How to optimize life of photoflood bulbs

aristotle wrote:
I need to take 2500-3000 digital photographs of antiques using 250
watt blue BCA photoflood lights. Is there anyway to extend the life
of these bulbs beyond the 3 hour life expectancy. Will it help to use
a dimmer to reduce power between changing art objects or turn off the
bulbs between object changes.

I might add that dimming will change the colour output.

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math

aristotle wrote:
I need to take 2500-3000 digital photographs of antiques using 250
watt blue BCA photoflood lights. Is there anyway to extend the life
of these bulbs beyond the 3 hour life expectancy. Will it help to use
a dimmer to reduce power between changing art objects or turn off the
bulbs between object changes.

I might add that dimming will change the colour output.

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math

In message ,
Bob Williams wrote:

Using a dimmer instead of turning the lights on and off may give you a
slight (10-15%) increase in lifetime but hardly worth the trouble.
As Crownfield indicated, your camera's White Balance may work with
regular incandescent lights just fine.

Possibly better, because most digital cameras are least sensitive in the
red channel, and the warm light increases the signal-to-noise ratio in
the red channel (which is usually higher than the other channels in
daylight exposure).
--


John P Sheehy

In message ,
Bob Williams wrote:

Using a dimmer instead of turning the lights on and off may give you a
slight (10-15%) increase in lifetime but hardly worth the trouble.
As Crownfield indicated, your camera's White Balance may work with
regular incandescent lights just fine.

Possibly better, because most digital cameras are least sensitive in the
red channel, and the warm light increases the signal-to-noise ratio in
the red channel (which is usually higher than the other channels in
daylight exposure).
--


John P Sheehy

In message ,
"Joseph Meehan" wrote:

I might add that dimming will change the colour output.

All the better. Most digital camera's CFAs favor warm light.
--


John P Sheehy

In message ,
"Joseph Meehan" wrote:

I might add that dimming will change the colour output.

All the better. Most digital camera's CFAs favor warm light.
--


John P Sheehy

In message ,
"Joseph Meehan" wrote:

I might add that dimming will change the colour output.

All the better. Most digital camera's CFAs favor warm light.
--


John P Sheehy

wrote:
In message ,
"Joseph Meehan" wrote:

I might add that dimming will change the colour output.

All the better. Most digital camera's CFAs favor warm light.


John P Sheehy


But it could be a problem if the OP wanted to match some sunlight coming
in a window in the background.

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math

wrote:
In message ,
"Joseph Meehan" wrote:

I might add that dimming will change the colour output.

All the better. Most digital camera's CFAs favor warm light.


John P Sheehy


But it could be a problem if the OP wanted to match some sunlight coming
in a window in the background.

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math

On 24 Nov 2004 20:28:19 -0800, (aristotle)
wrote:

I need to take 2500-3000 digital photographs of antiques using 250
watt blue BCA photoflood lights. Is there anyway to extend the life
of these bulbs beyond the 3 hour life expectancy. Will it help to use
a dimmer to reduce power between changing art objects or turn off the
bulbs between object changes.

I assume by "optimize" you mean maximize. The answer is yes.

You probably have noticed that most incandescent bulbs fail during
power up. This is because the filament flexes violently, and breaks,
during the rapid transition from cold to hot.

If you make use of a dimmer you will extend the life of the bulb
dramatically because the filament temperature will rise slowly
(relatively speaking). But, spend a few bucks and get a solid state
dimmer (not the rheostat types). Solid state dimmers use a
zero-crossing thyristor to control the power applied to the bulb.
This will reduce thermally-induced filament stress and extend bulb
life.

As an example, a number of years back, we had a ornamental lighthouse
on our lawn. The 60W bulb in it would flash every four seconds. We
would get a couple of months max before the bulb blew. I replaced the
mechanical flasher, with a thyristor-based flasher that I built. The
bulb was still flashing after 4 years of 24/7 operation. Might have
still been going if the lighthouse hadn't been vandalised.

Regards.