1) This is the really daft one - is it OK to put a wet lens on a housing before you get in the water? There will be a bubble of air between the housing and the lens, and I'm wondering if that might cause problems.
2) Slightly less daft - I'm thinking about getting some lighting. Given how powerful video lights are nowadays, what sort of results might I get if I used something like a Fantasea Radiant Pro 2500 instead of a strobe for taking stills? A good high-power video light costs about as much as a decent strobe, but I don't know how the light output compares because strobes have their output given as guide numbers. Any thoughts?
Thanks for putting up with my silly questions.
Teleopsis.
Hi Teloepsis,
Some of these wet lenses are manufactured that there will be no vacuum between the port and the lens so even if you screw on the lens on top water "will" enter between the two as there are holes provided. They are also made to specifically have a layer of water so a vacuum will not work. Inon has a wet lens with a dome in front that works with a vacuum between the two. So in such a case water will NOT enter. so depending on the lens is the use.
As for your second query, strobes are your best option for stills. Lights are no substitute. Two such lights will work for stills BUT you will need very large apertures and slow shutter speeds and the results are nothing as compared to strobes. They will work well for video though. There are enough discussions on this on WP so check that out.
Totally agree with Diggy - and there's no such things as daft questions (it's the answers that are sometimes daft )
Definitely strobes.
The bubble issue is a good point and one of the potential problems with wet lenses.
If you mount the lens in air once you get underwater, remove the lens and gently shake/wipe the bubbles off. This is crucial! Obviously if you remove the lens for the water at any point, you will need to repeat the process.
Strobes output is measured in Watt/Seconds. they provide a very intense light for a very short period of time. Lights do not match up (yet!)
Adam
Thanks all of you, those are really helpful.
Cheers
Teleopsis
The typical duration of a strobe is 1/1000th of a second. Typical shutter speeds run from 1/60th to 1/250th. If you are using light(s), there is more of a chance that a moving subject will blur, unless you use a faster speed. The sequence is the shutter opens, the strobe fires (freezing the action), then the shutter closes.
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