg

 

2. Visible with Baader UV/IR-Cut Filter

It became a little darker after the fog rolled down closer to the water.

foggyViewAcrossSomesSound_visSun_20150720shoreCottageME_35589pn.jpg

 

3. Visible with S8612

This filter didn't do much for the scene except wash out the colour quite a lot.

foggyViewAcrossSomesSound_s8612Sun_20150720shoreCottageME_35593pn.jpg

 

4. UV with Baader-U UV-pass

As predicted the UV-Nikkor cannot "see" into the fog when the UV-pass filter is used.

BTW, the dots in the water are lobster buoys, not dust bunnies.

foggyViewAcrossSomesSound_baadUSun_20150720shoreCottageME_35601pn.jpg

 

5. Blue & IR-pass with BG3

One of those combo filters which can give wild & crazy false colours if you are so inclined.

Cool that a lobsterman zoomed by just as I was shooting.

foggyViewAcrossSomesSound_bg3Sun_20150720shoreCottageME_35603pn.jpg

 

6. B+W 093 IR-pass

Here's the "pure IR" view. Definitely more detail than in the UV version.

foggyViewAcrossSomesSound_093IrSun_20150720shoreCottageME_35583pn.jpg

 

7. B+W 093 IR-pass

The fog begins to lift a bit.

foggyViewAcrossSomesSound_093IrSun_20150720shoreCottageME_35609pn.jpg

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We know the shortwave UV & violet/blues get scattered more than the longer red & IR wavelengths. How much difference is there in comparative UV and IR photos for a distant scene? A lot, it turns out.

 

An interesting start. Since reflection and scattering vary with wavelength, aerosol size and aerosol type, you will find that some scenarios will produce significant differences to these results. In fog for example (a large particulate aerosol), IR does a poor job of "penetrating" it whereas, it can do an excellent job of penetrating some types of haze (a small particulate aerosol). Unfortunately the effects in haze are also dependent on the type of haze, e.g. natural vs pollution, wet or dry haze, small vs large aerosol particulate.

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The IR did "reach" further than the UV in this particular fog bank. But it will be interesting to try similar shots with other scenarios - an Arizona dust storm or some city smog. "-)
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