[imamosher]

When would you use this and what exactly does it do?

[Gary Lightfoot]

Do you mean ND2?

If so, and ND filter is a Neutral Density filter which will reduce the light output of the pj without altering the colour balance by an appreciable amount. They are usually used if the image is too bright and you want something closer to the reflectance levels you get at a commercial theater (which are approximately a third as bright as direct view TVs). An ND2 reduces the lumen output by 50% and an ND4 will reduce the lumen output by 75%. Visually, and ND4 gives the impression of almost 50% reduced brightness as our eyesight isn't linear (82% reduction in lumens is perceived as a 50% drop in brightness).

Gary

[imamosher]

hi gary, thanks thats really helpful

I have a light coloured room and there isnt anything i can do to dull it at all. There is a lot of light refelecting from the walls and wondered if this would help at all to reduce that without affecting the picture at all?