Has anyone tried the 200mm or the 550 mm fl hires fresnals from 3dlabs with success?
Did it give you a better clearer pitcure?
I am just starting this project and I came across those there and didn't hear about anyone using those yet.
Thanks for any input.
Scott
Did it give you a better clearer pitcure?
I am just starting this project and I came across those there and didn't hear about anyone using those yet.
Thanks for any input.
Scott
3dlens.com fresnel
I am using the 3dlens.com 550 mm fl fresnel, and it works great: Very fine pitch, so you can put it pretty close to the LCD surface if needed. I have used it in both split and unsplit designs. In a split design, the distortion it adds is pretty much invisible.
The best focal length for your field fresnel is determined by the distance your projector will have between the LCD and the projection lens. If you are using a 290-330 mm fl triplet, then the 330 mm fresnel would be the best match. If you are using a 450-500 mm fl long-throw projection lens, then you need to get the 550 mm fl fresnel.
The reason for selecting the field fresnel focal length to be a bit greater than the projection lens fl, is so you can get all of the light directed into the projection lens. It is possible to use a poorly-matched field fresnel by playing with the lamp to condensor fresnel distance, but it doesn't work as well as getting the right fresnels to begin with.
If you do buy from them, you might want to avoid the "super fast" shipping option. I used the normal airmail option and received my fresnel in less than 1 week.
I am using the 3dlens.com 550 mm fl fresnel, and it works great: Very fine pitch, so you can put it pretty close to the LCD surface if needed. I have used it in both split and unsplit designs. In a split design, the distortion it adds is pretty much invisible.
The best focal length for your field fresnel is determined by the distance your projector will have between the LCD and the projection lens. If you are using a 290-330 mm fl triplet, then the 330 mm fresnel would be the best match. If you are using a 450-500 mm fl long-throw projection lens, then you need to get the 550 mm fl fresnel.
The reason for selecting the field fresnel focal length to be a bit greater than the projection lens fl, is so you can get all of the light directed into the projection lens. It is possible to use a poorly-matched field fresnel by playing with the lamp to condensor fresnel distance, but it doesn't work as well as getting the right fresnels to begin with.
If you do buy from them, you might want to avoid the "super fast" shipping option. I used the normal airmail option and received my fresnel in less than 1 week.
So then... with the 550mm fresnel is the problem finally solved with using the DIYPC 135mm triplet and a 15" LCD?
That's kinda what I am wondering. I want to do a 15" split design and be able to put my projector approx 12' away from the wall so it sits behind the viewers. So I want a narrower focus width and end up with a 90-100" projection
I also want to build this as a verticle projector to limit the foot print it takes and make it more esthetically pleasing.
I also want to build this as a verticle projector to limit the foot print it takes and make it more esthetically pleasing.
I'm guessing you will have more like a 120" screen. Using a 450fl 135mm lens and a 550mm fl fresnel with a 15" screen.
You have to match the projection lens too. It's not all about the fresnel lens. By getting a projection lens with a longer focal length, you generally place the lens further away from the LCD. A little trig will tell you that the further away the lens is from the LCD, the smaller the FOV you need.
Additionally, you need a fresnel lens with a longer focal length to match. Until 3DLens came out with the 550mm, there weren't that many options for long throw. I recall a 630mm someplace and a 730mm (ish).
Additionally, you need a fresnel lens with a longer focal length to match. Until 3DLens came out with the 550mm, there weren't that many options for long throw. I recall a 630mm someplace and a 730mm (ish).
that's what I am doing
>15" split design ... projector approx 12' away from the wall ... 90-100" projection
That's exactly how I am using the 550 mm fl fresnel right now: I have an 18" fl opaque projector lens (5" diameter) and a 15" XGA LCD. I get about a 95" image that is very watchable in a dim room. I have a vertical light path that bounces off a first-surface mirror before the projection lens. I put the projector on a counter top at the back of the room, so the lens is perpendicular to the center of my painted-wall screen. (No keystone distortion)
>15" split design ... projector approx 12' away from the wall ... 90-100" projection
That's exactly how I am using the 550 mm fl fresnel right now: I have an 18" fl opaque projector lens (5" diameter) and a 15" XGA LCD. I get about a 95" image that is very watchable in a dim room. I have a vertical light path that bounces off a first-surface mirror before the projection lens. I put the projector on a counter top at the back of the room, so the lens is perpendicular to the center of my painted-wall screen. (No keystone distortion)
- Status
- Not open for further replies.