I’m finding ultraviolet photography to be one of the biggest challenges I’ve come across in the photographic process in years. Such a huge learning curve.
Due to the short bandwidth of ultraviolet light, the reflective transmittance doesn’t seem to travel as far as visible light, plus this also causes a focus shift issue as photographing in infrared does.
With the sensitivity of the converted camera, I have been able to pick up the ultraviolet spectrum at a decent iso (around 800 – 1600 as opposed to 200 – 400) and live view permits achieving a fine focus if I take the time to really review and adjust before I shoot.
More of the problem seems to be in the lenses. Glass, air space and the cement used to join elements in a lens all interfere with the UV transmission. True UV transmission lenses (made with quartz-fluorite elements instead of glass) are still manufactured and a few older ones can be found second hand but these are way beyond my price range at an approximate cost of $3000US and up.
Fortunately ultravioletphotgraphy.com has a list of true and “accidental” lenses for ultraviolet photography work. I managed to pick up one of the Steinheil 50mm Cassarits recently and imediately noticed a difference. While not a spectacular shot, it is the first time I’ve been able to achieve focus on any subject farther away than about six inches.
This was shot midday 1/4 second, f8, iso 1600 using a Hoya U360 and S8612 bringing it to around a 360-365nm light source. The Steinheil triplets have been tested to have a cutoff of around 320nm. I am looking forward to testing this lens (as well as an older Cassarit 100mm) with a Hoya U340 to see if I can achieve a deeper UV cutoff point.
Here is the same photo with false color applied.