Lumen Loss with Short Throw lens

[Ben Lawrence]

I have a projector with a Short Throw lens on it. It seems like I remember it being brighter when I had the standard lens mounted in a similarly lit room.
Is there a loss in Lumens associated with using a short throw lens compared to a "standard" lens?

 

[Rob Spence]

I have a projector with a Short Throw lens on it. It seems like I remember it being brighter when I had the standard lens mounted in a similarly lit room.
Is there a loss in Lumens associated with using a short throw lens compared to a "standard" lens?

Two things I can think of
1) lamps get dimmer over time
2) lenses do not all have the same light transmittal. There is an f stop value associated with a lens. The lower the number, the more light gets through. Low values are more expensive as they require more expensive glass.


Sent from my iPad HD

 

[Ben Lawrence]

Cool thanks for the response. I swapped out for the standard lens and the brightness was similar. The short throw lens was not cheap so doubting it has a significant light loss. It does create a bit more of a hot spot with rear projection though.