UV torch – (unwanted) effect on image

For my studio shots, I have been using the Nightsearcher 365nm UV torches to light the subject while adjusting focus. There are times when I have left these on while shooting flowers. My thinking is that if I use shutter speeds of 1/160, there will be little time for the UV torch to impact on the final image.

Here is an illustration of this effect with a striped Gazania; although they were shot on 2 separate occasions with different flowers, they were from the same species. I’ve included visible shots to show they are indeed the same variety.

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Striped Gazania – visible
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Striped Gazania – visible
Striped gazania - UV (Quantum X2D)
Striped gazania – UV (Quantum X2D)
Striped Gazania - UV (Quantum X2d with UV torch left on)
Striped Gazania – UV (Quantum X2d with UV torch left on)
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Striped Gazania IDS1 (Quantum X2D)
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Striped Gazania IDS1 (Quantum X2D with UV torch left on)
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Striped Gazania IDS2 (Quantum X2D)
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Striped Gazania IDS2 (Quantum X2D with UV torch left on)

Notice the increased yellow in the images with the UV torch left on? And that despite using 1/160 sec shutter speed. I have noticed similar when shoot orchids, where the yellow contamination from the UV torch is very prominent against the blue of the orchid in UV.

Hence to protect the images I shoot from any UV torch light contamination, I now cover the UV torch while shooting indoors with flash; I find it easier than switching the UV torch on and off.

Boon

Equipment used: Olympus EM-5, Coastal Optics 60mm F4, Baader U filter, IDS1 & 2 filters, Quantum X2D flash, Nightsearcher UV torches