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UltravioletPhotography

Torch/lens/filter test


Cadmium

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No conclusion about this test yet.

This is a comparison of Schott KV418 and Wratten 2E on the camera lens (alone, not stacked with any other filter),

looking at the MTE 303 torch which is filtered with a U-340 2mm filter.

All settings are the same, same shared white balance also. Only the lens filter is different.

What I 'think' I am seeing here would better be tested on a target perhaps.

For one thing, the very dim ambient room lighting has some IR content, and given the 4s exposure, and since the camera lens filters I am comparing here are both longpass type filters (they see IR),

thus everything in both of these photos look tinted with IR, where as the same shots I did with the KV418 and 2E respectively stacked with Baader UV/IR-Cut filter (which cuts off IR)

look cleaner with no IR tint.

So there is that, but I think I am also seeing a bit of fluorescence with the 2E filter, which is definitely possible, but remember, this is an extreme situation given that the MTE is shining into the lens.

Wratten 2E does fluoresce, but only very slightly, and only when you shine UV on it very close, and you can usually only really see the fluorescence on the edges of the gel.

Anyway, no conclusion here, and this test wasn't really done for this reason, more just to test the difference between those two filters alone compared to the +Baader UV/IR-Cut stacked versions of each,

which really should be tested in a completely dark room to eliminate any ambient light or IR.

This comparison dose seem to indicate that KV418 and 2E block UV about the the same as each other.

The only reason I decided to post this comparison is because of the slight fluorescence I 'think' I am seeing in the 2E shot, but again, very minimal.

I would need to redo this test with all of that in mind to come to a conclusion.

 

post-87-0-40575300-1546313406.jpg

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The Kv418 seems sharper. Maybe the 2E fluorescence is softening the image. Or your gel as fingerprints on it.

 

Be careful not to stare at your uv flashlights for too long you will think you see things. Then you will see nothing at all.

 

Oddly I was testing something similar to this last week with my Led bulbs. Trying to see where I could cut out all signal with long pass filters. Now I wonder how good my long pass filters are. Testing can never end.

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Not a 'fingerprint', nope. The 2E is slightly 'fogging' the image, but again I should point out that this is with direct close illumination.

The Wratten 2E (blocking wavelengths below 415nm) definitely fluoresces. Also, I compared it to the Wratten 2B (blocking wavelengths below 395nm), they both fluoresce about the same.

Even the KV5418 fluoresces slightly, you can mostly only see it on the edges of the glass, and it doesn't show in this pictures, especially because it got out of focus before I shot it.

The UV/IR-Cut doesn't fluoresce, however it may not cut UV as high as wanted, thus the idea of stacking with longpass filters toward the lens, to cut UV/Violet a little bit higher.

Some like to cut off at 435nm.

 

post-87-0-23873200-1546397623.jpg

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