Now I do like taking photos of flowers indoors, as it allows me to be in control of the various settings including pose of the flower. But sometimes I do like to shoot flowers in the garden using ambient light. Clearly this involves the use of a tripod and wired remote control to prevent any shake. Also, it is preferable not to have any wind to cause movement blur of the flower.
So here are some of the flowers I have growing in the garden currently, all shot with Olympus E-M5, Coastal Optics 60mm F4 APO and Baader U filter using aperture mode. I am aware that below 1/10 secs, I will not be able to handhold and shoot even with the in-body image stabilisation of the Olympus E-M5. Hence the images below would not be possible without a tripod, or the use of a flash.
Benefits of ambient UV-imaging:
1) It captures the background of the flower better than when using flash (which typically has a dark background).
2) Some would say that UV-images taken with ambient light looks nicer.
3) No need to carry large strobes or flash about for the shoot.
Disadvantages of ambient UV-imaging:
1) It requires longer exposures (even with higher ISOs) and hence requires to be done with camera mounted on a tripod.
2) This may not be possible if the subject is growing in the shade due to the lack of UV light.
2) Not possible to shoot if there is strong wind around, due to motion blur of the subject (when a flash is required).
I do not tend to carry a tripod with me when I go out to take photographs; I only tend to use it in my garden. So while I do like the background of UV images shot in ambient light, however I prefer being able to shoot flowers without a tripod. Which is why I am always interested in flash with good UV-output. One such macro flash which looks interesting is the Venus KX-800, which has two flash heads on extending flexible arms (each 48cm long) and a guide number of 58m at ISO 100. That should be powerful enough for UV-imaging, particularly when the flash head is as close to the subject as possible, assuming the flash tube is uncoated.