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UltravioletPhotography

Light Leaks through Viewfinder


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In UV photography it is a fact that any light leakage can influence or deteriorate the final outcome. No wonder as the UV scene typically is anywhere from 6 to 12(13) stops lower than visible light itself. The main concerns tend to be directed towards cutting IR contamination which requires using the very best sharp-cutting filters such as the Baader U2" Venus filter.

 

However, besides leakages seeping through filter holders and adapters, there is another potentially severe source: the camera itself. More specifically, the viewfinder of a SLR/DSLR.

 

To learn the reality, do look at these captures of a flowering Sedum acre. At present I am stranded on an isolated island and unfortunately, my workhorse SB-140 is on the mainland and thus inaccessible. Thus, I had to do timed exposures in UV often in the area of 15 to 25 secs.

 

Without shielding the view finder I got this result,

 

SEDU_ACR_T1307095254_JUV_LIGHT_LEAK.jpg

 

Only by completely covered the viewfinder eyepiece could I obtain a non-contaminated exposure.

 

A final note is that diffuse daylight (and long exposures that might induce minute movement) prevents the finest details from being rendered. For this a more directional lighting, such as a flash, is required in order to boost micro-contrast.

 

SEDU_ACR_I1307095257_UV.jpg

 

Both with D600, UV.Nikkor 105 lens and the Baader U2" (Venus) filter, daylight.

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I also got a light leak from an open port door.

Go figure.

*****

 

You can lift those dark blocked areas a bit with the brightness slider from an NX2 Color Point to reveal a little more detail. Not as much as if you had used a UV flash, but it helps. (Set opacity to Luminance to avoid colour changes.)

 

Alternately, in Photo Ninja hit the Highlight slider as many times as needed to pull back the right side of the histogram, then hit either the Exposure slider or the Illumination slider to push the histo back to the right. Sounds like these ops should cancel each other out, but no, it works in many cases to open up things a bit. The Illumination slider maintains the contrast relativity of the scene if not over pushed.

 

The Photo Ninja Shadows slider is less useful in these situations.

*****

 

Stranded on an isolated island ? Sounds cool !!!

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I did not check my gear sufficiently before going by boat to this island. Thus, critical items were left on the mainland. I can get there by the end of the week but not now. Self-inflicted patience is required.

 

Fooling around a bit with UV landscapes and IR multiband composites instead.

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