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Author
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Topic: An interesting observation
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David Pannell
Phenomenal Film Handler
Posts: 1072
From: Horsham, West Sussex, UK
Registered: Nov 2004
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posted January 23, 2008 06:50 AM
In my quest to achieve more light output from my three classic standard 8 projectors, I conducted a few experiments.
They are all designed to take a 750 watt A1/9 (DDB/DDW) lamp.
The Elmo E-80 has an f=1.4 @ 0.8in. lens.
The Elmo F-80 has a zoom lens @ 0.8 - 1.25 times, no f number.
The Ampro Futurist 8 has an f=1.6 @ 1in. lens.
NOW; With all screen illuminated frames adjusted to be the same size by adjusting distances between projectors and screen, the following was observed:
Brilliance
The Ampro was the brightest - no question.
Second brightest was the Elmo E-80.
Dullest was the Elmo F-80 with the zoom lens.
Heat
The coolest lamphouse was the F-80
Second coolest was the Ampro
Hottest was the E-80
These results were clearly related to cooling efficiency and relative sizes of the different lamphouses.
Next, I swapped the 2 Elmo lenses over. The Ampro was still the brightest, but both the Elmos were of similar brightness to each other, but duller than the E-80 with its original lens.
HERE'S THE INTERESTING BIT:
As the Elmo F-80 has the largest and coolest of the lamphouses, I decided to try it with a 1,000 watt A1/59 (DFD) lamp ![[Eek!]](eek.gif) and the f=1.4 lens, (the Ampro lens won't fit the Elmos).....I nearly had to put sunglasses on! It was absolutely dazzling! Even brighter than my Eumig S810D!
The temperature reached about the same as the Elmo E-80.
I certainly will not attempt to try the E-80 with the brighter lamp, as it has the smallest of the lamphouses, and I am very dubious about trying the Ampro too - not so much for the cooling, but due to the current carrying capacity of the lamp switch, which is a special rotary type, and probably difficult, if not impossible to replace.
I have to say that all these tests were subjective, without the use of lightmeters or electronic thermometers - though I do have these instruments - but they were not deemed necessary, as the results were abundantly obvious.
It does seem strange that the f 1.6 lens gave a brighter image than the f 1.4 in the earlier tests. Must be due to better reflector and condenser optics in the Ampro ![[Confused]](confused.gif)
Hmmmmm! INTERESTING!
--------------------
Dave.
Valves and celluloid - a great combination!
Early technology rules OK!
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