Archived

This topic is now archived and is closed to further replies.

Guest stevelep

Fresnel's Lens VS Projectors

Recommended Posts

Hello,To have more realism in my cockpit, I would like to have a largefront view .Video projectors are still expensive especially if you want 1024x740resolution.I heard about Fresnel Lens technic.What's your experience ?Here's some questions:- What are the best resolution for projectors considering I'm not Trump's son !!! ? :-cool- Is SVGA enough for FS ?- What about lumens need lots or not ?- What about Fresnel Lens, what the price, the dimentions, where to buy it ? Do you know webshop who sell it ?Thank's for your adviceBOBPS: Builders who have still a projector or Fresnel optics Tell me your experiences ...

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

darn good questioncuriously waiting for a reply miselfsubscribe to this topic to ... *check*

Share this post


Link to post
Share on other sites

BOB,This topic came up not long ago. Scan the past few weeks. Pookie posted his URL with some pictures of his Fresnel set up. There is some background info on my site along with a list of suppliers on the links page. You might also take a look at Delta Flight's site. They are using three large TV monitors, apparently to good effect. Projection systems are nice, but depending on your circumstances (space, money, etc.) may not be your best choice.Mikewww.mikesflightdeck.com

Share this post


Link to post
Share on other sites

Here's my experience:I went from using a single LCD monitor (17") with a Frensel Lens to a 1024x768 projector (rear projected onto the front of the cockpit (~1 metre wide) and I was very dissapointed.Yeah, the image was much bigger but even with a 1024 projector the pixels are way too big - each one is clearly visible. You need to crank the anti-aliasing on the video card up to max to make it barely useable - i.e. to get jaggies and shimmers down to a useable level. Watch the framerate crash.The problem is that you're sitting about a meter away from the image. (On rear projection anyway).You might have more luck sitting further away but then you'll need to project bigger.I also tried out a 800x600 projector and this really was far too poor to use.Having lived with it for a year, I've now gone for a Matrox Parhelia and the BugEye display unit (three LCD displays with Fresnel lenses). The resolution can run up to 3096x768 in FS9 covering the same area as the projector. The other consideration is depth perception. Because the Fresnel lenses are colimating the light you get a real sense of looking outside the cockpit. With the rear projection you're looking at a flat image a metre infront of you. Your brain isn't really fooled.For me, I got a better sense of emmersion using the 17" monitor and lens that with projected display. With what I know now I'd pick a 21" monitor with a nice big fresnel lens over a projector everytime. Much cheaper these days too.Another thing to take into account is that you can't use fresnel lenses on a 2-man cockpit unless you give each person their own independent display because of the viewing angles.To sum up then... If you're going to use projection I would say 1024x768 is minimum, but with the new graphics cards that do multiple monitor spanning, projection may not be the best solution these day. Consider 1, 2 or 3 monitors or lcd panels with fresnel lenses. If you position the lenses right you can eliminate the borders between the displays. Don't know how hard this is to get right though. That's why I went for the pre-built BugEye solution (Well, that and the GBP/USD exchange rate at the moment!). It could be done cheaper if you make something similar yourself and use monitors instead of LCD planels.Of course it all depends on your budget and personal taste. I would suggest you borrow a projector before buying to test it out and see if you like the results.Paul

Share this post


Link to post
Share on other sites

I think this sums it up pretty well. One thing with fresnels is that those fuzz the image a bit so the pixels are not that visible and lack of antialias doesnt bother you. Remember that you can have even a lower resolution for the outside visual since your instruments are not shown from there. The instruments need to be exact and sharp, but if those are in another monitor on your panel, or mechanical versions or such, those are not relevant when you consider your outside view resolution. Even 640x480 can be tolerable, especially for IFR when you dont need to see the scenery that much.I have to agree with the collimation point - our collimated mirror does give a very very nice feeling of depth. It helps the feeling of immersion a lot.Tuomas

Share this post


Link to post
Share on other sites

Well Based on my experience with projector that I bought for $1K at University of Maryland media center. Projector seem work quite well with FS9 version. But not with FS2KX version, I guess it's because it has a better resoultion, better FPS and umm... I don't know, I am not the expert. When I tested my projector along with 17" monitor using VGA spilter I could see that projector seem to be a little off compared from my monitor. For example, at full screen, when I want to hit alt I would have menu bar appear on the top of the screen. As far it showed on the monitor but not projector. I changed the resoultion from FS2X or tried to change different type of video card in order to display same screen as monitor yet, there is nothing I can do. For now I am continuing using projector until I get sufficent money to get Maxtor Parpella 3 VGA ports just like Mike at Deltaflight instead of purchasing another thousand dollar for a better projector. You may want to consider doing same.

Share this post


Link to post
Share on other sites

PaulThank's for your interesting and complete reply.:-outtaI'm building a single pilot cockpit ... soFresnel lens with monitor seems to be a good ideaHave anybody an idea where I can buy such Fresnel Lense(in Europe) (websites, factory ...) BOB

Share this post


Link to post
Share on other sites

hi bob , for a lens try RC Simulations Bristol uk, i bought mine last year from them its about 25 inches diagonal, 21in across by 17 in high, about 8 in from a 21 inch monitor slightly blue tint ,its not bad i think its better than the normal screen and it was about

Share this post


Link to post
Share on other sites

Interesting.I use a preowned projector I got off eBay for $400. Resolution is 1024x768, and it projects from a bookcase over my shoulder to a screen about three feet in front of me. The resulting image is about 50" wide. I love flying with it as the outside display.However, I don't see individual pixels as others have. Perhaps I'm just getting old . OTOH, I use another projector just like it (again, about $400 used) to view movies in a darkened room on a screen about 60" wide, and it looks terrific to me and visitors.Both preowned projectors came with less than 200 hours on the 2000 hour bulb. Both were owned by offices that upgraded to smaller devices, which is why they have so few hours on them. Both originally sold for over $9,000 a few years ago. It's also the first large eBay purchase that my wife enthusiastically supported (after seeing the results). She loves seeing the big screen movies.Your mileage may vary,Kevin

Share this post


Link to post
Share on other sites

would you mind sharing a bit of detail about what to look for (and avoid) in buying a used front projector? I went through this exercise last year - not really very seriously but I was pondering it - but I couldn't figure out what I should be looking for brand-wise. Even $400 is too much if it doesn't work on arrival or is otherwise unsuitable.Thanks,Dave Blevins

Share this post


Link to post
Share on other sites

I think you'll find that the reason you don't see much of the pixels is because the projectors themselves very slightly blur the image, so that thepixels aren't as apparent as they might be. Whereas this doesn't affect the image much, it does look impressive. Might have something to do with using a very thin film or lens in front of the lcd itself before the image is enlarged.

Share this post


Link to post
Share on other sites

Hi Kevin,>>However, I don't see individual pixels as others have.:)Michael

Share this post


Link to post
Share on other sites

> would you mind sharing a bit of detail about what to look for> (and avoid) in buying a used front projector? Sure, here's a few tips from my two eBay purchases:1) I looked for used projectors that came from business auctions. Usually office machines are used very little compared to home projectors, since we all hate watching Powerpoint presentations . 2) Most bulbs last 2,000 hours and then need replacing at a cost of up to $400 or more. So look for low time projectors and/or one with a spare bulb. Also Google/eBay search for what a replacement bulb will cost so you know ahead of time. 2,000 doesn't sound like much, but I only use it a max of two hours a day, so that gives me ~3 years!3) If the seller says "I don't know how to check how much time is on this bulb", then find the original manufacturer's website and documents like I did, then write them with the (usually easy) instructions to bring up the bulb time on the display. My second projector I got cheap because no one else would bid, not knowing what the bulb time was, but his email reply to me showed it was super low.4) You really want 1024x768 and at least 700 lumens (for a darkened room) or 1000 lumens for a brighter room. (My flight room is kept in low light for flying.) I got an Infocus LP735, btw.5) Keystone correction is important, since you often can't mount the projector even with the screen. My projector automatically senses and adjusts for an offset angle of something like 15 degrees both horizontally and vertically, for example. Manual correction might be more handy, though.6) You might have need to make sure your choice can also be ceiling mounted (usually meaning it can invert the image since projectors are often mounted upside down). Or for rear projection, it must have a mirrored reverse projection mode.7) Make sure all the cables you need are included. Many have custom cables that are almost as expensive as the used projector!8) Make sure it doesn't have any color spots. Sometimes one of the filters will overheat in a spot and leave a dark/light spot. A bad pixel can also stand out, but for a low price it's liveable.That's all I can think of offhand. I'm sure others will jump in with other suggestions.Kev

Share this post


Link to post
Share on other sites

Thanks Kev for these notes. It is exactly what I was looking for.cheers,dB.

Share this post


Link to post
Share on other sites

The outside view has been discussed many times in this forum, and I certainly agree, it is one of the most crucial components of our hobby. It is probably the most simple component, if you have a bottomless pit of money, but most of us don't, so it becomes the most difficult.As I have explained to many of my friends, my hobby is no fun if I can't show it off. Most people that will see my sim won't understand the knobs, buttons, displays, controls, etc. But they will understand the outside view and the sense of motion (as Michael so well explains). So to me, I know I will have a major expense for the visuals.My vote is the projector, I'm currently or have been for about 6 months experimenting with the NEC LT240. I am totally sold on this unit. Check out the info here: http://www.nec-pj.com/products/g3_lt240.htm In my project work room, I have the projector setup. The Projector is 11' from the screen. The visual is almost 7' wide. I sit (or my eyes), are about 6' from the screen. If I concentrate I will see the pixels, otherwise I don't even notice them.Our 3D vision for the average person is only 10'. So my plan is to build a 180 degree spherical screen about 10' from the pilots point of view. I know that's going to take a lot of space.How many projectors will it take? The experiment will continues, like Michael said there are things in the works, I too saw the Gentleman from the Netherlands and his plans. How much will it cost? I bought this projector new for $3400.Until we are able to build a collimating mirror at an affordable price, we will struggle to perfect this part of our dream.Anyways.... that's my thoughts. I hope it helps.

Share this post


Link to post
Share on other sites

I too have struggled with this and so far, my vote goes to a projector. The sim is flown in a dark room (day or night) and this type of enviroment rally shows off the backlit panels, even when flying in daylight. The screen is mounted close to the ceiling in back of me and is "throwing" about 9 1/2 feet for a screen size in front of me of about 6 feet wide by 6 feet high. I have to use blinders in certain parts of the windscreen to block out the sideviews but the experieince is pretty immersive. The Projector id a Vioewsonic PJ501 andis only 800 Native and compressed to 1,072. The proof in the pudding is on approaches whereby everything gels pretty well for an excellent experince. I attempted the fresnel solution for a side view but I am not happy with the result..I too am awaitng the next wave of tehcnology before I invest in a second projector for my side view (Captain only). Here are some pics...

Share this post


Link to post
Share on other sites

Based on all information I collected, I decided on the fresnel lens solution.Last week I purchased a 19"x25" acrylic industrial quality lens from Edmund Optics. The cost was $202 plus UPS shiping to Israel, another $65. The lens arrived at my door in 48 hours (including custom clearance).The lens has 50 grooves per inch, 1250 grooves across, which results in about one groove per pixel.From first experiments (I didn't mount it yet, because it needs a plywood side cover - painted in black) I can say it was an excellent buy. You get a near real 3D feeling plus a large and cristal clear picture. No tint at all. I use two CRT monitors - 19" for view with the lens, operated by Active Camera. and 17" for instruments. The first monitor is connected to the motherboard and the second to the video card. This arrangement improve frame rate by about 30%.Active Camera gives you a free hand in deciding what part of the outside view you want to see relative to the dash board.Have funSeev

Share this post


Link to post
Share on other sites

Based on all information I collected, I decided on the fresnel lens solution.Last week I purchased a 19"x25" acrylic industrial quality lens from Edmund Optics. The cost was $202 plus UPS shiping to Israel, another $65. The lens arrived at my door in 48 hours (including custom clearance).The lens has 50 grooves per inch, 1250 grooves across, which results in about one groove per pixel.From first experiments (I didn't mount it yet, because it needs a plywood side cover - painted in black) I can say it was an excellent buy. You get a near real 3D feeling plus a large and cristal clear picture. No tint at all. I use two CRT monitors - 19" for view with the lens, operated by Active Camera. and 17" for instruments. The first monitor is connected to the motherboard and the second to the video card. This arrangement improve frame rate by about 30%.Active Camera gives you a free hand in deciding what part of the outside view you want to see relative to the dash board.Have funSeev

Share this post


Link to post
Share on other sites