Back on subject ...
lol... Assayer, you asked about brightness/dimness. In my opinion the image gets very subtly dimmer. Even though you are using more total pixels, there is enough reflection going on with the glass sides to where it does take away some of the light from your image. For example, if you don't make a cover over your two prisms of some sort there will be a resulting green image on your ceiling. (I just cover mine with a piece of paper for now).
I believe if you locate 'museum quality' glass or some other anti-reflective glass for the sides of your prisms you will minimize this effect. Although, I made my current design with regular picture frame glass and it hasn't bothered me enough to really hunt for anythign better on my next model (w/ fenceposts). By the way you can probably get whatever color combination you want for your fenceposts if you call up a fencing specialist. Home Depot will be limited in what it can get, whereas if you call a fencing specialist store, they will usually be able to get whatever you want in colors and sizes (although I don't think they make anything bigger than 5 x 5"... I asked them.)
Anyway.. as far as the dimming goes.. I couldn't really tell until I put SUPERMAN in and the beginning scenes with the glowing clothes stood out as being very slightly dimmer. I turned my lamp mode up to high power just to see if I could compensate and it did fine, but, I don't think it's noticable enough to bother for the most part.
lol... Assayer, you asked about brightness/dimness. In my opinion the image gets very subtly dimmer. Even though you are using more total pixels, there is enough reflection going on with the glass sides to where it does take away some of the light from your image. For example, if you don't make a cover over your two prisms of some sort there will be a resulting green image on your ceiling. (I just cover mine with a piece of paper for now).
I believe if you locate 'museum quality' glass or some other anti-reflective glass for the sides of your prisms you will minimize this effect. Although, I made my current design with regular picture frame glass and it hasn't bothered me enough to really hunt for anythign better on my next model (w/ fenceposts). By the way you can probably get whatever color combination you want for your fenceposts if you call up a fencing specialist. Home Depot will be limited in what it can get, whereas if you call a fencing specialist store, they will usually be able to get whatever you want in colors and sizes (although I don't think they make anything bigger than 5 x 5"... I asked them.)
Anyway.. as far as the dimming goes.. I couldn't really tell until I put SUPERMAN in and the beginning scenes with the glowing clothes stood out as being very slightly dimmer. I turned my lamp mode up to high power just to see if I could compensate and it did fine, but, I don't think it's noticable enough to bother for the most part.
I am going to review what others have done w/ the fencepost idea, but can anyone real quick confirm if they were able to sucessfully build this w/ two 4x4 inch pieces, or if you HAD to have the front lens be 5x5 ? I'm going to start small and work my way up to a large enough front lens be able to do 2.35
Thanks!
Thanks!
So whats up here boys. No action for a while I see.
I am getting ready to try this for the first time. So from what I understand the latest developements have been make 2 prisms with anti reflective glass on the optical pass, best black non reflective frame for the sides, and both filled with glycerin.
I have the angles from both the standard from Tor as well as from Slize.
Actually I want to confirm you angles please Slize. What are the cutting angles and the positioning angles relative to each other?
So what about the 2:35 movies? What are the angles and what kind of throw to image size should I shoot for to get acceptable barrel distortion.
I am getting ready to try this for the first time. So from what I understand the latest developements have been make 2 prisms with anti reflective glass on the optical pass, best black non reflective frame for the sides, and both filled with glycerin.
I have the angles from both the standard from Tor as well as from Slize.
Actually I want to confirm you angles please Slize. What are the cutting angles and the positioning angles relative to each other?
So what about the 2:35 movies? What are the angles and what kind of throw to image size should I shoot for to get acceptable barrel distortion.
When you say anything, you mean anything that minimized reflectiveness right? Black matte something right??
Yes, for best performance you want a dark matte finish on the interior side walls to minimize reflections. Realistically, most trying this project will build a prototype to work out the bugs in their process, and it probably is not so critical what the sides are made of for the prototype unit.
Your success with Glycerine will partially be a function of the glycerine used. I think mine must have had some impurities, possibly from the plastic bottles it was distributed in. When looking at it you could see a faint visible stratification. If possible, try to get all in one bottle.
Your success with Glycerine will partially be a function of the glycerine used. I think mine must have had some impurities, possibly from the plastic bottles it was distributed in. When looking at it you could see a faint visible stratification. If possible, try to get all in one bottle.
I have been playing around with my prototype each time we watch a movie on the setup, which is about once per week, playing around with the existing prisms to estimate how big of a front lense I'm gonna need to build for 2.35. It's going to need to be bigger than 5" tall to squeeze 2.35, I'm estimating more like 8", and I'm going to have to have it custom built at a plastic/acryllic shop.
I promise to post my results in the coming months once I actually get down there and put it to the test.
I promise to post my results in the coming months once I actually get down there and put it to the test.
ON the german board I saw the instructions were to build both prisms out of glass. This seems to make the most sense since glass will hold liquid just fine. But will I be alright with reflectiveness once I paint the sides(non optical parts) black matte?
These side panels can bassically be acrilic, glass or aluminium.
Thats pretty much it right? Aluminium seems the hardest because you have to get straight angles.
Are you guys using any precision protractor to measure the angles so critically or just a decent protractor?
No progress on the 2.35 prism? Hmmm. I may have to be the first one then.....
JudeBarnes, how are you playing around with these prisms for the 2.35? Do you try it with a 2:35 movie or a 1:85 movie?
What are you doing exactly? You have the 2 prisms mobile? Do you just tilt the larger prism more or both simultaneusly or what?
Give me some starting reference point.
Btw, at first try Glycerin does not seem to be the name they use here in Argentina. My next attempt is to describe to them what its used for? Anyone know?
These side panels can bassically be acrilic, glass or aluminium.
Thats pretty much it right? Aluminium seems the hardest because you have to get straight angles.
Are you guys using any precision protractor to measure the angles so critically or just a decent protractor?
No progress on the 2.35 prism? Hmmm. I may have to be the first one then.....
JudeBarnes, how are you playing around with these prisms for the 2.35? Do you try it with a 2:35 movie or a 1:85 movie?
What are you doing exactly? You have the 2 prisms mobile? Do you just tilt the larger prism more or both simultaneusly or what?
Give me some starting reference point.
Btw, at first try Glycerin does not seem to be the name they use here in Argentina. My next attempt is to describe to them what its used for? Anyone know?
Dracul, if you haven't already, you should read this entire thread, most of the info you're looking for is in there.
The most common oil people are using is "Mineral Oil" which you can pickup at any pharmacy here in the USA. I've never read any results of someone who compared mineral oil negatively compared to true glycerine.
The sides of your prism really don't matter that much so use whatever is the easiest to work with for YOU. For some people that's alluminum, others is acryllic, and others like to just go ahead & cut it w/ the glass cutters. The nice thing about making it out of glass is that you get a nice clean straight cut without having large powertools that you need to do it with acryllic or aluminum.
As far as what I'm doing with my prisms, mine ARE still indeed "loose", they are not mounted, and never have been! In fact, every single movie, my wife and I just setup the prisms on the fly and I've never gotten around to mounting them. Last time I watched a movie, I needed to get the front one tilted and my normal prop that I use wasn't around, so believe it or not I grabbed a star wars figure to prop it up on!!!
Anyway, as a result, yes, I can just move them both with my hands and try to find the right angles and dimensions to start contemplating the 2.35 design.
The most common oil people are using is "Mineral Oil" which you can pickup at any pharmacy here in the USA. I've never read any results of someone who compared mineral oil negatively compared to true glycerine.
The sides of your prism really don't matter that much so use whatever is the easiest to work with for YOU. For some people that's alluminum, others is acryllic, and others like to just go ahead & cut it w/ the glass cutters. The nice thing about making it out of glass is that you get a nice clean straight cut without having large powertools that you need to do it with acryllic or aluminum.
As far as what I'm doing with my prisms, mine ARE still indeed "loose", they are not mounted, and never have been! In fact, every single movie, my wife and I just setup the prisms on the fly and I've never gotten around to mounting them. Last time I watched a movie, I needed to get the front one tilted and my normal prop that I use wasn't around, so believe it or not I grabbed a star wars figure to prop it up on!!!
Anyway, as a result, yes, I can just move them both with my hands and try to find the right angles and dimensions to start contemplating the 2.35 design.
Slize mentioned that Glycerin does not attack the glue so there is less chance of a leak with glycerin over mineral oil is there not?
Also, how do I calculate my screen size when I plan to use an anamorphic for 1:85 movies and maybe 2:35?
I would prefer to use a scaler through my HTPC for constant height with say Theatertek and something else for 4:3 satellite. Then when I want to watch 1:85 dvd I slap on the anamorphic. Will the screen width get wider now while height remains the same. And now lets say I have another 2:35 anamorphic lens and movie I want to watch so I slap that lens on and even wider yet while height remains the same?
The maximum screen I can have is 9 feet wide(not diagnol).
I would prefer to use a scaler through my HTPC for constant height with say Theatertek and something else for 4:3 satellite. Then when I want to watch 1:85 dvd I slap on the anamorphic. Will the screen width get wider now while height remains the same. And now lets say I have another 2:35 anamorphic lens and movie I want to watch so I slap that lens on and even wider yet while height remains the same?
The maximum screen I can have is 9 feet wide(not diagnol).
Went to a glass shop and they showed me picture frame glass.
When I held this up looking through it looks frosted. Everything is softened big time. When I place it right up against a photo the image is clear and sharp. The guy assured me this is photo frame anti reflex glass. Does this sound right to you guys. Is this what I need.
When I held this up looking through it looks frosted. Everything is softened big time. When I place it right up against a photo the image is clear and sharp. The guy assured me this is photo frame anti reflex glass. Does this sound right to you guys. Is this what I need.
see if you can get a few scrap pieces of that glass from your contact, bring them home, and put them in front of your projector (with no liquids yet in them in prism form, of course). Just hold them up so the image passes through them, and see what you get. If you see the image affected negatively at all scrap that glass and look for other types. Maybe others will chime in who have more experience. The prototype we've used for the past year is just cheap frame glass and works fine. It probably is anti reflective glass but there are many types of anti reflective glass. This one in particular might just be for printed matter that is hung in offices, that will keep the sun from damaging the documents inside. I've also talked to glass experts and even online you can find AR glass at fairly steep prices. Each may have different applications, though. It's also referred to as "museum glass".
On your question about heights / screen size / etc. Remember that the lense when used in it's traaditional manner keeps a constant width. It simply affects your vertical dimensions, not your horizontal ones. So, you won't have to move your projector at all. Just put the lense (which are two filled prisms) in front when you want to use it, change your aspect ratio settings on your HTPC, and it will squeeze to 1.85 or 2.35 depending on how steep you set the front prism's angle.
Once I build a 2.35 version of these prisms I plan to make a 126.9 inch x 54 inch screen (currently I'm using a 96 x 54). Most of the films we watch will be 2.35 so it will fit perfectly in the screen dimensions. When we watch 1.85 I'll just move the projector a little closer to the screen, tilt the same prism to 1.85 and just use 96 x 54 inches worth of the screen. If I watch 4:3 projector in same position as for 1.85 and aspect ratio set to anamorphic so that there would be grey bars on the left and right.
I might mask with velcro and black felt the unused white portions of the screen to either side of the 1.85 or 4:3.
On your question about heights / screen size / etc. Remember that the lense when used in it's traaditional manner keeps a constant width. It simply affects your vertical dimensions, not your horizontal ones. So, you won't have to move your projector at all. Just put the lense (which are two filled prisms) in front when you want to use it, change your aspect ratio settings on your HTPC, and it will squeeze to 1.85 or 2.35 depending on how steep you set the front prism's angle.
Once I build a 2.35 version of these prisms I plan to make a 126.9 inch x 54 inch screen (currently I'm using a 96 x 54). Most of the films we watch will be 2.35 so it will fit perfectly in the screen dimensions. When we watch 1.85 I'll just move the projector a little closer to the screen, tilt the same prism to 1.85 and just use 96 x 54 inches worth of the screen. If I watch 4:3 projector in same position as for 1.85 and aspect ratio set to anamorphic so that there would be grey bars on the left and right.
I might mask with velcro and black felt the unused white portions of the screen to either side of the 1.85 or 4:3.
I should add that if I watch 4:3 I might mask off the small grey bars, also, BUT... I've found that watching lots of 4:3 especially cartoons, I don't bother to change my aspect ratio, and in effect I convert 4:3 to 1.85 and it still looks pretty good. Not awkward enought o bother changing it. (The figures being a little shorter and squattish than originally intended).
When you have actual film material with real people/actors and such, then their proportions look a bit awkward so it's worth changing the aspect ratio when using the lense & 4:3.
When you have actual film material with real people/actors and such, then their proportions look a bit awkward so it's worth changing the aspect ratio when using the lense & 4:3.
I also forgot to add that to date (going on over a year now) the mineral oil I used has not done anything negative to the E-6000 bonding material/glue I used to join my prism sides together.
So I need to make a variable focus projector than. You have a diy projector or a commercial projector?
So If I keep my projector at the same distance the 2.35 prism and movie will be the largest right? So the width stays the same only the height changes?
You mean if my 4:3 (no prism) size is 100w x75h inches
the 1:85 image will be 100W x 54H inches and 100W x 42H inches for 2:35 ? So the width stays the same just the height gets smaller on the screen the wider aspect ratio is used?
This glass I saw looks great over the large picture frame. When the guy showed it to me I couldnt believe that there is actually glass there. Seems to do a great job on antireflex.
So If I keep my projector at the same distance the 2.35 prism and movie will be the largest right? So the width stays the same only the height changes?
You mean if my 4:3 (no prism) size is 100w x75h inches
the 1:85 image will be 100W x 54H inches and 100W x 42H inches for 2:35 ? So the width stays the same just the height gets smaller on the screen the wider aspect ratio is used?
This glass I saw looks great over the large picture frame. When the guy showed it to me I couldnt believe that there is actually glass there. Seems to do a great job on antireflex.
you're correct on the dimensions if you leave your projector in place, the height changes but the width stays exactly the same. Up until now I've been using a 96 x 54 screen and watching 1.85 on it using the full screen, 2.35 films have grey bars at the top and bottom but I'm still squeezing it the same w/ the same lense. 4:3 has grey bars on the left and right but I still have to use the lense because I can't move the projector any closer than it already is and 4:3 would spill over the height of my screen without the lense to condense it.
Keep us updated on that glass. See if they'll sell you a small scrap piece only about 3" x 3" or so to shine your projector through it.
Oh by the way, in my particular case my projector is a Panasonic PT-LC75U, which was a fairly popular XGA projector 1.5 years ago.
Oh by the way, in my particular case my projector is a Panasonic PT-LC75U, which was a fairly popular XGA projector 1.5 years ago.
Test Software
About 1 week ago I was watching football with my multimedia projector in 4x3 mode. I thought, that all this light and resolution would benefit my movies (also my brothers TV has a special mode for widescreen DVDs with compressed vertical). I knew anamorphic lenses existed for movies and decided that some geeks must have developed them for home projectors. (I too am a movie and physics geek). I am so glad I was able to find this forum and Hustvedt's site. I will make a lense sometime soon but first I need some help. Please tell me what oils, glycerin, turpentine, etc is the clearest, and please lets attempt to compile all of our glass info. Reflection should be a huge problem for this type of set-up from what I understand about optics. For your trouble, I share by plan tester. This excel program models, indexes of refraction, prism angle, and angle of the prisms. This should help people figure out how to make 2.35 lenses. I don't have a zipper installed so just change .zip to .xls.
Panisonic RP82
Canon LV-S2 (the X2 is cheaper than mine in 1 year)
Sherwood 6.1 with 11 BostonA and CambridgeSW speakers
About 1 week ago I was watching football with my multimedia projector in 4x3 mode. I thought, that all this light and resolution would benefit my movies (also my brothers TV has a special mode for widescreen DVDs with compressed vertical). I knew anamorphic lenses existed for movies and decided that some geeks must have developed them for home projectors. (I too am a movie and physics geek). I am so glad I was able to find this forum and Hustvedt's site. I will make a lense sometime soon but first I need some help. Please tell me what oils, glycerin, turpentine, etc is the clearest, and please lets attempt to compile all of our glass info. Reflection should be a huge problem for this type of set-up from what I understand about optics. For your trouble, I share by plan tester. This excel program models, indexes of refraction, prism angle, and angle of the prisms. This should help people figure out how to make 2.35 lenses. I don't have a zipper installed so just change .zip to .xls.
Panisonic RP82
Canon LV-S2 (the X2 is cheaper than mine in 1 year)
Sherwood 6.1 with 11 BostonA and CambridgeSW speakers