[rambd]

Would someone be kind enough to explain to me was this means,I,m new to this arena of projection....what attributes hot spotting? How do you avoid it? Is it cuased by the projector or screen itself thanks

 

[Andrew Low]

Hot spotting & colour shift are usually mentioned in the same breath -- so I'll describe both.


Hot spotting: Avia has a test pattern for this. It basically means that the center of your screen is brighter than the edges. If you were to use a mirror as a screen you'd have the worst "hot spot" possible. Higher gain screens have more hot-spotting than lower gain screens. Most casual observers won't notice this effect even on the Draper M2500 screens which are about 2.3 gain. The degree of hot-spotting depends on how bright your projector is.


Colour shift: (forgive the spelling, I'm Canadian) This is an emphasis on blue on one side of the screen and red on the other. Corresponding directly to the 3 CRT tubes. If you are using a single lens projector you won't have this issue. The higher gain screens also show more colour shift in general. Even on my 1.3 gain screen I notice some colour shift. Careful calibration / setup can hide most of it -- but again, part of it is the nature of the technology.


Roo