P3D Re: Halogen bulbs for projectors

[dalia miller <ddd@xxxxxxxxxxxx>]

At 02:39 PM 2/17/00 -0700, you wrote:
>Dalia wrote:
>
>>All the above named projectors can use halogen bulbs that 
>>provide a little more lumens (about 10%) and a much longer 
>>life than the CZX bulbs...

George wrote:
>My measurements showed that the halogen bulbs actually
>resulted in less lumens in both my 116 and 716 stereo
>projectors.  The difference was enough to convince me
>to stick with the original CZX bulbs.  Tom Hubin gave
>an explanation relating to the size of the bulb filament
>and the condenser lenses in these projectors.

Dalia wrote:
George, it might be interesting to see how you tested.  Let us know.  I
didn't do any scientific testing on the bulbs output because I just don't
have the knowledge nor the equipment.   I'm just reporting what the bulb is
rated for.  The 500w halogen bulb has 13,000 lumens; incandescent has
11,000 lumens.  The 750w halogen bulb has 20,000 lumens as opposed to the
incandescent's 18,000.

  I did do some very primitive testing a while ago with a Stereomatic 500
after I changed out the mirrors (didn't change the condensors) and replaced
the polarizers in each projector.  We measured the amount of light that
bounced off the screen with one of Andrew's fancy fancy light meters - and
the halogen bulbs produced a slightly brighter image.  It was not
appreciably brighter and I can't remember how much more candle power was
detected. 

My conclusion at that time was:  the halogen is only slightly brighter but
the bulb's  longevity made the bulbs much more desirable.  Please note that
I didn't test the bulb's longevity myself, we used the specs for the bulb.