The grand plan is the AT screen for sure, but morkys gave me his old screen material to play with, to check out sizing and such and I'm a cheap guy, so I can certainly make due with that for a while... and yes, I can wait till Christmas for the projector, have to work with the budget you know. I think the hardest part will be waiting until I can get the full sound going, it is going to suck to have the big screen and crappy sound 🙂
Hey Roar, sorry I did not get anything 🙁
maybe my newbie privilages...
my email skiagain@gmail.com
Thanks!
maybe my newbie privilages...
my email skiagain@gmail.com
Thanks!
I could of clicked the wrong 'email' button... if so someone else got your email 🙂 Or it could be in your 'spam' box because it was sent from a hotmail address, regardless I just sent you the coles notes version.
First let me say "Thank you!" to Mark and all the people here that have put in so much work on this project. I was another person that was following the liwuzen lens on the AVS forums. I just couldn't justifiy buying a Prismasonic or Panamorph but I really wanted a CIH setup. Now I have one!
A friend and I bought the "lenses" from Massillon and they arrived on Wednesday. After playing all weekend I now can say that this prism setup is nothing short of fantastic. I'm still not finished with the Prism box because I got caught up with watching Batman Begins and "testing" other movies. My set up is below...
Optoma HD72
Toshiba HD-A1 player
54"x130" BOC screen
2 5x7 (J25) prisms
I used black tape around the lenses and then glued on a thin (size of bolt head) piece of wood that matched the upper and lower surfaces of the prism. Before glueing I cut a bolt head sized/shaped hole in the wood. This allowed the entire wood/bolt mechanism to turn the prism, so I wouldn't have to rely on the just the bolt holding onto the prism. The use of tape underneath also allows me to scrap the whole thing later without damaging the lenses in any way.
I have a couple of questions on finishing the kit. What type of knobs are you all using to turn the lenses. I bought a couple of cheap ones from Home Depot that fit over a nut. I'm thinking of using a nut/lock washer/nut/knob combo that will hopefully keep the last nut in place and turn the lenses instead of unscrewing the nut. Also what type of locking feature are you using for the knobs. From playing around this weekend, I'm not as worried about this since you cannot see the difference if the stretch is off by an inch or so but it would be nice to have the knob lock into place.
Thanks again all for all the hard work. I'll say a quick blessing to the home theater gods for you before every movie.
Marc
A friend and I bought the "lenses" from Massillon and they arrived on Wednesday. After playing all weekend I now can say that this prism setup is nothing short of fantastic. I'm still not finished with the Prism box because I got caught up with watching Batman Begins and "testing" other movies. My set up is below...
Optoma HD72
Toshiba HD-A1 player
54"x130" BOC screen
2 5x7 (J25) prisms
I used black tape around the lenses and then glued on a thin (size of bolt head) piece of wood that matched the upper and lower surfaces of the prism. Before glueing I cut a bolt head sized/shaped hole in the wood. This allowed the entire wood/bolt mechanism to turn the prism, so I wouldn't have to rely on the just the bolt holding onto the prism. The use of tape underneath also allows me to scrap the whole thing later without damaging the lenses in any way.
I have a couple of questions on finishing the kit. What type of knobs are you all using to turn the lenses. I bought a couple of cheap ones from Home Depot that fit over a nut. I'm thinking of using a nut/lock washer/nut/knob combo that will hopefully keep the last nut in place and turn the lenses instead of unscrewing the nut. Also what type of locking feature are you using for the knobs. From playing around this weekend, I'm not as worried about this since you cannot see the difference if the stretch is off by an inch or so but it would be nice to have the knob lock into place.
Thanks again all for all the hard work. I'll say a quick blessing to the home theater gods for you before every movie.
Marc
roar,
Just a warning. Although I understand your situation by way of your room setup, I think you should consider all options in terms of screen and speaker placement. Have you priced acoustically transparent screen material? It is quite pricey and the sound is never quite as good as without. Just a thought.
Just a warning. Although I understand your situation by way of your room setup, I think you should consider all options in terms of screen and speaker placement. Have you priced acoustically transparent screen material? It is quite pricey and the sound is never quite as good as without. Just a thought.
artbypaul said:
Yeah Paul that is a good idea as these prisms are not antireflection coated, so yet can produce reflections on the side and rear walls - someone called it surround vision...
mbonikow said:
Are those sizes metric? If so, it looks like the largest they make is 50mm or 2". The link also shows that they make equalateral prisms (60degrees). These could work as a rear optic of a VC lens...
Give them a go, and I hope that you have better luck than I did when sourcing large, custom made BK7 prisms. The quote for 4 prisms came back at $10.5K...
Mark
Hi Mark!
Forget the link above, this was just an example. I send you an email with some details. Cheers!
Forget the link above, this was just an example. I send you an email with some details. Cheers!
morkys said:
The AT material I'm looking at is the SMX material, though not cheap it seems to be one of the best options and compared to the big companies, at te cost of $285 for 3 yards it seems like a good deal... there are all sorts of test results on the smx website in regards to the AT properties of the screen and it seems pretty good, I figure if it is good enough for Alan's HT over at avs it is good enough for my little piece of soon to be heaven 🙂
The only part that bothered me with the SMX product was that it is said to be "directional" meaning that it must be fixed a certain way to work. This meant that you have to purchase more material than would normally be required (say BOC for example) to make the same size screen.
I am not sure if this is a real reason or a method of selling more product.
Having worked with AT screens before (a HT Stewart Miroperf screen), they are allow the very best splice of sound and picture. Hearing the sound actually coming from the image is something that needs to be experienced to be believed. I was totally blown away with the results, but the price of the said screen is cost prohibitive for most, so SMX's DIY solution looks appealing if indeed it is as good as the claims...
Mark
I am not sure if this is a real reason or a method of selling more product.
Having worked with AT screens before (a HT Stewart Miroperf screen), they are allow the very best splice of sound and picture. Hearing the sound actually coming from the image is something that needs to be experienced to be believed. I was totally blown away with the results, but the price of the said screen is cost prohibitive for most, so SMX's DIY solution looks appealing if indeed it is as good as the claims...
Mark
morkys said:
The Panamorph 752 is a vertical Compression lens( Constant width) you seem to be after a HE lens.
I need a VC lens. Are you going to purchase the 752? If not could you point me in that direction
Thanks
Moderators; when do I get full rights, so I can email members etc
In terms of SmX - I followed that thread through development, and got in on the bargain basement first run. The directional aspect arose because a member, EBR, bought 2 yards and made a screen for use with a Ruby. It moired pretty severley. Initially people thought the weave wouldn't work with a 1080p projector. Then another member discovered that the moire varied based on directionality of the weave.
I guess you could argue its a feature, not a bug, given it results in higher sales, but the discover was made by people other than Rueben (who offered to help EBR fix his problem, but EBR decided to skip the AT screen).
I can't make an endorsement, since my screen is still in a box, and I don't own a PJ.
I guess you could argue its a feature, not a bug, given it results in higher sales, but the discover was made by people other than Rueben (who offered to help EBR fix his problem, but EBR decided to skip the AT screen).
I can't make an endorsement, since my screen is still in a box, and I don't own a PJ.
I'm still interested in his product, but right now I just don't have the room for an AT screen. It would be so cool though. Next to CIH, an AT screen has been on my wish list for several years.
In my previous set ups, the speaker baffles and screen have been in a vertical line, and right now, the speakers are in front of the screen's (under but forward) vertical plain, so I could not afford the space to bring the screen out as would be needed with an AT screen...
Mark
In my previous set ups, the speaker baffles and screen have been in a vertical line, and right now, the speakers are in front of the screen's (under but forward) vertical plain, so I could not afford the space to bring the screen out as would be needed with an AT screen...
Mark
Mark Techer said:
Mark are you asking me
😕
If so, I might build one but because of my short throw (1.6) and wanting it to be a VC lens, I would need the largest trophies. My image at 4" is 5 1/2" wide so I need the 6" wide prisms. the 6" by 7/12" prisms will require one heck of a big box.
I am now wondering if I could get the prisms cut at about 4" in length. So I would have 4x6 but in the other orientation. I am going to see if I can find out who makes them for Massilon plaque and see if they can be cut.
Correct me if I'm wrong about HE vs VC
He're my thoughts about the benefits of a VC set up as opposed to a HE setup.
I am assuming that the lenses work best when the PJ is farthest from the screen. The farhter away, the more square on I am projecting the image. If my Pj is closer I would be shooting at more of a downward angle from the ceiling. Am I correct that a smaller projecting angle is better than a steep one?
More square on projecting should result in less image bowing, curving, etc. and I assume less CA. BTW, what is CA? I don't know what the abbreviation stands for but I gather it is a image distortion of some type.
So If I move my PJ farther back I can place it so I have the screen to the width I want and then use the prisms to VC the image. If my thought process is correct, then I should have less image distortion by using the prisms in a VC orientation?
My PJ is a short throw Sharp DT200. I project a 75 inch diagonal (16:9) image from about 9 feet. I want to go slightly larger (up to roughly 85-90 inches diag) and that will further increase the projection angle.
Has anyone else gone the VC route with these prisms?
Thanks
He're my thoughts about the benefits of a VC set up as opposed to a HE setup.
I am assuming that the lenses work best when the PJ is farthest from the screen. The farhter away, the more square on I am projecting the image. If my Pj is closer I would be shooting at more of a downward angle from the ceiling. Am I correct that a smaller projecting angle is better than a steep one?
More square on projecting should result in less image bowing, curving, etc. and I assume less CA. BTW, what is CA? I don't know what the abbreviation stands for but I gather it is a image distortion of some type.
So If I move my PJ farther back I can place it so I have the screen to the width I want and then use the prisms to VC the image. If my thought process is correct, then I should have less image distortion by using the prisms in a VC orientation?
My PJ is a short throw Sharp DT200. I project a 75 inch diagonal (16:9) image from about 9 feet. I want to go slightly larger (up to roughly 85-90 inches diag) and that will further increase the projection angle.
Has anyone else gone the VC route with these prisms?
Thanks
CA is chromatic aberration--which is the distortion the image has due to the different wavelengths of light traveling through the glass of the prisms. It's what causes a prism to split a light beam into its component colors. This why you use a double prism. Theoretically, you can reduce CA by turning the front prism around, and making the split beam reconverge (to a degree). It's not perfect, however, and most prism-based systems have some degree of CA.
http://en.wikipedia.org/wiki/Chromatic_aberration
http://en.wikipedia.org/wiki/Chromatic_aberration
I have not gone for the lens quite yet. I will see if I cannot try the prisms tonight. I have my iScan HD+ hooked up and should be able to do the vertical stretch no problem. I just need to figure out how to put the prisms in front of my projector temporarily.
Re: Correct me if I'm wrong about HE vs VC
Good point, but if your considering buying a commercial product, size is the main concern. It has been said many times before that the manufactures of theses lenes need larger rear optics.
At this point in time, I would not be worried about a "Big Box". My first lenses were huge, at some 14" wide, where today I have refined the design down to a bit less than an 8" cube...
Correct, as the closer your projector is to the screen, the wider the angels that make the image will be. This is why my short throw is not ideal (though I made it work) for CIH...
Steve's post on CA is very informative. The opposing axies of the prisms seem to be the key to correct CA. Your theory on projecting a straight image is valid, as the anamorphic lens will only magnify any keystone errors etc...
Well that is Panamorph's theory as well... You still get some barrel, but pincushion seems to be reduced. The oddest thing about prisms based lenses is that the stretch/compression is not 100% uniform across the screen. You can see this with a horizontal pan of a stationary object with a HE lens.
However, reports from VC lens owners indicate that this problem also affects VC lenses, where the non uniform (now compression) image manipulation is now seen on vertical pans.
Some of these claims have been denied by their manufactures, but from what I understand about prisms based lenses, you can not correct for focus and non -uniform stretch or compression is a by- product of bending light using a prism pair...
If you want to go larger, I think you need to go HE, but yes I have tried the VC with my lens. It was interesting. It didn't work out 100% becuase my beam was too wide for the prisms (7.5 x 5.5") that were now standing up on the ends (5.5 x 7.5", so I did get image clip at the sides.
Over all however, it did prove that a HE could be used as a VC if the prisms are large enough.
The key reson I wanted to try this is that I actually need to reduce my screen size from the current 8 foot wide down to about 6 feet. Turning the lens meant that my image width was now the same as the native 16:9 beam, but the height was also now reduced by 33%. At my current seating distance, this worked out to be much better than the larger screen size.
The other thing I found was there was a noticable increase in image brightness from comrpessing the 100% light into a 66% sized screen area.
For me to do this, I will need to source even larger prisms. I have found the prisms I need, but not sure if the supplier can deliver as yet...These larger prisms are 220mm x 180mm...
Mark
D_B_0673 said:
Good point, but if your considering buying a commercial product, size is the main concern. It has been said many times before that the manufactures of theses lenes need larger rear optics.
At this point in time, I would not be worried about a "Big Box". My first lenses were huge, at some 14" wide, where today I have refined the design down to a bit less than an 8" cube...
johnstof said:
Correct, as the closer your projector is to the screen, the wider the angels that make the image will be. This is why my short throw is not ideal (though I made it work) for CIH...
Steve's post on CA is very informative. The opposing axies of the prisms seem to be the key to correct CA. Your theory on projecting a straight image is valid, as the anamorphic lens will only magnify any keystone errors etc...
Well that is Panamorph's theory as well... You still get some barrel, but pincushion seems to be reduced. The oddest thing about prisms based lenses is that the stretch/compression is not 100% uniform across the screen. You can see this with a horizontal pan of a stationary object with a HE lens.
However, reports from VC lens owners indicate that this problem also affects VC lenses, where the non uniform (now compression) image manipulation is now seen on vertical pans.
Some of these claims have been denied by their manufactures, but from what I understand about prisms based lenses, you can not correct for focus and non -uniform stretch or compression is a by- product of bending light using a prism pair...
If you want to go larger, I think you need to go HE, but yes I have tried the VC with my lens. It was interesting. It didn't work out 100% becuase my beam was too wide for the prisms (7.5 x 5.5") that were now standing up on the ends (5.5 x 7.5", so I did get image clip at the sides.
Over all however, it did prove that a HE could be used as a VC if the prisms are large enough.
The key reson I wanted to try this is that I actually need to reduce my screen size from the current 8 foot wide down to about 6 feet. Turning the lens meant that my image width was now the same as the native 16:9 beam, but the height was also now reduced by 33%. At my current seating distance, this worked out to be much better than the larger screen size.
The other thing I found was there was a noticable increase in image brightness from comrpessing the 100% light into a 66% sized screen area.
For me to do this, I will need to source even larger prisms. I have found the prisms I need, but not sure if the supplier can deliver as yet...These larger prisms are 220mm x 180mm...
Mark