8mm Forum: LUMENS

This is topic LUMENS in forum 8mm Forum at 8mm Forum.

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Posted by Marty Pinkerman (Member # 1523) on April 10, 2009, 03:02 PM:

Does anyone know the lumens of an EFP 12V/100watt lamp?

Posted by Kevin Faulkner (Member # 6) on April 11, 2009, 12:34 PM:

I have checked various sites but cant find a definite answer for you. The reason is probably because it will depend on many things which are variables.
When used in a projector the size on the image, the lens, and supplied voltage are all things the manufacturers cant predict. All they can say is that the light output in terms of wattage is 100W.

Sorry I cant be more helpful.

Kev.

Posted by Marty Pinkerman (Member # 1523) on April 11, 2009, 08:07 PM:

Do you think these would work?

http://www.superbrightleds.com/specs/mr16_5mmLED.htm

Or how about one of these?

http://shop.ebay.com/items/?_nkw=mr16+led&_sacat=0&_trksid=p3286.m270.l1311&_odkw=MR16-W32&_osacat=0

Posted by Winbert Hutahaean (Member # 58) on April 12, 2009, 10:33 AM:

Based on comparation with my Infocus X1 (1000 lumens) at the same screen size, I believe 100w will be around 800 lumens.

But if you are thinking that the brighter is the better,... you are wrong. The best Video Projector for movie (only) is around 800 - 1200 lumens.

If you get higher than that then it is supposed to be a data projector (or a movie projector for a gigantic screen size, which is not for domestic use).

An High end VP is 1000 lumens.

cheers

Posted by John Whittle (Member # 22) on April 12, 2009, 11:19 AM:

Lumens are a good way to compare one lamp to another in their output, but the measurement is of little value in predicting screen brightness.

The SMPTE measurement (and standard) for screen brightness is foot-lamberts. This is a measurement of the light hitting the screen (not the reflection from the screen which would incorporate another variable screen gain). When you measure the light hitting the screen you take into account the shutter and condensing lens system in the projector. The measurement is made open gate.

When you compare a lamp in a video projector or slide projector which is putting light out 100 per cent of the time with a projector that is putting light out 60 percent of the time, you can see where a lumens comparison is of little use.

Where it is of value is comparing the same design lamp in a projector (such as ELH and EJL for example) where the lens reflector is the same or say a 1000 watt vs a 750 watt in the old style 16mm projectors.

One problem with using a 16mm lamp such as the EJL in an 8mm projector is the lamp reflector which is part of the lamp and the filament have been designed to cover the 16mm frame width (.380 inch) and as such a great deal of the "lumens" will be lost inside the lamp house when used in a Super8 projector. The EJL lamp is engineered to be 2 inches behind the aperture plate and provides max brightness across the frame at the point. It won't "focus" to a different point for the 8mm frame.

John

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