fresnel/triplet question

Gizmotech · 27th March 2005, 12:13 PM

where abouts is the triplet lens mounted? is it the focal length from the collimator fresnel lens or the focal length from LCD to the Triplet Lens??

Also the size of the triplet lens (in diameter) and magnification, what difference will it make to the projected image???

Rox · 27th March 2005, 05:56 PM

the triplet specs depend on varios factors, the required image size.. the fov needed... you need first a desired triplet and then look what fresnell suits best for this triplet.
roughly speaking (its well said?) you need a field fresnell with a larger focal than the projection lens. It could be 3 cm larger or 30cm larger depends on various things;

your throw, lcd size, triplet diameter...

mostly, a larger diameter triplet will give you more light and a sharper image. thats because every small part on the triplet will do more specific work than smaller diameter lens. Thats hard to xplain on a diferent language than your mother tounge

dj_holmes · 27th March 2005, 10:25 PM

english is my third language. but i think i did o.k.
if you look at sites that sell diy goods it will normally said, designed for 15" or 7".. its the BEST way for a beginner to find his match... trust me. good luck

27th March 2005, 12:13 PM	#1
Gizmotech diyAudio Member Join Date: Mar 2005	fresnel/triplet question where abouts is the triplet lens mounted? is it the focal length from the collimator fresnel lens or the focal length from LCD to the Triplet Lens?? Also the size of the triplet lens (in diameter) and magnification, what difference will it make to the projected image???

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27th March 2005, 05:56 PM	#2
Rox diyAudio Member Join Date: Jul 2004 Location: ?	the triplet specs depend on varios factors, the required image size.. the fov needed... you need first a desired triplet and then look what fresnell suits best for this triplet. roughly speaking (its well said?) you need a field fresnell with a larger focal than the projection lens. It could be 3 cm larger or 30cm larger depends on various things; your throw, lcd size, triplet diameter... mostly, a larger diameter triplet will give you more light and a sharper image. thats because every small part on the triplet will do more specific work than smaller diameter lens. Thats hard to xplain on a diferent language than your mother tounge

27th March 2005, 10:25 PM	#3
dj_holmes diyAudio Member Join Date: Nov 2004 Location: london	english is my third language. but i think i did o.k. if you look at sites that sell diy goods it will normally said, designed for 15" or 7".. its the BEST way for a beginner to find his match... trust me. good luck

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