DIY anamorphic lens - Page 72

Steve Scherrer · 14th September 2006, 02:50 PM

I was able to make some good progress yesterday. Since I am using two of the same size wedges, I just made a rectangular box from mdf. I actually bought the mdf as precoated shelving--so they are nice and uniform white, with very smooth edges.

I found a good epoxy, and am using brass rivets on the bottom for the point of rotation. These I glued to the bottom of each wedge pretty much in the middle.

On the top, I am using a screw with a 1 inch flat head (don't know what they are called--but the head is very wide), the flat head part will be adhered to the top of the wedge. The screw will traverse a hole in the top of the box, and stick out a little bit over the top. I am using a dial bought from the local hardware store that fits over the shaft of the screw that sticks up through the top of the box.

To lock in the settings, I have a plastic disk that will be glued to the top of the box under the dial. The dial will have a round nub underneath (still figuring out where the nub will come from--I think a small round-head screw in the dial should work). There will be three depressions in the plastic disk so that the nub on the dial will tend to settle in the depressions on the disk. This should be enough to lock in the dial for the pass through, 16:9 and 21:9 settings.

If I have the time, I would like to finish tonight. I'll try to post some pics when I am done.

sdspga · 14th September 2006, 03:50 PM

Quote:

Viewing angles for cinema scope 2.37:1 video will differ slightly to what is excetable (or preferred) for 2.39:1 for film. Where film wants you at or closer than 36 degrees, I think video works the other way. You don't want to be closer then 36degrees at home given the source (DVD) is SD, not HD. HD DVD and or BrD might change this, but for right now, you want to be back a little more, or reduce your screen height which ultimately affects the width.

Sorry, Mark. I was referring to the angles of the prisms to get the correct stretch. I was experimenting and like I said, one can really bend the picture. I am having a little barrelling at the bottom, but really no pinchusioning.

I am hoping you (or anyone else for the matter) can shed some light on what the angles of the prisms should be to correctly stretch the image into the proper AR. Thanks,

scott

Steve Scherrer · 14th September 2006, 06:27 PM

Quote:

Originally posted by sdspga

Sorry, Mark. I was referring to the angles of the prisms to get the correct stretch. I was experimenting and like I said, one can really bend the picture. I am having a little barrelling at the bottom, but really no pinchusioning.

I am hoping you (or anyone else for the matter) can shed some light on what the angles of the prisms should be to correctly stretch the image into the proper AR. Thanks,

scott

If I get this contaption up and running tonight, I should be able to give some pretty exact angle measurements for you.

I don't know, at this point, which angles are ideal--but I foresee that there could be some pretty complicated results--because we have two prisms that could be any angle in relation to a standard (let's say a line across the face of the box, and in relation to each other. Does the optimal angle between the two prisms change depending on the angle of the first prism relative to the projector? IN other words, in these two drawings, both have about the same angle between the prisms, but each one is different relative to the projector. Does that matter? Hopefully, I'll find out...

Mark Techer · 14th September 2006, 11:29 PM

Steve, if you bring in the apex of the front prisms just a touch (mine do touch), I think you have it

Remeber, because the rear prisms's full width is not needed, you can have a slight over lap as well. I found doing this gave better result as well as fitting in to the case I made...

Mark

morkys · 15th September 2006, 02:05 AM

Mark...its me, cpc from AVS

Sounds cool. If these are doable, I would love to try one out myself. I can't read all this now though. Phew!

Bud Bray · 15th September 2006, 02:10 AM

Yep, they're doable! Setting mine up this weekend! Cineplex Odeon has lost a steady customer!

morkys · 15th September 2006, 02:33 AM

...and you may just possibly gain a customer...

that is if one day you will let me drop in with a case of beer to see your contraption in action! I am in Ajax. I travel pretty far for home theatre stuff if its worth it

I want to setup a constant height deal with my Hitachi TX200 so I can view 2.35:1 at full height.

Steve Scherrer · 15th September 2006, 05:02 AM

I got far enough to test the housing with the lenses inside. I epoxied the rivets on the bottom of the lenses, drilled a couple of holes in MDF, put a couple of sides on the box (no top yet) and set it up in front of the pj so I could easily rotate the lenses.

Couple of observations. (Remember--I have a 4:3 projector). With this setup, even with the two small lenses, I can get some significant stretch. One sample I measured at 2.55:1! There is some significant distortion at those stretch levels, and it is really hard to get the geometry correct. I was able to get the top, bottom and left side of the image pretty square, but the right side was significantly bowed. Once I got the image down to about 2.3:1 I was able to decrease the distortion, but not rid it completely. Also, there was significant CA on the sides of the image at these levels. My wife helped me measure the images with a tape measure, and she kept commenting on the "petty colors" on the sides of the image.

Once down to 1.78:1 (which is shown in the following images), I was able to get geometry pretty exact, with no significant CA. The picture was pretty focused all the way across the image.

Would love to play with some test patterns.

Conclusion--2.37:1 is most likely going to be too difficult to accomplish from 4:3, which is too bad. 16:9 from 4:3--easily doable, and the image rivals my panamorph (if not clearer, actually). So going 21:9 from 16:9 projector will be a cinch, and the quality is pretty darn good.

Mark Techer · 15th September 2006, 08:53 AM

Quote:

Originally posted by morkys
Mark...its me, cpc from AVS

Sounds cool. If these are doable, I would love to try one out myself. I can't read all this now though. Phew!

Hi cpc,
The cystal prism discussion starts at about page 60 or 61 but ideally you should start at page 1

Quote:

Originally posted by Steve Scherrer
I got far enough to test the housing with the lenses inside.

Steve, those images are so muchg better than yor other shots. Very well done. I think 33% is all your going to get out of the lens, so 12:9 to 16:9, and then 16:9 to 21:9...

Inertesting that you didn't need to shorten one side of the case. It must just be my very short throw projector...

Mark

dc_pilgrim · 15th September 2006, 11:47 AM

Looking tremendously good guys. I am tempted to order some and I don't even have a pj yet (and have debated going CRT).

Mark, did you wind up ordering any of the US wedges? Just wondering if anyone is going to do a first hand comparison of the Aussie trophy optics to the US trophy optics.

14th September 2006, 11:29 PM	#714
Mark Techer diyAudio Member Join Date: Aug 2005	Steve, if you bring in the apex of the front prisms just a touch (mine do touch), I think you have it Remeber, because the rear prisms's full width is not needed, you can have a slight over lap as well. I found doing this gave better result as well as fitting in to the case I made... Mark __________________ CIH Explained

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14th September 2006, 02:50 PM	#711
Steve Scherrer diyAudio Member Join Date: May 2006	I was able to make some good progress yesterday. Since I am using two of the same size wedges, I just made a rectangular box from mdf. I actually bought the mdf as precoated shelving--so they are nice and uniform white, with very smooth edges. I found a good epoxy, and am using brass rivets on the bottom for the point of rotation. These I glued to the bottom of each wedge pretty much in the middle. On the top, I am using a screw with a 1 inch flat head (don't know what they are called--but the head is very wide), the flat head part will be adhered to the top of the wedge. The screw will traverse a hole in the top of the box, and stick out a little bit over the top. I am using a dial bought from the local hardware store that fits over the shaft of the screw that sticks up through the top of the box. To lock in the settings, I have a plastic disk that will be glued to the top of the box under the dial. The dial will have a round nub underneath (still figuring out where the nub will come from--I think a small round-head screw in the dial should work). There will be three depressions in the plastic disk so that the nub on the dial will tend to settle in the depressions on the disk. This should be enough to lock in the dial for the pass through, 16:9 and 21:9 settings. If I have the time, I would like to finish tonight. I'll try to post some pics when I am done.

15th September 2006, 02:05 AM	#715
morkys diyAudio Member Join Date: Apr 2004 Location: Toronto	Mark...its me, cpc from AVS Sounds cool. If these are doable, I would love to try one out myself. I can't read all this now though. Phew!

15th September 2006, 02:10 AM	#716
Bud Bray diyAudio Member Join Date: Feb 2006 Location: Burlington,Ontario	Yep, they're doable! Setting mine up this weekend! Cineplex Odeon has lost a steady customer!

15th September 2006, 02:33 AM	#717
morkys diyAudio Member Join Date: Apr 2004 Location: Toronto	...and you may just possibly gain a customer... that is if one day you will let me drop in with a case of beer to see your contraption in action! I am in Ajax. I travel pretty far for home theatre stuff if its worth it I want to setup a constant height deal with my Hitachi TX200 so I can view 2.35:1 at full height.

15th September 2006, 05:02 AM	#718
Steve Scherrer diyAudio Member Join Date: May 2006	I got far enough to test the housing with the lenses inside. I epoxied the rivets on the bottom of the lenses, drilled a couple of holes in MDF, put a couple of sides on the box (no top yet) and set it up in front of the pj so I could easily rotate the lenses. Couple of observations. (Remember--I have a 4:3 projector). With this setup, even with the two small lenses, I can get some significant stretch. One sample I measured at 2.55:1! There is some significant distortion at those stretch levels, and it is really hard to get the geometry correct. I was able to get the top, bottom and left side of the image pretty square, but the right side was significantly bowed. Once I got the image down to about 2.3:1 I was able to decrease the distortion, but not rid it completely. Also, there was significant CA on the sides of the image at these levels. My wife helped me measure the images with a tape measure, and she kept commenting on the "petty colors" on the sides of the image. Once down to 1.78:1 (which is shown in the following images), I was able to get geometry pretty exact, with no significant CA. The picture was pretty focused all the way across the image. Would love to play with some test patterns. Conclusion--2.37:1 is most likely going to be too difficult to accomplish from 4:3, which is too bad. 16:9 from 4:3--easily doable, and the image rivals my panamorph (if not clearer, actually). So going 21:9 from 16:9 projector will be a cinch, and the quality is pretty darn good.

15th September 2006, 11:47 AM	#720
dc_pilgrim diyAudio Member Join Date: Sep 2006	Looking tremendously good guys. I am tempted to order some and I don't even have a pj yet (and have debated going CRT). Mark, did you wind up ordering any of the US wedges? Just wondering if anyone is going to do a first hand comparison of the Aussie trophy optics to the US trophy optics.

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