so I got the formula for the projector diagnol size from the diy lcd projector company
but how do I find the distance to place the lamp from teh fresnel, or the fresenl to the projector lense?
but how do I find the distance to place the lamp from teh fresnel, or the fresenl to the projector lense?
bokinator said:
Those distances are based on the focal lengths of your fresnels. ie: A 320 mm back fresnel will be ~ 320 mm away from the bulb. A 450 mm Front Fresnel will be ~450 mm from the projector lens. They wont always be at the exact focal length but usually close.
Zaner21
just a couple more quick questions.
you mentioned that the focal length are never exact, so does this involve trial and error by placing the fresnel lense closer or further away from the lamp, or would the specified focal length do the job.
And are there any specific calculations needed to pick the right fresnel lense?
or would a 330mmfront and 330mm rear do the job.
and why do I see peole place the smaller focal lengh lense closer to the lamp instead of the other side of the lcd.?
also, where are some good places to order fresnels for cheap and quality
you mentioned that the focal length are never exact, so does this involve trial and error by placing the fresnel lense closer or further away from the lamp, or would the specified focal length do the job.
And are there any specific calculations needed to pick the right fresnel lense?
or would a 330mmfront and 330mm rear do the job.
and why do I see peole place the smaller focal lengh lense closer to the lamp instead of the other side of the lcd.?
also, where are some good places to order fresnels for cheap and quality
I’m still in the gathering stage so I can’t speak from experience but I’ll try my best to answer your questions based on what I have learned from these forums over the years.
Yes, trial and error. If you can setup some kind of test bench to figure out all of your distances before you actually built an enclosure you will be better off. Talk to member Guy Grotke for more info on a test bench.
No special calculations, just need to know the focal length of your projector lens.
Do the job, yes. Do the best job, I don’t know.
Apparently you get a brighter image the closer the fresnel is to the lamp so the shorter the focal length the closer to the lamp you can get. You want to try and match the front fresnel to the same focal length as your projector lens.
Sorry, I don’t have any links. Look around the threads. I think one is called 3Dlens or another is diy projector company or lumenlabs.
Zaner21
Yes, trial and error. If you can setup some kind of test bench to figure out all of your distances before you actually built an enclosure you will be better off. Talk to member Guy Grotke for more info on a test bench.
No special calculations, just need to know the focal length of your projector lens.
Do the job, yes. Do the best job, I don’t know.
Apparently you get a brighter image the closer the fresnel is to the lamp so the shorter the focal length the closer to the lamp you can get. You want to try and match the front fresnel to the same focal length as your projector lens.
Sorry, I don’t have any links. Look around the threads. I think one is called 3Dlens or another is diy projector company or lumenlabs.
Zaner21
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