| Jamez_Warner |
I've searched to death in here and google and cannot seem to find any good quality largish fresnels, will be using a monitor around 15" or less
I understand it'll need a focal length of around 300mm?
any help would be appreciated
James
PS. what's the advantage of split fresnels? |
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| [RPD]-Killer |
| Alan from Diylabs.org ships his new 15.5" fresnels worldwide... ;) |
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| Jamez_Warner |
| thanks - seems very expensive - are they that much better than the £1.99 ebay models? ( they have the right FL ) |
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| doughboy |
| If you dont like diylabs price, buy them here where they are even more expensive. Quality, large enough fresnels are not that cheap. |
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| Jamez_Warner |
ouch ! - please loose the attitude, I was only asking a reasonable question - what makes up the large price difference ? If that's something I cannot skimp on then so be it ! - my first projector just used two glass lenses from a stage light - a 1000W stage bulb and a LOT of forced cooling, the quality/brightness exceeded a commercial projector in a side by side comparison, allthough had the inevitiable yellow tint from the type of bulb
James |
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| bobharry |
| I don't see any bad attitude, but the page mags (the £1.99 ones your talking about) are only really good for that, magnifying pages, so yes the OHP quality fresnels are much better than them. If you want to get decent quality projection you will have to spend the money on a good fresnel. |
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| Jamez_Warner |
OK, would a fresnel from an old OHP work? ( is the FL ok for this application ? )
James |
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| bobharry |
| Yep the focal on an ohp fresnel is fine, but the fresnel might be warped, I haven't seen any warped ones in ohp's, but I think someone here said they can get warped. I don't think it will be big enough for a 15" panel, but anything under that will be fine. |
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| doughboy |
Now I have a bit of an attitude. You claimed you searched to death so I dont find your question reasonable. If you do a search for "fresnel" or "fresnel lens" you will find threads with "fresnel" info. Half the projects in here use a 12"x12" fresnel and lcd monitor, did you miss all of them? If its a problem of finding them in the UK, buy them from someone who will ship it to you. People keep joining this forum and just want everything handed to them. If you dont want to due the research, just buy plans from lumenlab.com.
Split Fresnel |
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| Jamez_Warner |
I've in fact been here longer than you doughboy, all I wanted to know was if there was any suppliers in the UK, if it's difficult i'll get hold of a projector lens from somewhere...
and yes I did look through all the fresnel search results and found no reference to UK suppliers....
James |
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| doughboy |
Heres a cookie for joining before me (Im not actually giving you the cookie). And if you've been here longer, Why are you asking questions that have been asked and answered?
Aslong as everything works out, you will be hard pressed to due better than alan's 15" fresnel. 12" fresnel are cheaper but you cant utilize all the monitor. |
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| Jamez_Warner |
I was just trying to show I hadn't just walked in and started firing off questions !
anyway a different tack then - i've just been offered a 5" LCD, are there any disadvantages to using such a small LCD? ( except for the screen door + resolution issues )
if so I could use a far smaller fresnel
James |
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| doughboy |
The active area of a fresnel needs to only be as big as the screen used, a little bigger if you dont split it. You can cut a big one down to size.
Smaller lcds tend to have lower contrast ratios, no vga input. Keep the picture from getting too big and screen door shouldnt be a problem. |
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