All other things being equal, and disregarding the ability to use the lens one builds will other projectors, for a given projector, is it better to use prisms bigger than you need or should you get the smallest prisms that will work?
Donny, I think you will be fine with the smaller prisms. I have a Infocus 7205 which I think has a similar lens diameter to the HD72 and the smaller prisms work just fine with it, with plenty of room to spare. The small prisms also worked for my old PLV-60 (which has a much larger lens), although just barely.
What I would highly suggest is that you get a couple of prisms, then play with them in front of your projector just sitting on a coffee table or something. This will give you a feel for the geometry.
As Mark said, it's not just the depth that you need to worry about. With the large vertical offset of the Optoma projectors, you might need more tilt that we do in order to get the geometry looking nice and square. And if you made your sofit too large, then you might get the light beam coming out of the lens hitting the edge of the sofit.
Since every setup is a bit different, you'd probably save yourself a lot of agony to get the prisms and do some trial setups.
Another question you'll want to ask is whether you want the prisms to be removeable. For example, I often hook my PC up to the projector to play games on the big screen, and I don't want my desktop stretched. And if I use the projector scaler to shrink the picture to compensate for the anamorphic lens stretch, then I loose resolution and it makes the text on the desktop harder to read. So for PC applications, I want to remove the lens, so I'm building a sliding enclosure.
So, lots of stuff to think about and play around with before you do any final construction that might be hard to change.
What I would highly suggest is that you get a couple of prisms, then play with them in front of your projector just sitting on a coffee table or something. This will give you a feel for the geometry.
As Mark said, it's not just the depth that you need to worry about. With the large vertical offset of the Optoma projectors, you might need more tilt that we do in order to get the geometry looking nice and square. And if you made your sofit too large, then you might get the light beam coming out of the lens hitting the edge of the sofit.
Since every setup is a bit different, you'd probably save yourself a lot of agony to get the prisms and do some trial setups.
Another question you'll want to ask is whether you want the prisms to be removeable. For example, I often hook my PC up to the projector to play games on the big screen, and I don't want my desktop stretched. And if I use the projector scaler to shrink the picture to compensate for the anamorphic lens stretch, then I loose resolution and it makes the text on the desktop harder to read. So for PC applications, I want to remove the lens, so I'm building a sliding enclosure.
So, lots of stuff to think about and play around with before you do any final construction that might be hard to change.
I see no reason to use larger prisms than you need. There is no impact on picture quality that I can determine. And I'd rather have a lighter lens...even the small prisms are heavy.morkys said:
The throw ratio is 1.5-1.9. I'm using it with no zoom, but I don't understand the correlation well enough to know which end of the range that puts me at.
I have the HD72...you need the medium size prisms at least. You CAN use the small ones for the FIRST prism but you NEED a medium for the second. I have both and the output size is using all but 1 inch on my medium outer one(my screen is 51x124). I can't see a smaller screen being that much of a difference tho.
Side note. Went back & tried the 2 prism set(going to have BOTH 2&4 in housings so I can swap them out). CA much more noticable(to me anyway) with the 2, but extra reflections lessened. Did have annoying reflection still on right with CARS(what IS IT with that movie?).
Watched Superman Returns...is it just me or is that movie REALLY dark and colourless? It seemed dark & washed out for most of the picture. I have the PJ WELL withing the distance to screen and other movies blind you.
Still have to work on the housings...the edge Mark cuts off on the right is tricky, if you cut too much off, you get nasty reflections, if you don't cut enough, it cuts the right side off of the picture...somewhere there's a "SWEET SPOT" & i'm gonna find it!
Overall, I still prefer the 4 prism set up...yes, more reflections but I personally find it's a better picture, just my opinion.
Damn Christmas is screwing up my theatre time...BAH HUMBUG!
Bud
Side note. Went back & tried the 2 prism set(going to have BOTH 2&4 in housings so I can swap them out). CA much more noticable(to me anyway) with the 2, but extra reflections lessened. Did have annoying reflection still on right with CARS(what IS IT with that movie?).
Watched Superman Returns...is it just me or is that movie REALLY dark and colourless? It seemed dark & washed out for most of the picture. I have the PJ WELL withing the distance to screen and other movies blind you.
Still have to work on the housings...the edge Mark cuts off on the right is tricky, if you cut too much off, you get nasty reflections, if you don't cut enough, it cuts the right side off of the picture...somewhere there's a "SWEET SPOT" & i'm gonna find it!
Overall, I still prefer the 4 prism set up...yes, more reflections but I personally find it's a better picture, just my opinion.
Damn Christmas is screwing up my theatre time...BAH HUMBUG!
Bud
Donny if your using the smallest image size, then your at 1.9TR. If zooming the image to the max, thyour at 1.5. Basically the width of the 16:9 divied into the projection distance gives the thrwo ratio...DonnyBahama said:
I have not seen the DVD, but the film was dark in the cinema. His cape is almost a brown and not the bright red it was in the earlier films...
I actually took a close look at that image and found two things -
1. that there is almost 2" of black between the edge of the picture and the edge of the frame and
2. the reason it looks CUT OFF is that most of that 2" is actually projected onto the masking as my screen is 235 not 237, so in order to keep the geometry correct, I have to shoot the image off the edges.
Mark
where to buy prisms
Hey Roar,
New to the forum so it won't allow me to PM you. Just looking for the list of Canadian distributers. Looking to buy my first PJ and want to do CH. It would be best if I could come up with source and cost of the prisms so I could budget that in to my total system price. My wife has helped me set a realistic limit.
Thanks
Hey Roar,
New to the forum so it won't allow me to PM you. Just looking for the list of Canadian distributers. Looking to buy my first PJ and want to do CH. It would be best if I could come up with source and cost of the prisms so I could budget that in to my total system price. My wife has helped me set a realistic limit.
Thanks
I didn't study the image I projected. I suppose there is probably some Chromatic Aberations, but for now I may still work on a two prism setup. If you are doing a 4 prism setup, you really should try to source 2 prisms that are equal in angle to the 2 prisms you put together in each set of 2 in your 4. That way you will probably eliminate the reflections. (I actually want new glasses because of CA. My glasses produce CA away from the centre of my lens. I get tiny violet and blue fringing which is sometimes noticable on lighter coloured bright objects. I bet if I never read camera reviews I wouldn't have known what it was. It's not horrible but I would like to eliminate it. My vision is otherwise 20/20 however. Unless I find the CA is more than a pixel, or looks worse than what I see through my glasses, then I may be happy with a 2 prism setup for now, until I can find larger angle prisms.)
I am thinking of sanding and otherwise roughing up the four non optical-path sides of each of my two prisms. Afterwards, I may paint the 4 sides the flatest black I can find, or perhaps I should just leave it. Next, I may get my black felt like material and mask down the prisms a little more. Finally, I will build an enclosure of sorts, hopefully one which allows me to adjust for varying aspect ratio film dvd's. Lastly I will have to align the DIY contraption in front of my projector.
Can anybody think of a reason why I should not sand or rough up the 4 non face sides of my two prisms? Should I paint them a flat black even if it just means using a black paint marker?
If I sand them, what should I use?
If I paint them, what paint should I use?
I am going to do some research. Feel free to provide feedback.
thanx,
Chris
I am thinking of sanding and otherwise roughing up the four non optical-path sides of each of my two prisms. Afterwards, I may paint the 4 sides the flatest black I can find, or perhaps I should just leave it. Next, I may get my black felt like material and mask down the prisms a little more. Finally, I will build an enclosure of sorts, hopefully one which allows me to adjust for varying aspect ratio film dvd's. Lastly I will have to align the DIY contraption in front of my projector.
Can anybody think of a reason why I should not sand or rough up the 4 non face sides of my two prisms? Should I paint them a flat black even if it just means using a black paint marker?
If I sand them, what should I use?
If I paint them, what paint should I use?
I am going to do some research. Feel free to provide feedback.
thanx,
Chris
Testing The Aussiemorphic Lens
All lenses will have some CA, it is just the amount that varies.
Yesterday I had the oppertunity to run my lens, The "Aussiemorphic Lens" upagainst Prismasonic's H600 and H1200.
In all, testing ran for about 9 hours, so this wasn't just a case of a quick look infront of a different projector, but a true indication of the potential of this very simple and affordable design.
The projector was a high end SHARP 720 DLP and was fed 1080P from HTPC and running through a "Realto" scaler, so some serious toys here guys, a far cry from anything I have...
The TR was 2.2, projected on to a 3m wide "scope" screen and the results were noting short of gobsmacking. There was no pincushion at that range, and CA that was present was only at the edges to about about 1/8 screen with in which we tested with both a grid of white lines on black as well as with text from the PC. The focus uniformity was exceptional from corner to corner, the "Aussiemorphic Lens" surprized me in the way it was able to resolve readable text from edge to edge as well.
The testing included calibrating the projector with the "Aussiemorphic Lens" and then changing it out with one of the Prismasonic lenses to see if there was any values changes. In most cases, there were none, and I was extremely releaved to see that colour saturation was not being affected with the "Aussiemorphic Lens". Generally contrast and black levels were constant as well.
The H1200 did have some advantages (a 4 prism full coated lens at almost 12 times the price), but it was too close to call for the H600 (2 prism lens).
The lens flare is virtually non exsistant at that TR as well (and I was looking for it), so not bad for non-coated prisms 🙂
A very big thankyou to Matt for your time and theatre use 🙂
I am very impressed...
Mark
All lenses will have some CA, it is just the amount that varies.
Yesterday I had the oppertunity to run my lens, The "Aussiemorphic Lens" upagainst Prismasonic's H600 and H1200.
In all, testing ran for about 9 hours, so this wasn't just a case of a quick look infront of a different projector, but a true indication of the potential of this very simple and affordable design.
The projector was a high end SHARP 720 DLP and was fed 1080P from HTPC and running through a "Realto" scaler, so some serious toys here guys, a far cry from anything I have...
The TR was 2.2, projected on to a 3m wide "scope" screen and the results were noting short of gobsmacking. There was no pincushion at that range, and CA that was present was only at the edges to about about 1/8 screen with in which we tested with both a grid of white lines on black as well as with text from the PC. The focus uniformity was exceptional from corner to corner, the "Aussiemorphic Lens" surprized me in the way it was able to resolve readable text from edge to edge as well.
The testing included calibrating the projector with the "Aussiemorphic Lens" and then changing it out with one of the Prismasonic lenses to see if there was any values changes. In most cases, there were none, and I was extremely releaved to see that colour saturation was not being affected with the "Aussiemorphic Lens". Generally contrast and black levels were constant as well.
The H1200 did have some advantages (a 4 prism full coated lens at almost 12 times the price), but it was too close to call for the H600 (2 prism lens).
The lens flare is virtually non exsistant at that TR as well (and I was looking for it), so not bad for non-coated prisms 🙂
A very big thankyou to Matt for your time and theatre use 🙂
I am very impressed...
Mark
Ok, so did you do anything to the ends of those prisms besides block out reflections? You didn't sand or paint the top, bottom and sides of the prisms to prevent reflections?
morkys said:
I used the diamond stone to take the shine off the small ends (don't really think it made a difference) and also am now using a black case...
Just a quick note - the Prismasonic prisms are not blocked off on their sides either. I could see the tops of them on the H600 and they were smooth and shiny like ours. They use a metal housing to hold the prisms in place, but they have multi coated prisms...
Mark
Ok, so it didn't make a difference (or not enough to notice) to yours because you block the reflections, and the primasonic is coated. Ok, I can't see any harm in sanding/roughing up the sides, top and bottom before painting them black.
All we need to do is find out where to get these coated for not too much money...and/or where we can find larger angle prisms that are equal in angle to two of ours put together, and whether or not we can source any prisms already with coating. Anybody with time during the day, do some research for us. I will try to check around, but I work days and am not home before most north american businesses on the mid to east coast are closed.
All we need to do is find out where to get these coated for not too much money...and/or where we can find larger angle prisms that are equal in angle to two of ours put together, and whether or not we can source any prisms already with coating. Anybody with time during the day, do some research for us. I will try to check around, but I work days and am not home before most north american businesses on the mid to east coast are closed.
morkys said:
No painting or taping or using a case simply stops light exiting the prisms from another face other then the main ones...
morkys said:
I'm looking into that, but as for the angles, I don't really think it makes a lick of difference - the angles of the front and rear faces seem to be the same regardless of the prisms' angles. Having a thicker prisms simply adds more weight. You guys have had great success with just 10 degree prisms and I have had great success with a steeper angle, but in the end, they both do the same job...
Mark
Re: Testing The Aussiemorphic Lens
This is exactly what I hoped someone would do. Glad to hear it went so well. Any photos?
Mark Techer said:
This is exactly what I hoped someone would do. Glad to hear it went so well. Any photos?
No time for that - soffits go up today.MikeP said:
Thanks for the heads up on that.
I will be using an HTPC, outputting 1280x768 to match the native rez of the projector. I believe the HD72 gives me the ability horizontally compress even a 16:9 image, so that - even with the lens in place - I'd be projecting a pillar-boxed, non-compressed image. (Maybe Bud can confirm this.)
Thanks so much for the definitive answer, Bud! As it turns out, it looks like the lens may end up mounted to a hinged panel/door next to the projector. With the door closed, the lens will sit inside the soffit, unseen. With the door open, it the lens will sit in front of the projector lens, though there may be a little more of a gap between the projector and the lens assembly than there would otherwise be, so it looks like I should probably go medium on both lenses.Bud Bray said:
Bud- did you have to tilt your lens assembly (to compensate for the HD72's vertical offset?) If so, is this a significant design issue?
Re: Testing The Aussiemorphic Lens
Wow! Outstanding! The "Aussiemorphic Lens" is a two prism lens, isn't it?Mark Techer said:
DonnyBahama said:
I have wondered this myself. What about adding a piece of glass with anti-reflective coating on each prism face?
Re: Re: Testing The Aussiemorphic Lens
Not at this time, but I will be re-visiting that HT on the 27th and I will be taking Foghorn17 as a witness 🙂 so I will try get some snaps then...
Yep, bare bones and basic with just two prisms 🙂
This is worth looking into but it will add severe weight and may cause the case size to be larger as well - something I am not keen on...
Yes, so for a 2 prism lens you will need 4 peices of antireflective glass...
Mark
Steve Scherrer said:
Not at this time, but I will be re-visiting that HT on the 27th and I will be taking Foghorn17 as a witness 🙂 so I will try get some snaps then...
DonnyBahama said:
Yep, bare bones and basic with just two prisms 🙂
DonnyBahama said:
This is worth looking into but it will add severe weight and may cause the case size to be larger as well - something I am not keen on...
Steve Scherrer said:
Yes, so for a 2 prism lens you will need 4 peices of antireflective glass...
Mark
