morkys said:
Or use min zoom (smallest image) but pull the projector back further, which often limits users wanting to go with a VC lens...
In the case of simply zooming, my projector is 1:1 to 1.3:1...
Mark
Right. I cannot move my projector any farther back than 13 feet so that is my most constricting limitation. If you have a lot of room to move backward and you can zoom down you can take better advantage of different lens.
So morkys, are you wanting a VC to reduce the image size given that your so close? Just becareful with too much zoom...
Mark
Mark
I am awaiting the Vikuiti films to arrive--I am cautiously optimistic they may help. Got a quote back from an optical coatings company--$1000 and up, depending on the precise coating requested.
Anyway, the vikuiti films should arrive in a couple of days. But these costs for the coatings must be where the price of the prismasonic prisms come from. Of course, in a perfect world, you wouldn't want any reflections. But in reality, the reflections can be minimized, and only appear in certain scenes (seems to occur most frequently in the credits. Honestly, with the apparent benefit of the anamorphic prism in a sub $100 DIY system, would you pay $1000 for what seems like an incremental benefit?
Anyway, the vikuiti films should arrive in a couple of days. But these costs for the coatings must be where the price of the prismasonic prisms come from. Of course, in a perfect world, you wouldn't want any reflections. But in reality, the reflections can be minimized, and only appear in certain scenes (seems to occur most frequently in the credits. Honestly, with the apparent benefit of the anamorphic prism in a sub $100 DIY system, would you pay $1000 for what seems like an incremental benefit?
prism
I ordered one J25 and another J24 prisms. guys do you think I should have ordered two J25 prisms.
I am going to install new pani PJ 100AX.
Also to get 120 diagonal screen size what whould be the screen lenth I need with this these prism.
Thank you
I ordered one J25 and another J24 prisms. guys do you think I should have ordered two J25 prisms.
I am going to install new pani PJ 100AX.
Also to get 120 diagonal screen size what whould be the screen lenth I need with this these prism.
Thank you
Well, despite some good advice to just buy the prism wedges, I went ahead and made a couple of acrylic water prisms this weekend to play around with. I got a 1/4 inch acrylic sheet from Lowe's, cut it up into pieces to make two prisms that were 8 inches on the hypotenuse with an angle of 23 degrees. Cutting the acrylic was trickier than I originally thought...I made one cut with a miter saw too quickly, and had what can only be described as a blow-out. Small pieces of acrylic exploded from the edge and flew back at my face. Glad I had safety glasses on. But after that I had no problems as long as I made the cuts slowly.
After all the pieces were cut, I glued it all together using some Weld-On #16 solvent/cement. It was pretty messy and I accidently got some of the cement on one of the faces, but altogether I was pretty happy with the way it turned out since this was my first attempt at making prisms. One of the prisms had no leaks at all, and the second one had a small leak that I was able to fix with another bead of Weld-On. I filled both prisms with water through a 3/8 inch hole drilled in the top of both prisms and VOILA... my first anamorphic lens was born.
Alignment took a little while, but wasn't as bad as I had feared. There is some distinct pincushioning that I think is inherent in this design. I balanced out the top and bottom curvature a bit by tilting both prisms, but couldn't get rid of the pincushioning so I'm thinking that I am stuck with it, at least with these prisms. Does anyone know if the glass prisms exhibit less pincushioning than water prisms? I'm also wondering if prisms of a different angle (either larger or smaller) would have different pincushion characteristics.
I saw some big reflections on the right and left side of the screen, but was able to fix this by putting some blue plastic tape on the small prism sides. Black tape is probably better, but all I had on had was blue stuff, and it seemed to do the job.
I did notice quite a bit of CA on the edges, but it wasn't noticable while watching a movie (The Mummy Returns). Also saw that I had a little bit of astigmatism because a test pattern of vertical lines wouldn't focus at quite the same spot as horizontal lines. I'm not sure if it was due to a problem with my prism, alignment, or something else. Any suggestions are welcome.
Even with all the little problems, I was amazed at the wonderful large screen with no black bars. The clarity was much better than I had expected with water prisms. It was perfectly watchable, and will hopefully only get better if I move to glass.
Thanks for all the good discussion on CIH prisms... I wouldn't have even thought to try this without all the work you guys have done up to this point.
Ed
After all the pieces were cut, I glued it all together using some Weld-On #16 solvent/cement. It was pretty messy and I accidently got some of the cement on one of the faces, but altogether I was pretty happy with the way it turned out since this was my first attempt at making prisms. One of the prisms had no leaks at all, and the second one had a small leak that I was able to fix with another bead of Weld-On. I filled both prisms with water through a 3/8 inch hole drilled in the top of both prisms and VOILA... my first anamorphic lens was born.
Alignment took a little while, but wasn't as bad as I had feared. There is some distinct pincushioning that I think is inherent in this design. I balanced out the top and bottom curvature a bit by tilting both prisms, but couldn't get rid of the pincushioning so I'm thinking that I am stuck with it, at least with these prisms. Does anyone know if the glass prisms exhibit less pincushioning than water prisms? I'm also wondering if prisms of a different angle (either larger or smaller) would have different pincushion characteristics.
I saw some big reflections on the right and left side of the screen, but was able to fix this by putting some blue plastic tape on the small prism sides. Black tape is probably better, but all I had on had was blue stuff, and it seemed to do the job.
I did notice quite a bit of CA on the edges, but it wasn't noticable while watching a movie (The Mummy Returns). Also saw that I had a little bit of astigmatism because a test pattern of vertical lines wouldn't focus at quite the same spot as horizontal lines. I'm not sure if it was due to a problem with my prism, alignment, or something else. Any suggestions are welcome.
Even with all the little problems, I was amazed at the wonderful large screen with no black bars. The clarity was much better than I had expected with water prisms. It was perfectly watchable, and will hopefully only get better if I move to glass.
Thanks for all the good discussion on CIH prisms... I wouldn't have even thought to try this without all the work you guys have done up to this point.
Ed
Holy crap... I just got a quote from L&L Optical Services in California for $40 each prisms for MgF2 (Magnesium Fluoride) or $80 each prism for Broadband optical coating... Delivery one to two weeks after receipt of the prisms...
The contact over there is Richard LaRue at richard@llopt.com
Their website is http://www.llopt.com
I think I will wait until I get the vikuiti films, but I thought I would pass this along to others in case there is interest.
The contact over there is Richard LaRue at richard@llopt.com
Their website is http://www.llopt.com
I think I will wait until I get the vikuiti films, but I thought I would pass this along to others in case there is interest.
Sorry--too late to edit my previous post. Here is the webpage on their AR coatings. http://www.llopt.com/ar.html#bb
My anamorphic lens setup
Thanks to all the information posted here, I was able to construct an anamorphic lens that works great! I thought I will post a write-up. The only thing new in here is a drawer slide setup that alows me to move the lens in and out of the light path.
Due to the larger size of the PDF file, I am hosting it at:
www.caltos.com/Anamorphic.pdf. It is a slow website, so might take a few minutes to download.
Thanks to everyone for the great info in this thread!
Thanks to all the information posted here, I was able to construct an anamorphic lens that works great! I thought I will post a write-up. The only thing new in here is a drawer slide setup that alows me to move the lens in and out of the light path.
Due to the larger size of the PDF file, I am hosting it at:
www.caltos.com/Anamorphic.pdf. It is a slow website, so might take a few minutes to download.
Thanks to everyone for the great info in this thread!
Re: My anamorphic lens setup
Fantastic work. I like the idea of the slots on the housing--it allows the prisms to be highly adjustable, if needed.
By the way, I removed the final period from your link that I quoted--it should work now.
dvarma said:
Fantastic work. I like the idea of the slots on the housing--it allows the prisms to be highly adjustable, if needed.
By the way, I removed the final period from your link that I quoted--it should work now.
Sorry, in my previous post, there is an extra period at the end of the link. It should be:
www.caltos.com/Anamorphic.pdf
www.caltos.com/Anamorphic.pdf
dvarma: Nice job! Thanks very much for posting the pdf file with all of the pictures. I've been trying to think of how to mount my lens so that it can be retracted and was thinking about drawer slides, but I kept thinking that I'd make it like a drawer with two slides. I never thought to use just one like you did. You saved me a lot of work on that one.
And I like your bracket for adjusting the height and angle of the lens. All in all, a nice adjustable system.
And I like your bracket for adjusting the height and angle of the lens. All in all, a nice adjustable system.
Mark Techer said:
Nope. I am not interested in a VC lens at all anymore. I was only looking for one earlier because I wasn't aware of the difference between VC and HE lens. I thought a cheap used Panamorph 752's would work but as a VC lens it will not work. I realize now that my throw ratio pretty much eliminates my using a VC lens. If I did buy a lens, I would use an HE lens. I prefer the HE setup anyhow, since it makes more sense. You setup your projector to shoot your ideal 16:9 screen size with your constant height, and then you only need to stretch the image electronically and then stretch it horizontally with the lens and you are done, and to go back to 16:9 you just reverse the process. No need to touch the zoom. If I can coat my prisms with a proper anti-reflective coating such as Steve may have found, then I will do that and probably coat all 4 prisms.
Dvarma,
I saw a post you did at AVS but didn't reply as I didn't want to look like I was pushing the DIY lens there too hard - there is an Aussie with the tag Darma who recently bought an Aussiemorphic Lens off me. This thread statred back in 2002 was for that exact reason 🙂
Great work and very inventive with the slots and bolts...
Mark
I saw a post you did at AVS but didn't reply as I didn't want to look like I was pushing the DIY lens there too hard - there is an Aussie with the tag Darma who recently bought an Aussiemorphic Lens off me. This thread statred back in 2002 was for that exact reason 🙂
Great work and very inventive with the slots and bolts...
Mark
I got the Vikuiti films in yesterday. Unfortunately, we had our holiday party for work last night, and I didn't get home until late--I was exhausted, so I had to table my review until this evening.
Thanks, Mark. If you remember it was your PM to my question on AVS forum a few months ago about prism sources that sent me over here to discover this treasure of a thread 😉
It's no coincidence that the case looks almost exactly like (except I haven't yet cut out the corners on top and bottom on the short side of the case) the Aussiemorphic lens.
Also, I can't tell for sure, but taping two AR coated glasses (one each on each prism) on to the prisms on the projector sides seem to have helped a bit. I know it is not like a real AR coating, as there is potentially gap at the interface, and maybe it is a psychological effect, but I do think it helped. I used the source someone posted on this thread a few weeks back. I am waiting for someone to try and see if they can get the prisms AR coated cheaply. I can't take mine out as they are already epoxied to the bolts, but if it does work I might get a new pair.
Thanks to Mark, Mike, Steve and numerous others for the great info on this wonderful thread!
It's no coincidence that the case looks almost exactly like (except I haven't yet cut out the corners on top and bottom on the short side of the case) the Aussiemorphic lens.
Also, I can't tell for sure, but taping two AR coated glasses (one each on each prism) on to the prisms on the projector sides seem to have helped a bit. I know it is not like a real AR coating, as there is potentially gap at the interface, and maybe it is a psychological effect, but I do think it helped. I used the source someone posted on this thread a few weeks back. I am waiting for someone to try and see if they can get the prisms AR coated cheaply. I can't take mine out as they are already epoxied to the bolts, but if it does work I might get a new pair.
Thanks to Mark, Mike, Steve and numerous others for the great info on this wonderful thread!
crosshatch for my setup
Here is a cross hatch that shows geometric distortion and CA I am getting with my setup. Not bad.
BTW, the screen I am using is made from the Wilsonart Designer White laminates, and is 110 inches wide (2.35 AR of course!). The Z4 is just about enough in a dark room.
Here is a cross hatch that shows geometric distortion and CA I am getting with my setup. Not bad.
BTW, the screen I am using is made from the Wilsonart Designer White laminates, and is 110 inches wide (2.35 AR of course!). The Z4 is just about enough in a dark room.
Attachments
dvarma, I don't know if it is too late to do this with your enclosure or not, but it looks like the prism closest to the screen needs to be adjusted to the right (as you are looking at the screen). I think that might be the cause of your severe color problem on the right edge of the screen.
Remember that the light beam coming from the first prism is like a rainbow. The first prism splits the beam into colors. This spreads the beam horizontally and makes it wider. (see How Rainbows work)
When this rainbow beam hits the second prism, the colors are re-integrated (because the second prism has the same geometry as the first).
The red colors are bent the least, and the blue colors are bent the most. Using Mark's prism geometry, and looking into the first prism from the projector towards the screen, the beam enters the first prism, and is bent towards the right, with the blue colors bent the most.
If your second prism is too far to the left, then the blue colors are not hitting the second prism on the right-most edge of your picture, resulting is a loss of blue (makes the image redder).
When aligning the prisms, it's important to put a piece of paper against the inner-face of the second prism to see the incoming beam to make sure you are catching all of it.
For this reason, I have the hypotenuse of the second prism facing inward because this is the surface that really needs to be the largest to catch as much refracted blue light as possible.
More physics in action! 😎
Remember that the light beam coming from the first prism is like a rainbow. The first prism splits the beam into colors. This spreads the beam horizontally and makes it wider. (see How Rainbows work)
When this rainbow beam hits the second prism, the colors are re-integrated (because the second prism has the same geometry as the first).
The red colors are bent the least, and the blue colors are bent the most. Using Mark's prism geometry, and looking into the first prism from the projector towards the screen, the beam enters the first prism, and is bent towards the right, with the blue colors bent the most.
If your second prism is too far to the left, then the blue colors are not hitting the second prism on the right-most edge of your picture, resulting is a loss of blue (makes the image redder).
When aligning the prisms, it's important to put a piece of paper against the inner-face of the second prism to see the incoming beam to make sure you are catching all of it.
For this reason, I have the hypotenuse of the second prism facing inward because this is the surface that really needs to be the largest to catch as much refracted blue light as possible.
More physics in action! 😎
dvarma said:
Glad to help--this has been really fun for me to figure out. As for your comment above--I am hoping that the apparent reduction in glare and reflections with using AR coated glass is not just psychological, since I am attempting something similar by using the vikuiti films.