Sunday, March 29, 2020

Reflected UV photography in polarized light II

Today more about those UV polarizers experiments I have done, using special UV polarizers in front of my multispectral camera and UV-Nikkor 105mm lens, for recording reflected UV images. This now uses a UV transmitting filter for circular polarized light. UV filter used was my classic Baader-U filter; sun was used as light source.

[click on image gets you a larger image]

Here now more photographic results I got (took multiple images while rotating the filter), presented as animated gifs....

Roofs of some neighbouring houses showing strong polarizing effect of glass windows and metal:

Butterfly orchid - Phalaenopsis showing only mild polarizing effects:

Succulent plant - Lewisia showing strong polarizing effects:

Reflected UV photography in polarized light shows quite some usefulness, especially if there are (glossy) surfaces which change the polarization angle of light and which the polarizer filter makes visible. Downside is that one needs about 2 stops more exposure, due to the low approx. 25% transmission.

I have now solved the change of focus issue which I previously had.

Some insects are able to see the polarization angle (and btw. we humans can also, but needs some traing: Haidinger's Brush) especially honeybees which navigate using the polarization angle of ultraviolet (UV) light.

I will continue to make more tests later using the other polarizers and also the special waveplates, which allow for circular polarized light.

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site