net begonnen met duiken wrote:> Just wondering.> Does any manufacturer produces a hid light that comes with the> possibility to control the brightness infinitely variable between 25%> lets say 100%.> I know some torches with control from 70% to 100% but i like to use it> for OW photography and 70 yo 100% simply is not good enough.
You probably will have to use a filter. HID is an arc and requires a certain, and high voltage, to just bridge the gap. If they exist they would be *very* expensive WRT other HID's Hot wires can be controlled just by changing voltage but then there is a color problem
There are some very powerful LED solutions on the market and this year may prove to be a major one. At least one company has a product that is about 30% more efficient. LED's maintain the same color temp, just get brighter or dimmer.
net begonnen met duiken wrote:> "Mike Painter" <mddotpainter@sbcglobal.net> wrote in message> news:<PGI2e.8243$zl.5481@newssvr13.news.prodigy.com>...>> net begonnen met duiken wrote:>>> Just wondering.>>> Does any manufacturer produces a hid light that comes with the>>> possibility to control the brightness infinitely variable between>>> 25% lets say 100%.>>> I know some torches with control from 70% to 100% but i like to use>>> it for OW photography and 70 yo 100% simply is not good enough.>>
You probably will have to use a filter.>> HID is an arc and requires a certain, and high voltage, to just>> bridge the gap. If they exist they would be *very* expensive WRT>> other HID's>> Hot wires can be controlled just by changing voltage but then there>> is a color problem>>
There are some very powerful LED solutions on the market and this>> year may prove to be a major one. At least one company has a product>> that is about 30% more efficient.>> LED's maintain the same color temp, just get brighter or dimmer.>
with all respect, I do not think LED's are not even close to HID when> it comes to lightpower.> Even more, the 5W Luxion consumes about the same Amps as a 10W WA HID.> The output however is quite dissapointing, especially under water.
So a 5 watt at one amp draws 5 watts and the HID at one amp draws 10 watts. Unless you use Lumins there is nothing comparable between the two.
That being said LEDs are solid state devices and are about at the stage the Z80 was when introduced at about 4 MHz. A 3 watt Luxion has just been introduced that gives the same light as the 5 watt.
I suggest you take up on your own advise!> any professional flash DOES have brighness control, color control,> flash-durationcontrol, adjustable timing for flashpoint etc etc.>
These are NOT professionals, these are the divers that would normally use an automatic or TTL flash, however, if you need to adjust the light output of a HID then the best thing, after using the cameras aperture & shutter speed, would be to use diffusers or neutral density filters on the flash.
I do use a variable power flash unit underwater, however, that's so that I can balance my depth of field with the aperture and ambient light / flash illumination with the shutter speed. You seem to have forgotten the any camera with FP shutter will have a limited range of shutter speeds that can synchronise with the flash (where both blinds are fully open).
This is not the case with many digital cameras or any cameras with interleaf (lens) shutters.
