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Thread: RGB spatial filter lens options

  1. #1
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    Default RGB spatial filter lens options

    Any comments on if these lens like work for a spacial filter for full color rgb or any recommendation of what I should be looking for. Thanks. http://www.edmundoptics.com/optics/o...c-lenses/1749/
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    Should work fine. Triplets are better but try those first. If you are aggressive in the pinhole it won't matter as it shaves off the outside that is not totally in focus. You lose a bit of power but the result is spectacular. Jors does this with no issue. I've been burning my pinholes in place by letting the beam burn through a guitar pick or tape. I figure it it is strong enough to burn through that is the power core. Damn be to the rest of the beam.

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    Another optical consideration is that dispersion (differential focusing effect for each color) is inversely related to focal length. If you have the room, no matter what type of lenses you choose, the longer the focal lengths, the better the spatial filter will work. Alignment and spacing ease as well as stability will improve with the square of the focal lengths.

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    Quote Originally Posted by planters View Post
    Another optical consideration is that dispersion (differential focusing effect for each color) is inversely related to focal length. If you have the room, no matter what type of lenses you choose, the longer the focal lengths, the better the spatial filter will work. Alignment and spacing ease as well as stability will improve with the square of the focal lengths.
    Thanks for the info, though not what I wanted to hear. .
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    Thanks for the info, though not what I wanted to hear. .
    Don't sweat it. If you choose to go with multi-element lenses, the chromatic aberration is so small that it will pail compared to other real life limitations in any projector application. The other effects of longer focal lengths will be more important and if you work with two spatial filters side by side, differing only in their focal lengths, you will quickly notice how much EASIER it is to get a good result with the longer. But with care both will work well.

  6. #6
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    Quote Originally Posted by planters View Post
    Don't sweat it. If you choose to go with multi-element lenses, the chromatic aberration is so small that it will pail compared to other real life limitations in any projector application. The other effects of longer focal lengths will be more important and if you work with two spatial filters side by side, differing only in their focal lengths, you will quickly notice how much EASIER it is to get a good result with the longer. But with care both will work well.
    Thanks again I have noticed it is easier to find and work the pinpoint with longer FL, any thoughts on using mixed FL does it benifit to start with a longer or shorter in comparison to using equal FL over the same distance
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  7. #7
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    It is probably easier to start with a longer FL lens as the required position of the pin hole depends on this and not the following lens. But, usually the FL order is dependent on what the magnification or de-magnification ratio you wish to produce in order to optimize scanner mirror filling.

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    Quote Originally Posted by planters View Post
    It is probably easier to start with a longer FL lens as the required position of the pin hole depends on this and not the following lens. But, usually the FL order is dependent on what the magnification or de-magnification ratio you wish to produce in order to optimize scanner mirror filling.
    Here here to that. I shoot for 2x. And do 50/100mm. But get much easier results from 100/200mm
    i found I can fold the path with a mirror and that makes the path work out easier for layout. The single rgb spatial is a pain. Do individuals if you have room.

  9. #9
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    The single rgb spatial is a pain. Do individuals if you have room.
    That is exactly how I do it. I'm happy with this approach. Folding has another benefit. It allow you to use the controls on the optical mounts to conveniently position the beam as it moves through the optics without having to loosen or shim a smaller, non folded optical train. Been both places and done both ways. I kept only one tee shirt.

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