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Why do UV imaging?

Why do UV imaging?

There are many people who love a challenge e.g. climbing Mount Everest, swimming across the Channel etc. UV imaging indeed is challenging for various reasons. 

1) The camera sensor is more sensitive to both visible and infra-red light, than to UV. Hence the UV light required to illuminate the subject for UV imaging needs to be many stops more than for visible-light photography. So either you will need a tripod-mounted camera to allow long exposures using sunlight (where wind and cloudy weather is your worst enemy) or a very powerful uncoated Xenon flash to provide the UV light.

2) The lens will need to pass enough UV spectrum to the sensor to capture the detail of the subject. Most lenses have glass, coatings or optical cements used in the construction, which absorb UV, which make them unsuitable. There are lenses made for UV-imaging, but these are very costly. Fortunately some older lenses can be used for UV-imaging; I shall reveal some lenses I have found to be useful in subsequent posts.

3) The UV-pass filter needs to block enough visible and infra-red light, while letting through as much UV as possible. The reference UV-pass filter currently is the Baader U Venus 2″ filter (not the 1.25″ version which has IR-leak). But there are cheaper alternatives out there, which I will also mention in a later post.