DIY anamorphic lens

[pinkmouse]

Originally posted by MikeP
Tonight I'm going to test and see if it's coming from the screen reflecting back onto the prisms (I have a white screen).

Unlikely, I would have thought. Think how much the light has been attenuated from it's journey from the lens, (admittedly dispersion controlled), bouncing back of the screen, (diffuse, therefore square/cube law applies) then back off the relatively tiny prism surface, (again, non directional). That's got to be a pretty tiny amount.

[Bud Bray]

Originally posted by pinkmouse
If the results are an improvement, you might want to think about doing the top and bottom of the prisms as well...

I have the tops & Bottoms covered with black tape...it holds the two together. So all is covered except the 2 faces. Some day soon(when I have time) i'm going to do a mask for the faces to just allow the PJ beam thru. See if it makes a difference.
Bud

[Mark Techer]

Bud,

I think it will. Take a look at Prismasonic's prisms holders - small rubber attachments that go right around the prisms.

And ISCO III has a plate at the back (psrt of the mounting system) that restricts the width of the rear optic...

Mark

[slothuk]

Hi, I am new to this topic and spent all last night reading from page 1!

What I was wondering is, if any of you have come across anywhere to get these glass wedges in the uk, or if any of the companies previously used will ship internationally as im having difficulty locating these here!

Thanks.

[roar]

You could email mfg directly and see if they ship to any distributors in the UK. That is what I did to get them here in Canada without having to pay duty or shipping charges from the states.

[Mark Techer]

Originally posted by slothuk
Hi, I am new to this topic and spent all last night reading from page 1!

I wish Tor Arne would come back. I often go over his posts from the beginning as he was very knowedgeable about this. In fact the idea of solid prisms are discussed there as well, just no one did anything about them...

It would be really cool to see his knowledge applied to SOLID CYRSTAL PRISMS where liquid leaking is not as issue...

Mark

[morkys]

Ok, here are my screen shots. I finally took down my 16:9 screen and put up a big sheet of blackout material to start working on a prism lens. My first lens is a two prism lens. The shots show bad angle from me lying on the futon and there is camera shake. Still, here they are:

C3P0 and R2



R2



Rebel B4 Darth Enters



C3 P0 on Tatooine



Leia



..and there you go. Again, another group of screen shots from the beginning of an adventure. Not mucn masking in this ghetto setup except for a board on top and a sheet of my left over velvet-ish masking material. I wanted to try it without much fuss so I simply put a board under-neath my projector:



...and put the prisms out in front. I may put the projector and lens on the same surface, but not before leveling everything. I measured the 16:9 projected image alone and then calculated 33% stretch divided by 1/2 and setup points on the left and right and stretched until I fit the new 2.37:1 shape.

I noticed that there was a huge amount of reflections to the side and the back and on the screen. I noticed that I didn't care much about the curved edges of the screen. I noticed that I didn't like that it looked as though the stretch may not not be uniform, and rotating pans showed varying degree of stretch. I noticed that although there may have been Chromatic Aberations and or poor focus to the sides, I didn't see that much.

The geometry is poor with the sides because the whole contraption is angled down (notice that the sides are wider at the bottom).

I have much work to do, but at least it is a start. I will try to build a box of sort, and/or start sanding and blacking out all the sides of the lens that are not used (top, bottom and sides). I guess I can try a 4 prism setup eventually.

I will take more photo's from a tripod as I progress. Thanx to all here who have helped. This is an interesting ride

[Mark Techer]

Nice geometry

That R2 shot looks great, as does C3PO's round tummy thing. Good to see that your CA is small and limited to the sides. That Rebel solder looks very good...

So is that just from 2 J series prisms?

Well done Morkeys

Mark

[morkys]

Yep. I used two medium prisms. I can no longer edit the post so the grammer mistakes will have to stay I guess...

In terms of my overall impression of the test, I was most disappointed with the reflections, lack of lumens and poor contrast in dark scenes. Since the low lumens and poor contrast are mostly due to the light lost to reflections, I am disappointed that the lens reflect so much. Whatever we do, this is light that will be lost from the projector, even once I block it from hitting the walls and screen.

Reflections were so bad that dark contrasty scenes were terrible with flares and reflections everywhere. Of course, with no masking anywhere, that is how it goes. I think the one big drawback of these prisms is not the focus and geometry, but that even with masking, we are probably loosing lots of light due to reflections. It would be nice to have a surface that doesn't reflect or absorb too much light, and passes as much of the light through as possible.

I was most impressed with the overall focus across the screen. The scene where Jason looks at all his fake identity passports and credit cards etc in Bourne Identity, the text looked quite sharp to the sides. It looked fairly good. Bright scenes really look good.

If anybody finds an anti-reflective coating solution, let us know

[Bud Bray]

Hey, looks pretty good so far. It's a constant tweaking experience...enjoy the ride! You probably have to angle them downwards more than you have to square up the sides better(watch they don't fall, i've broken 4 so far), Use duct tape to hold them down till you get a housing built(once you have the angles where you want them, also good to mask end reflections)
Looks good so far!
Bud