Printable View
Hi,
Are there other solutions besides using a frame with a black border or by creating a greater distance with 1.2 lens to minimize this effect?
I'm told that with the 0.8 we would always get this effect and that we will create a hotspot even on a quality screen.
Thanks!
Try using a mirror and a 1.2 lens. It might be a big mirror but it should work. Actually, I have a client with 3 10,000 lumen projectors rear projecting and edge-blending with 0.8 lenses and it actually works just fine.
The show goes on tour. So getting the mirror setup will be too difficult i think. Meaning it will be too time consumming to get the angle of the mirror in position. Or is there an easy solution?
10K projectors are out of budget.
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.
with multiple projectors on a surface - noone can give advice to determine whether something specific to a show will or will not work.Quote:
Originally Posted by Peter
expectations - equipment, projection surfaces, projector position and required results are all impossible to quantify.
the closer you look - there are no easy solutions with this type of projection.
you have to test and find something adequate for your needs.
touring these shows opens up an entirely different set of difficult problems.
Quote:
Originally Posted by SourceChild
this is not an explanation for this-Quote:
perceptibly darker to the edges
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
what do you mean?Quote:
Originally Posted by SourceChild
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.
so particularily in a theatrical environment where a wide viewing angle is required - high gain screens are poor choices.Quote:
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.
its not the projector and the lens - which make this stuff work or not work - its the projection layout - the screen positions and distances, and other factors like screen type.Quote:
Originally Posted by SourceChild
also rear projection is a completely different problem to front projection.
i also think peter is talking about front projection?
rear projection problem is a material transparency and refraction problem.
front projection is a diffuse surface reflection problem.
they are totally different.
I think the basic point is to try different things in different ways from lenses to screen medium, placement, etc.
Obviously though the more extreme the idea the greater likelihood it won't work in the long run and ultimately become a liability if it pushes too many limits.