DIY anamorphic lens

[Mark Techer]

Originally posted by morkys
What about placing a final sheet of anti-refective and polarized glass after the prisms/lens?

Now I did try this in front of the front prisms which reduced these unwanted reflections by at least a further 30%, meaning that only the very worst (say the THX logo for example) reflections were visible. It adds a lot of extra weight to the lens though for some, but not a total fix...

Originally posted by Bud Bray
I was thinking between the prisms...

The pieces of anti-reflective glass I had samples of were just too big to go inbetween the prisms, but given that I was still thinking about reflections being from the screen, this is worth persuing once again...

Originally posted by morkys
I think you want the anti-reflection/polarizer after the last stage of prisms/lens because otherwise, there is no garantee that some stray reflection is somehow getting through. Plus its easier to simply add it at the end and allow for you to keep whatever fixed or adjustable prism configuration you already have. It could work between prisms, but you'd have to figure out between which prisms, the individual paired up? Between the sets of prisms or what? May as well just do it at the end of the chain, although you can always try different locations. It's just a thought. I figure if a polarizer can reject reflections from the surface of water and windows when taking photo's, it make work ok in this application too. As usual, one never knows until it's tried out.

I would think that you might bond the anti-reflective glass to one of the prisms - even using small dabs of hot glue from a hot glue gun to hold them in place. That way you align the prisms, you also position the A-R glass...

Originally posted by morkys
Anybody have a clue where we could find a polarized and anti-reflective coated peice of glass not too much bigger than one of these prisms that won't otherwise negatively affect the image or drop lumens too much?

I used a product (but ditched the samples when I moved ) called "clear view" which is a laminated glass product - glass/plastic/glass. It has just 9% (?) reflectivity instead of the usual 20% of standard glass.

What I want to know is that if they can coat full sheets of glass, then why can thy not coat our prisms with the same stuff?

Also because the glass is a different product to that of the prisms, it might be the achromatic solution we really need as well...

Mark

[Mark Techer]

Hi Bud and other guys living in Canada...

I have been getting quite a few inquiries about my lens which, whilst I am selling as DIY kit here, am not exporting to the US or Canada at this time. You guys able to supply prisms to those interested if I send you their details?

Mark

[Bud Bray]

We have the contact # for a Canadian supplier for the prisms. For US customers, they can contact the US supplier, we have that # too and it's posted (post 734) a few pages back in this forum.

Bud

[Mark Techer]

Good stuff, thanks Bud...

Mark

[Mark Techer]

It was brought up recently about unwanted reflections from the prisms, where Bud Bray seems to have identifed the problem as stray light between the prisms that then hits the screen.

We agreed that the worse case senario might be a black screen with bright images such as the THX logo or maybe some text, but check these out...





With the exception of the small "light smear" near the T, note there are no green streaks

Mark

[artbypaul]

Awesome Mark! Great looking shots!

I readjusted my lenses and made sure they were basically touching and centered with lens to get the proper geometry on the screen and I'm no longer really seeing much stray reflecting on the image.

What I don't understand is how RANDOM it is... Often times scenes that should show the annoying reflections show absolutely nothing, then later in the film the same lighting situation occurs (dark scene with a small brightly lit object on the right side of the screen) and it shows as a reflection!

It's almost like these prisms are mocking me! Like they're saying, "Remember, this is home made! " LOL! Or maybe more appropriately, "Don't be so proud of this technological terror you've created..."

[Mark Techer]

Thanks for the feedback, here and AVS

Yeah it is strange alright. The other day, I had green streaks right across the screen that I have never seen before. I took out the lens, and re-installed it, and the streaks were gone. I can not explain that at all.

When I hand snapped these images this afternoon, I didn't even pause the disc, as I was hoping to capture some element of green streak, but nothing.

If you click on my web thing you can see my latest BLOG update which has a new CIH Explained section with photos...

Mark

[artbypaul]

I just checked out your latest blogs, Mark. Nice explanation of CIH, and it's nice to see you're up and running again at your new place.

[Mark Techer]

Is it easy enough to understand?

I have been asked by a few people in the HT industry to explain CIH, and it is a technical topic to the newbie.

So I wanted a site where I could direct people to have a look and read, but not give them hours of reading. And hopefully the images tell most of the story and explain the "why"...

Mark

[artbypaul]

Yes, your explanation is to the point and easy to understand in my opinion. I agree, while it seems to be fairly elementary, I find myself having to explain repeatedly to some of my friends and family how the whole thing works. Next time they ask, I'll just send them to your blog!