• Ultraviolet Photography

Sand Fluorescing Red

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#21 baffe


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Posted 30 November 2014 - 16:00

That only seems to be. This is because in that areas the sensor is overexposed. The blue value remains at 255 (8bits) and the others come up so resulting color changes to white. But of course there is some white light. I usually use UG11 to reduce that if necessary.

The homemade USB powered lamp shows much more white light. I bought (and payed) a 365nm 1W led but it is not. Is something round 380nm. But the value is not reliable because my spectroscope shows internal fl at uv (I'm working on that).

The "highly sophisticated electronics" is a simple resistor limiting the led current to 370mA (nominal value) and a on/off switch. At a voltage of 5VDC from usb a possible solution.

#22 JCDowdy


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Posted 04 December 2014 - 17:02

View PostDamon, on 30 November 2014 - 04:45, said:

John--is it safe to say I can use my Canon 30D setup and not worry about this light leakage affecting my images?

The 30D at least seems your better choice of the two from what you have shown. However, standard practice is of course to remove as much Vis & NIR from the excitation source as possible while blocking same from the sensor. These inspection lamps you have are used primarily for leak detection with fluorescent tracer dyes so presumably the secondary bandpass of the filter must not interfere significantly with that function. I think you have demonstrated that this secondary bandpass is falling within the camera Vis/NIR sensitivity. Your photographic work looks great as is, but these wavelengths could be further attenuated if you want, if you can find a suitable large filter.