These custom made filters allow photographers to take UV (blacklight) images using common flashes and a bit of black electric tape. These filters allow film speeds as low as 100 for close up work and exposure speeds as high as 1/400th of a second when used with higher ISOs.
A few points about these filters:
- Seconds are generally caused by errors in the kiln temperature or errors when applying the blacklight glass powder to the base. This creates filters that are thicker and block some UV light along with visible light. Oddly, it can also create tiny holes in the blacklight glass that enhances photos by adding a touch of visible light.
-High end flashes are not recommended as they generally have internal filters or coatings that absorb the UV light before it leaves the flash. These can be removed, but the cost is likely to be far higher than buying a basic off brand flash.
-The best way to mount the filter to your flash is to use black electric tape. Place the filter on the flash head and use four short strips about 1/16th of an inch over the edge of each filter to hold it to the flash and block any white light from existing the flash.. Then wrap a fifth strip around the head of the flash to finish the attachment.
-Absolute dark is not required to use these filters for most photo sessions. Enough ambient light to use your auto focus will generally not interfere with the black light exposure.
-Experimentation has shown us that the best starting setting seems to be 1/200 of a second at f6.3 and 400 ISO.
-TTL metering does not work with black light. You will need to experiment with manual settings.