Xenon bulbs for tungstein lights?

[Giancarlo Bianchi]

Does anyone knows of any manufacturer making xenon Daylight balanced bulbs that could be use on any tungstein light systems?

Could be a really nice alternative to HMI, or the sturdy kinoflos.

 

[Dan Hudgins]

Simpler...

Simpler...

Does anyone knows of any manufacturer making xenon Daylight balanced bulbs that could be use on any tungstein light systems?

Something simpler would be to use the blue filtered "daylight" lamps, not sure where to find them now, but NOS might be around, and boost them.

We boost our tungsten lamps from 120v up to about maybe 160v, you can get 2 stops more light for the same size bulbs. The bulbs do not last long so we have a foot switch near the camera, you step on it to click the boost relays from 95v up to 135v to maybe 160v just before you start the camera then let off the foot switch right after the camera trigger. You can also use a DPST push button to do this for the camera remote trigger.

The extra K would help with the RED ONE (tm) since you get MUCH more blue light with the lamps over run. Having the lamps idle at 95v also makes them last longer for setup, but the life boosted gets very short as the voltage goes up, at plus 3 stops you might get 20 seconds before they pop, depends on what kind of lamp they are, the ones with the "industral" heavy filament seem to last longer, or the big mogal base bulbs like 500w mogal in a scoop makes more light than a 2K when boosted. The fixture and wire should be rated 600v so that you do not arc.

ColorTran (tm)'s name came from their xformer that ran 2800K lamps at 3200K and 3400K. One time I plugged something called a "powerflood" xformer into a ColorTran (tm) xformer to double over run a 500W mogal, and got the shot just before the lamp went, but it was bright and very white light! Would have been three stops underexposed without that.

Also boosting lets you get more light on house circuits without renting generators, you get 400amps of light for 100amps of power.

Since the RED ONE (tm) sensor is 5500K, and people are shooting under 2800K without filters, if you boost the lamps to 3700K to 3900K there should be less blue noise and better looking images. People were saying that they cannot use a 80A because of the light loss, but if you boost the lamps you get MORE light rather than less with a filter, maybe you can do both and come out even?

The fixtures shoud have a cover glass in case the lamps explode, or something, quartz lamps may shatter, but so far we have not had any lamps blow up, just out.

 

[Erik Bien]

Mr. Hudgins, you know you're quite mad, don't you? :tongue:

Actually, Don's Bulbs has a cool print-it-yourself bulb voltage slide rule that can help you calculate the tradeoffs in output, color temp, lamp life and voltage. He'd also be the guy to ask about Xenon globes for your favorite instrument.

 

[Dan Hudgins]

Blue vs. Red brightness...

Blue vs. Red brightness...

Actually, Don's Bulbs has a cool print-it-yourself bulb voltage slide rule that can help you calculate the tradeoffs in output, color temp, lamp life and voltage.

Thanks for the info about the slide rule device, my Brother collects those.

Those ColorTran (tm) type devices were very popular with profesional photographers in the late 50's to maybe the 70's. The "PowerFlood" looks like it was from the 30's, we got it at a photo swap, the guy that was selling it plugged one 60watt lamp into it and flipped the switch to boost and "pop" went the lamp. He sold it to us for something like $10 because he did not know that you need to plug in 500watts of lights or the voltage is very high, like over 200volts, the load brings down the peak voltage to something like 160 to 180.

The stop gain for BLUE light is more than for RED light, hence the K shift to higher K values. The gains given on the slide rule are probably for visual max which is in the yellow-green and so does not show as much gain in exposure as you get on Ortho or Blue sensitive film, or in this case the Blue sensors of the RED ONE (tm) sensor.

Since the ratio of IR to BLUE+UV changes, if you boost the voltage you get better color from the Bayer sensor because you get less IR for a given average exposure, i.e. if you boost one stop (green light peak light meter reading), and stop down one stop, you get more blue and less IR on the sensor.

Some light meters are heavy on the red sensitivity and do not show the gain as much on boosting, my Brother found a early light meter that seems to be from the late silent or early sound movie days, anyway it shows a larger change with boosting than the newer light meters that use silicon (like the RED ONE (tm) sensor) maybe because it has a filter in it for use with Ortho film to block the red light.

The use of xformers could be very helpfull to people shooting with RED ONE (tm) cameras since they have remarked that using a 80 series filter would cause them to need more light fixtures, this way you need the same or fewer fixtures, a little more to to a little less power, and get more blue light to reduce the sensor+compression noise.

The high K lamps have a shorter life, which makes you need to turn them off while setting up to "save the bulbs". If you have a low/high switch or relay on your booster you can run the lamps at lower voltage for setup, and boost while shooting or taking light readings, hence the foot switch. This can give a total bulb life that is longer since the lamps tend to be on more when not shooting than shooting. With the booster you can use heavy filament lamps that take rougher handeling than say photofloods or similar.

We did some tests on boosting florescent fixtures with solid state ballast to like 135v and did get some gain, maybe 1/3 stop. You don't want to burn out the ballast, but if the line voltage is low it seems you can use a variac to get the light level back up and a little more maybe.

This is not my idea, these xformers were standard equipment before quartz lamps.