ok so i get everything else but im having a hard time wraping my mind around the focal lenth and FOV and all the terminolagy of lenses. im gunna use the ushio retro UHI-S400DD USHIO bulb
and a 15" lcd now i havent bought the lcd yet so i dont know exactly what it will be diagnally and i havent bought fresnels yet iether. ill need the projector about 15ft from my screen also ... im just looking for some suggestions i saw this in a diff thread http://www.surplusshed.com/pages/item/l3297.html that seems to be a great price ... but i just dont wanna buy something i cant use ...
anyhelp would be great.
and a 15" lcd now i havent bought the lcd yet so i dont know exactly what it will be diagnally and i havent bought fresnels yet iether. ill need the projector about 15ft from my screen also ... im just looking for some suggestions i saw this in a diff thread http://www.surplusshed.com/pages/item/l3297.html that seems to be a great price ... but i just dont wanna buy something i cant use ...
anyhelp would be great.
There's really no way you're gong to get the projector 15' away.
With the "typical setup, 220 + 330fl frresnels and 80 mm triplett , the image would be 15' diagonal .
With a Pro LL Triplet it would be a little better , about 10' diagonal. But of course the Pro lens isn't here yet. 😉
With the "typical setup, 220 + 330fl frresnels and 80 mm triplett , the image would be 15' diagonal .
With a Pro LL Triplet it would be a little better , about 10' diagonal. But of course the Pro lens isn't here yet. 😉
well my projector is 15ft away right now ..... useing a OHP and a sharp qa1800 and iv got a really good image the only reason i want to build a box is to get it brighter ... and to control light leakage
another lens
Coated air spaced glass doublet objective lens, 80mm clear diameter by 900mm focal length. Plastic mount with O.D. of 95mm and front lip to butt against a tube up to about 100mm O.D.
any thoughts on that lens ? i can get for a decent price
Coated air spaced glass doublet objective lens, 80mm clear diameter by 900mm focal length. Plastic mount with O.D. of 95mm and front lip to butt against a tube up to about 100mm O.D.
any thoughts on that lens ? i can get for a decent price
image size & throw distance
You are comparing a 15" LCD projector with your sharp qa1800 LCD projector. That is why the image sizes are so far off. For a normal size (ie. 90-100") image, a 15" LCD projector with a 15' throw distance needs a projection lens with a focal length of around 22". That is the lens used on some of the Beselar opaque projectors (most are 18"). You can buy one of them for about $100.
If you can move your projector closer to the screen (132 to 140"), then you could use an 18" opaque projector lens. Much easier to find! Also much easier to use, since the 550 mm fl fresnel from 3dlens.com matches the LCD-to-lens distance perfectly.
A 900 mm fl lens will be very difficult to use. From 15' with a 15" LCD, you would get an 80" image. I don't know where you would find a field fresnel to match it.
Why not just stick with the LCD and optics you have now? Then you just need to build a box with a MH lamp & ballast. You can get a Ushio 400 Watt Retrofit lamp for $38 and a cheap ballast for $29, if they still have them. Look for the threads using the search button.
You are comparing a 15" LCD projector with your sharp qa1800 LCD projector. That is why the image sizes are so far off. For a normal size (ie. 90-100") image, a 15" LCD projector with a 15' throw distance needs a projection lens with a focal length of around 22". That is the lens used on some of the Beselar opaque projectors (most are 18"). You can buy one of them for about $100.
If you can move your projector closer to the screen (132 to 140"), then you could use an 18" opaque projector lens. Much easier to find! Also much easier to use, since the 550 mm fl fresnel from 3dlens.com matches the LCD-to-lens distance perfectly.
A 900 mm fl lens will be very difficult to use. From 15' with a 15" LCD, you would get an 80" image. I don't know where you would find a field fresnel to match it.
Why not just stick with the LCD and optics you have now? Then you just need to build a box with a MH lamp & ballast. You can get a Ushio 400 Watt Retrofit lamp for $38 and a cheap ballast for $29, if they still have them. Look for the threads using the search button.
iv got that ballast of ebay for the $28 and im gunna get the ushio
i am useing the sharp 1800 on the OHP now and getting 120" diagnal 15 ft away .. but low contrast ... and not bright enough
i will be getting a " free" 17" lcd .... and i may use that if it strips well ... if not ill be looking for a 15" i do like the sharp ... i just dont wanna strip the panel to use it in a box... cuz i will resell it if i get the 15" lcd and the box built. the res on the 1800 is 800x600 but i can really tell the diff on the contrast.... so i dunno yet i just cant decide witch way to jump ....that and im in a apartment ... so box building will be a pain ... lol
i am useing the sharp 1800 on the OHP now and getting 120" diagnal 15 ft away .. but low contrast ... and not bright enough
i will be getting a " free" 17" lcd .... and i may use that if it strips well ... if not ill be looking for a 15" i do like the sharp ... i just dont wanna strip the panel to use it in a box... cuz i will resell it if i get the 15" lcd and the box built. the res on the 1800 is 800x600 but i can really tell the diff on the contrast.... so i dunno yet i just cant decide witch way to jump ....that and im in a apartment ... so box building will be a pain ... lol
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