I’ve often hear that insects can see into the ultraviolet range, and that flowers display special patterns in that range that are not observable to humans. As it’s the middle of winter, with not a flower in sight, I thought I’d post a few of my experiments with the UV range.
Fair warning: I’ve taken some Ultraviolet photography, but I’m not very good at it yet(here’s someone who is better at it). I’ve experimented with a few filters for it, but my camera isn’t the best at taking photos in that range either.
In the process of experimentation, I’ve made my own filter out of an epoxy filter. This filter allows light with wavelengths shorter than 450 nanometres to pass through, while blocking anything greater than that. This mean that it allows blue, violet, and ultraviolet light to pass. I call this filter my ‘Short Pass filter’
This filter is in a ‘blind spot’ with my Canon T3i’s software. No matter how I try, it cannot apply a white balance to the filter. By default, every photo is ‘extremely purple’. With a white piece of paper to balance, the colour changes to ‘very purple’. Maybe, if I play around with the white balance settings for a while, I can get the photo to look ‘Very Purple, with a little bit of blue’. My previous full spectrum camera did not have the problem to the same degree, but for both cameras, the image on the viewscreen would not be in the same colours as the actual photo taken. I know that it is due to the colour range displayed, though, not a physical property of the epoxy filter. when I add my UG11 filter to my Short Pass filter to cut off all visible light, I am again able to reset the white balance.
I call it a problem, but it really isn’t. With the faulty colour balance, the photos taken have a surreal look to them that I haven’t been able to replicate with my other filters. Case in point: many petunias have complex patterns in their flowers. With the Short Pass filter, they look… well, see for yourself.
The first photo is in the visible range, as usual.
The second one is taken with my Short Pass filter.
The photo at the top of the post, by the way, is one of these flowers, zoomed in further.