F0.8 fisheye

[SourceChild]

Hey Peter,

My post was actually two separate statements.

The mirror was one.
The example I've done a 0.8 was the other.

Something else you can try would be a different projection screen medium. Part of the reason the image looks perceptibly darker to the edges is that your eyes are not directly on axis with the lens of the projector. Some screens account for this and others do not. Typically the ones that do have characteristics similar to road signs where no matter where you're shooting from, the image always seems to reflect back toward you.

In your case, try using a different screen medium to see if the brightness falloff goes down. Also, if you have visual distortion, use the spherical correction tools in the Mix windows.

[samsc]

Hey Peter,
Something else you can try would be a different projection screen medium. Part of the reason the image looks perceptibly darker to the edges is that your eyes are not directly on axis with the lens of the projector. Some screens account for this and others do not. Typically the ones that do have characteristics similar to road signs where no matter where you're shooting from, the image always seems to reflect back toward you.

perceptibly darker to the edges

this is not an explanation for this-

this effect is fundamental to the nature of projection coupled with reflection of light off diffuse surfaces-

projection surfaces dont come close to ever giving a perfect diffuse reflection of a surface- with even reflected light in all directions-

this is a very complex subject - and nothing to do with projectors themselves and all about material properties.

road signs are a red herring - they would make a terrible projection surface- - why dont you try one?
then try a piece of white laser printer paper?
which one makes the best surface?

http://en.wikipedia.org/wiki/Diffuse_reflection
http://en.wikipedia.org/wiki/Specular_reflection

[samsc]

In your case, try using a different screen medium to see if the brightness falloff goes down. Also, if you have visual distortion, use the spherical correction tools in the Mix windows.

what do you mean?

brightness falloff is not related to "visual distortion" and nothing to do with 'spherical correction'.

there is a reasonably competant explanation of some of these issues here:

http://www.projectorcentral.com/proj...reens_gain.htm

high gain screens are likely to make very poor surfaces for doing edge blends.
diffuse surfaces which reflect light more evenly depending on angle of incidence are likely to be much better.

Thus seating can be placed in a wide viewing angle relative to the screen and all seats will afford a similar viewing experience regardless of the angle of view. With a high gain screen the brightness of the image increases to those seated in the center, and diminishes for those seated at the outside.

so particularily in a theatrical environment where a wide viewing angle is required - high gain screens are poor choices.