Can I eliminate the fresnel between the lamp and the lcd using the 5 inch psone lcd screen?
I want to put the 13 inch fresnel between lcd and objective.
I plan to place the 150 hqi at say 5 inches from the psone screen.
I want to put the 13 inch fresnel between lcd and objective.
I plan to place the 150 hqi at say 5 inches from the psone screen.
I wouldn't recommend "eliminating" it at all, the outside of your image will be much darker than the centre if you leave it out.
The fresnel shouldn't be that much extra work to put in and will give you a much better light evenness across your picture. If you can get a 220mm one then your light position will be fine at around 5 inches away from the screen anyway.
The fresnel shouldn't be that much extra work to put in and will give you a much better light evenness across your picture. If you can get a 220mm one then your light position will be fine at around 5 inches away from the screen anyway.
its possible
You could leave out the condensor fresnel if you supply the LCD with parallel light rays. A parabolic reflector would be one way to do that. (But such a reflector would probably cost more than a fresnel!)
You could actually do it with NO fresnels at all, if you used a huge elliptical reflector that focussed the light through the LCD and into the projection lens.
You could leave out the condensor fresnel if you supply the LCD with parallel light rays. A parabolic reflector would be one way to do that. (But such a reflector would probably cost more than a fresnel!)
You could actually do it with NO fresnels at all, if you used a huge elliptical reflector that focussed the light through the LCD and into the projection lens.
What could I use as a hude eliptical reflector?
Also would the objective not have to be as big as the round diameter of the lcd about 4.5 inches no? Or are you using the reflector would condense the beam to an even smaller point than the that?
Also would the objective not have to be as big as the round diameter of the lcd about 4.5 inches no? Or are you using the reflector would condense the beam to an even smaller point than the that?
huge elliptical reflector
I don't think anybody has tried it, but it should work by sending all the light rays to a small point in the center of the projection lens. So a large lens would not be necessary.
It would have to be bigger than the LCD. The size depends on the size of the LCD and the LCD to lens distance. You could make a precise drawing with rays going from the center of the lens, through the corners of the LCD, and then back to the edges of the reflector. That would show you how large to make the reflector.
The reflector surface should be polished aluminum, silver, mirror (glass with aluminum or silver coating), or maybe aluminized mylar. Those can all be >90% reflective. The shape must be a very good ellipse. This would be difficult to make!
I don't think anybody has tried it, but it should work by sending all the light rays to a small point in the center of the projection lens. So a large lens would not be necessary.
It would have to be bigger than the LCD. The size depends on the size of the LCD and the LCD to lens distance. You could make a precise drawing with rays going from the center of the lens, through the corners of the LCD, and then back to the edges of the reflector. That would show you how large to make the reflector.
The reflector surface should be polished aluminum, silver, mirror (glass with aluminum or silver coating), or maybe aluminized mylar. Those can all be >90% reflective. The shape must be a very good ellipse. This would be difficult to make!
- Status
- Not open for further replies.