[UV] A simple tutorial for reflected UV photography, version II

I updated my simple tutorial for reflected UV photography version II

This is intended for beginners to have a simple and affordable solution
at hand to start with.

Dr Klaus Schmitt said:

I updated my simple tutorial for reflected UV photography version II

This is intended for beginners to have a simple and affordable solution
at hand to start with.

Click to expand...

What about for Canon mounts? What's the focusing helicoid you refer to?

Asher

Unfortunately Canon DSLRs have no useful UV sensitivity (mentioned
in my text and also linked to a test I made some time ago), so I had
to also invest into Nikon.

A focusing helicoid replaces the missing focusing ability of a barrel lens
(such as an enlarger lens for instance), like an adjustable extension tube.

Dr Klaus Schmitt said:

Unfortunately Canon DSLRs have no useful UV sensitivity (mentioned in my text and also linked to a test I made some time ago), so I had to also invest into Nikon.

Click to expand...

Hi Klaus,

You probably know about it, but for point light sources it is relatively easy to determine the spectral sensitivity for a given digital sensor or film. All one needs is a special grating filter like the "Star Analyser" (obviously named after its usefulness in astrophotography).

Your relative exposure difference test is of course adequate to determine the Nikon's better usability for UV photography, but silicon based sensors in general have limited sensitivity in the (near) UV region. Shorter than 380nm their sensitivity drops rapidly and below 320nm there is little left, if anything.

Cheers,
Bart

Bart_van_der_Wolf said:

Hi Klaus,

You probably know about it, but for point light sources it is relatively easy to determine the spectral sensitivity for a given digital sensor or film. All one needs is a special grating filter like the "Star Analyser" (obviously named after its usefulness in astrophotography).

Your relative exposure difference test is of course adequate to determine the Nikon's better usability for UV photography, but silicon based sensors in general have limited sensitivity in the (near) UV region. Shorter than 380nm their sensitivity drops rapidly and below 320nm there is little left, if anything.

Cheers,
Bart

Click to expand...

Why not just use film?

Bart_van_der_Wolf said:

Hi Klaus,

You probably know about it, but for point light sources it is relatively easy to determine the spectral sensitivity for a given digital sensor or film. All one needs is a special grating filter like the "Star Analyser" (obviously named after its usefulness in astrophotography).

Your relative exposure difference test is of course adequate to determine the Nikon's better usability for UV photography, but silicon based sensors in general have limited sensitivity in the (near) UV region. Shorter than 380nm their sensitivity drops rapidly and below 320nm there is little left, if anything.

Cheers,
Bart

Click to expand...

@Bart, thanks

but it is not that easy, this is why I use a calibrated electronic spectrometer (Ocean Optics) and calibrated light sources for my studies. Still, direct access to the sensor of a camera cannot be had, just analysis of its output given a well known light source. A colleague of mine has done that tedious work for a Nikon camera HERE. But you are correct to assume that beyond 370-380nm the sensitivity rapidly drops and beyond 320nm no response is there anymore - also my personal findings.

@Asher: sure, film works easily down to 300nm and there also is no IR leakage problem, which makes filtering much easier. It just doesn't fit my working habits anymore.