Okay, another two questions from the newb:
1) Using the focal length calculator II, in setting the range to the screen between 8ft and 20ft, I get LCD to ProLens values of 630mm to 540mm (respectively). How much objective lens travel do designers usually put in to achieve focus? Do people design for one throw distance or multiple throw distances?
2) I cannot find any fresnel lens for my collector that would work exactly on focusing to the projection lens. When compromising collector focal lengths, do you compromise with a larger focal length, or a smaller focal length then you need? (for instance, if the LCD to projection lens distance is 350mm, and the design is an unsplit design, would you choose a 317mm collector, or a 550mm collector, to place between the light and the lcd?)
As always, thanks for any help!
QUOTE (srinity @ Sep 3 2006, 09:16 PM) 
Okay, another two questions from the newb:
1) Using the focal length calculator II, in setting the range to the screen between 8ft and 20ft, I get LCD to ProLens values of 630mm to 540mm (respectively). How much objective lens travel do designers usually put in to achieve focus? Do people design for one throw distance or multiple throw distances?
2) I cannot find any fresnel lens for my collector that would work exactly on focusing to the projection lens. When compromising collector focal lengths, do you compromise with a larger focal length, or a smaller focal length then you need? (for instance, if the LCD to projection lens distance is 350mm, and the design is an unsplit design, would you choose a 317mm collector, or a 550mm collector, to place between the light and the lcd?)
As always, thanks for any help!
1) Using the focal length calculator II, in setting the range to the screen between 8ft and 20ft, I get LCD to ProLens values of 630mm to 540mm (respectively). How much objective lens travel do designers usually put in to achieve focus? Do people design for one throw distance or multiple throw distances?
2) I cannot find any fresnel lens for my collector that would work exactly on focusing to the projection lens. When compromising collector focal lengths, do you compromise with a larger focal length, or a smaller focal length then you need? (for instance, if the LCD to projection lens distance is 350mm, and the design is an unsplit design, would you choose a 317mm collector, or a 550mm collector, to place between the light and the lcd?)
As always, thanks for any help!
1) People say that you wanna leave ~2" of travel. Personally I'm just going to leave enough travel for the pro lens to go between all the way out and flush with the front of the box. The fresnels and stuff aren't perfect, and it's going to be hard to mount the lens perfectly, so you'd better plan for at least some adjustability...
2) You actually don't want the light to focus to a point on the projection lens. Most people make it so the light would be focused past the projection lens. So opt for the longer FL...
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