DIY anamorphic lens

[morkys]

Sweet. Sounds good. I am just getting an iScan HD+ upgrade from my iScan Ultra so I can do dvd's with aspect ratios like 2.0:1 (Apocalypse Now) and 2.20:1 (Tron) using some sort of lens or prism. Since the lens/prisms that I can afford only manage 1.33 or 1/3 I cannot do anything between 1.78:1 and 2.35:1 properly but with the HD+ I will have custom aspect ratio control. Anyways, I also want the scaling abilities of the HD+ etc. Now I just need a Panamorph or these Prisms.

Do they have different sizes? What do I need? Is there a post back a few pages I need to read?

My projector is a Hitachi PJ TX200 and it sits 152" from the screen which will be 48"high x 112.7" wide (2.35:1). The TX 200 has a 1.6:1 zoom. My projector seems to be farther away than average. My projector is at 1.15x zoom. (Right now my screen is 47" x 83.5" but thats the current 16:9 shape).

The other cool thing for now at least, is that I am using almost zero lens shift. I think that is good. My projector is shooting the image at the screen practically dead centre.

Which prisms do I buy?

thanx in advance for further info,

Chris

P.S. BTW - the problems with geometry are possibly to do with your projectors alignment. Normally you aim your projector as square as you can but even if you don't aim it totally perfect, you don't notice any geometry issues. Trouble is, when you use a lens that expands the image, geometry mis-alignments of the projector are magnified. Make sure your projector is aimed at the wall as squarely as possible. Also make sure your screen is square. Of course these are both relying on each other. Don't assume your screen is mounted squarely on the wall, and don't assume your wall is square, and ultimately don't assume your projector is shooting square. Check it all out. And by square, I mean perpendicular vertically and horizontally.

Good luck folks...this is an exciting adventure to follow. I hope to join the ranks asap

[Mark Techer]

Originally posted by morkys
Sweet. Sounds good. I am just getting an iScan HD+ upgrade from my iScan Ultra so I can do dvd's with aspect ratios like 2.0:1 (Apocalypse Now) and 2.20:1 (Tron) using some sort of lens or prism. Since the lens/prisms that I can afford only manage 1.33 or 1/3 I cannot do anything between 1.78:1 and 2.35:1 properly but with the HD+ I will have custom aspect ratio control. Anyways, I also want the scaling abilities of the HD+ etc. Now I just need a Panamorph or these Prisms.

One you get the lens, you customise all ARs with the scaler. What will happen for odd ARs like 2.20:1 or 2.0:1 is that you will not use the full horizontal rez, becuase you want (need) to keep the vertical full, then squeeze the width in a touch...

Mark

[morkys]

Exactly. I cannot do that with the iScan Ultra and the iScan HD doesn't do that either. I need the HD+.

I still don't understand which prisms to buy. I need to buy 4 prisms right? I can build a housing for them no problem.

[Bud Bray]

Originally posted by morkys
Exactly. I cannot do that with the iScan Ultra and the iScan HD doesn't do that either. I need the HD+.

I still don't understand which prisms to buy. I need to buy 4 prisms right? I can build a housing for them no problem.

4 prisms give a better picture than 2, but it's up to you really.
The medium size ones should work but you really should do the paper test 1 foot from the lens to see how large the beam is.

[morkys]

So I don't have to request any specifc shape/angles? I just chose a size based on my projectors beam size at about 1 foot in front of the projector? Are the large ones large and heavy enough to cause any practical difficulties?

Here are some questions I really need answered in order to understand this process properly:

0) Are we doing HE or VC here? Which works for best results? Is it possible I may need to chose one over the other based on my projector zoom/throw etc?

1) Let's assume I am doing Horizontal Expansion, how do I achieve the approximate 1.33x optical stretch? Is it just a matter of the angles of the prisms?

2) I used to think that the angle/shape of the prism and its faces determines the stretch etc, but is that not necessarily true? Are you guys just using these lens and chosing the angle of alignment to get your image? The shape of the prism doesn't matter or these just happen to be nearly perfect for this purpose? Could you vary the angles in order to make things work for 2.0:1 and 2.20:1?

3) Should I make a 2.37:1 screen?

I am willing to get 4 prisms if that produces the best results. I will do the paper in front of the lens test today and order the prisms asap. I am re-arranging my room today to accomodate a new screen and hopefully by Monday night I will close a deal on an iScan HD+.

CIH here I come

P.S. Bud, as a Canadian, can you help with the ordering of the prisms?

email me:
morkys@hotmail.com

[Bud Bray]

Originally posted by morkys
So I don't have to request any specifc shape/angles? I just chose a size based on my projectors beam size at about 1 foot in front of the projector? Are the large ones large and heavy enough to cause any practical difficulties?

Here are some questions I really need answered in order to understand this process properly:

0) Are we doing HE or VC here? Which works for best results? Is it possible I may need to chose one over the other based on my projector zoom/throw etc?

*HE, your PJ should be able to do the vertical stretch.


1) Let's assume I am doing Horizontal Expansion, how do I achieve the approximate 1.33x optical stretch? Is it just a matter of the angles of the prisms?

*YES

2) I used to think that the angle/shape of the prism and its faces determines the stretch etc, but is that not necessarily true? Are you guys just using these lens and chosing the angle of alignment to get your image? The shape of the prism doesn't matter or these just happen to be nearly perfect for this purpose? Could you vary the angles in order to make things work for 2.0:1 and 2.20:1?

*YES

3) Should I make a 2.37:1 screen?

*Yes

I am willing to get 4 prisms if that produces the best results.

*You can get by with 2 but have more CA...virtually gone with 4

I will do the paper in front of the lens test today and order the prisms asap. I am re-arranging my room today to accomodate a new screen and hopefully by Monday night I will close a deal on an iScan HD+.

CIH here I come

P.S. Bud, as a Canadian, can you help with the ordering of the prisms?

*I just phoned them in the US, spoke to Suzanne and ordered them.

email me:
morkys@hotmail.com

[Steve Scherrer]

Originally posted by morkys
So I don't have to request any specifc shape/angles? I just chose a size based on my projectors beam size at about 1 foot in front of the projector? Are the large ones large and heavy enough to cause any practical difficulties?

Here are some questions I really need answered in order to understand this process properly:

0) Are we doing HE or VC here? Which works for best results? Is it possible I may need to chose one over the other based on my projector zoom/throw etc?

1) Let's assume I am doing Horizontal Expansion, how do I achieve the approximate 1.33x optical stretch? Is it just a matter of the angles of the prisms?

2) I used to think that the angle/shape of the prism and its faces determines the stretch etc, but is that not necessarily true? Are you guys just using these lens and chosing the angle of alignment to get your image? The shape of the prism doesn't matter or these just happen to be nearly perfect for this purpose? Could you vary the angles in order to make things work for 2.0:1 and 2.20:1?

3) Should I make a 2.37:1 screen?

I am willing to get 4 prisms if that produces the best results. I will do the paper in front of the lens test today and order the prisms asap. I am re-arranging my room today to accomodate a new screen and hopefully by Monday night I will close a deal on an iScan HD+.

CIH here I come

P.S. Bud, as a Canadian, can you help with the ordering of the prisms?

email me:
morkys@hotmail.com

It's my experience that the angles of the prisms themselves don't really matter all that much, as long as they are prisms (in other words, the angle of the prisms itself, not the angles of the prisms relative to each other and the projector.)

I believe, without having done the math (not even sure how to do the math), that the influence of the angle of the prisms themselves, and the prisms relative to each other give you the stretch needed. So if you have a greater angle in your prism (like Mark), your prism angles relative to each other don't need to be as extreme. If you use smaller angle prisms (like from Massillon, which is measured at 5 deg.), then you have to increase the angles of the prisms relative to each other. So any prisms will work, you just have to find the right angles relative to each other then.

This is horizontal expansion, as opposed to vertical compression. Either way, though, you will have to get your projector to do the stretch to fill the panel.

[roar]

Any Canadians looking to order may want to hang on for a bit, I'm waiting a call back from someone in Ontario who may be able to get them. After talking to Bud and hearing that he got dinged the UPS 'Brokerage Fee', I thought i'd look into a Canadian distributor.

I emailed the actual manufacture of the wedges and she gave me a list of their Ontario distributors. I've contacted one of them and they are going to get back to me on a price. They said they wouldn't place the order for just the 4 wedges I wanted but would likely have an order in the next month I may be able to 'piggy back' onto so to speak... so when I get a price from these guys maybe others would want to join in to try and avoid some of the duty/brokerage fees associated with cross border purchases.

[morkys]

Thanx Bud and Steve, that is Perfect info. Roar, thanx for the offer regarding the Prisms within Ontario.

So I can take a movie with a 2.0:1 or 2.20:1 spect ratio, or any other aspect ratio between 1.78:1 and 2.37:1 and using my video processor (or projector..but its a pain) I stretch it to fill the 16:9 panel and then I just have to vary the angle of the prisms relative to one another in order to project an image with the correct aspect ratio of the dvd? Is this correct? If this is true, then this is awesome!

Roar, I am totally in for prisms from within Ontario. Being a country full of sports events, we must have plenty of access to prisms for trophies and awards. There are probably others, but you did the best by sticking with the same product, but hopefully sourced within Canada.

NEVER use UPS when ordering from anywhere. UPS charges horrible brokerage fees. When ordering from the US, I always go with USPS. Does the trick every time. Within Canada, or shipping to the US, I use Canada Post

(If it doesn't work out within Canada, we could always get a local to buy the prisms and ship them to us There must be somebody out there near the distributor. Just a thought)

[morkys]

roar,

Any word yet from the local Ontario distributor of the prisms?