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STUART_H

Anyone use a Fresnal lens to increase screen size?

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I was looking for a cheapish solution to increase the size of my 17" monitor and have seen a 26" Fresnal screen which is placed in front of the monitor. Does anyone currently use such a device and if so how do they find the resultant picture? What degree of degredation in sharpness etc is experienced? I don't want to waste money if it is not worth it.Regards,Stuart Hyett


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Guest Lobaeux4

I have seen many guys here who use a Fresnal lens, even a couple of pics of cockpits linked from some of the cockpit part manufacturers websites. It sounds like a good idea, and something that I might look into as well.Lobaeux

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Guest MikePowell

Stuart,There is some information on Fresenel lenses on my website under scenery display/lens collimation. The links page has a list of sources if you want to price shop. I have not used a Fresnel lens, so can't give you a first hand opinion, but people who have posted about their experiences have been positive. You might take a look at Rick Lee's site http://www.rickleephoto.com/rlcoll.htm . There is also a paper on the Link simulator site about commercial uses of Fresnel based display systems. I think Rick Lee has a copy on his site as well. The most recent post here on using a Fresnel lens in a simpit was posted by Roland vanRoy. It's been a few weeks and the pictures may have been deleted by now, but I think Roland is your best source currently for first hand feedback on Fresnel based displays in simpits.Best of luck and keep us posted on how it works for your project.Mikewww.mikesflightdeck.comInfo for simpit builders.

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Guest Lobaeux4

Come to think about it, our C-130 sim here use to use fresnal lenses for it's outside views. In fact, I'm pretty sure they did, because you could sometimes see the sides if you will of the box the monitor would sit in. Now we've got a full panoramic view in the sim, so they don't have them anymore. It used to give a kind of shimmering view, but I think it'd more than offset the benefit. I read somewhere that it even gave a pseudo-3D look, but I may be mistaken. Gonna check out the site that Mike suggested.Lobaeux"just a posting fool today"

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Guest

I did some experiments with freshnell lenses. The one on the picture is a large freshnell stripped from an old projection TV. The picture quality is quite good, as long as you keep the magnification within reasonable limits. This can be tuned by adjusting the distance monitor screen to lens. When you make the distance too large, the edges become distorted, and you get some color abberations (red edges along lines). Also the distance of your head to the freshnell lens need to be tuned. http://forums.avsim.com/user_files/12220.jpghttp://forums.avsim.com/user_files/12221.jpghttp://forums.avsim.com/user_files/12222.jpgNote, the actual view is much better than the picture. It is quite difficult to make a good picture from a freshnell lens view. You can see some slight color abberations at the bottomPure flat screens (LCD or CRT) work better than conventional rounded CRT screens. (less distorsion at the edges). The reflections from ambient light can be reduced by building a box between lens and monitor.Freshnell lenses also create an effect of depth. If possible, only display scenery via the freshnell, and put the cockpit panel on a separate monitor w/o lens. The margins between multi-monitor setups can be eliminated when using one separate lens for each monitor. Cutting one big lens in half won't work: you need the lens center aligned with each monitor screen. The angles of the view can then be tuned to make the scenery just overlap. http://forums.avsim.com/user_files/12224.jpgFresnell lenses from old overhead projectors are normally too small, and have too coarse patterns. (you also have to split the two halves before you can use them for view enlargement. They can be used up to 14" monitors). The lenses from RC simulations have had good reviews from other cockpit builders, but are somewhat expensive. Be careful with the pattern side of the lens: It scratches easily. Roland

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Guest MikePowell

Hi, Roland,Nice pictures!Mikewww.mikesflightdeck.com

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Guest

Thanks Mike,Too bad I had to tear the whole thing down for the move. Now everything is boxed up waiting for the sea container. At least it gives me a good excuse to start learning some VB programming ;) Roland

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Guest MikePowell

I was wondering when you would have to do that. Hopefully your move will go smoothly and you'll be able to get things set up nicely. Do you have a place picked out, or will you be parking things in storage while you house hunt?Mikewww.mikesflightdeck.com

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Thanks to everyone for their input.I think I may give the fresnal a try for myself. One question Roland, is on the loss of sharpness. I know that you said it partly depends on the distance from the screen and that your picture does not do the actual view justice, but is there a noticable loss in sharpness / clarity especially when viewing guages?Thanks again to all,Regards,Stuart Hyett


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Guest Lobaeux4

Just received this email from Maxiaids.com about their 17-19" monitor lenses:The price of the magnifier is $39.95, the shipping for UPS ground service is$5.75. The total is $45.70. NY residents add applicable sales tax. thanks.Here's the description off their page at maxiaids.com:Makes your 14-15" monitor enlarged to about 20" with tthe help of this filter. Magnifiers approx 2x. Also available for 17-19" monitorsIs this the correct lens to go with, anyone?Lobaeux

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Thanks Mike, We'll settle in my childhood neighbourhood close to Schiphol Airport. Not a bad spot for flightsimmers I would say. Space is an issue, so I may have to re-design my platform so it fits in the attic. I've been thinking about a triangular setup, which could include heave, but first the interface side must be dealt with. Roland

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Guest

Sharpness will be worse on the edges of the screen, esp when using the conventional (rounded) CRT display at maximum magnification. The size of the lens should be bigger than the display. A "just fit" will make the edge distorsion also worse. I found the gauges look pretty good on my display. but as mentioned, it is more realistic to put them on a separate display and keep the lens for scenery only. (FS2002) You only need on extra cheap PCI video card and small extra display. Very simple to setup on single PC. Roland

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Guest Lobaeux4

I checked out the cockpit site, it's exactly what I want to do. I'm already trying to figure out how I can do it.As far as the fresnal lens goes, do you know of any U.S. distributors for the same type as RC Simulations has? I don't mind paying the price they want, but I can only imagine the postage back here to Arkansaw!Lobaeux

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