DIY anamorphic lens

[morkys]

What you talkin about Willis?

Are you asking me how far the prisms are? What prisms?

[Mark Techer]

I figure I could use the 752 while I wait for the prisms to arrive

Not sure if I read this right, but it sounded like you have prdered some prisms, but also want to buy a commercial lens - Panamorph 752...

Mark

[morkys]

Yes, I have "orded" prisms to be coming by way of roar's order. I have been searching for a Panamorph 752 and somebody has offered me one. I figure I may pick it up now and start my setup. When the prisms get here, I can hopefully make a cheaper but more tweakable DIY lens that will have optical quality as good or better than the Panamorph 752. The 752 can act as a measuring stick of sorts. May offer less for it though, so I won't lose too much if and when I sell it after I make my own lens. If the seller doesn't want to sell for my offer then I will keep waiting for the fun-for-the-whole-family prism adventure whenever we get those crazy things

If by "how far away.." you mean how long before I get them, ...I don't know. Roar has been hard at work trying to get an order moving from a Canadian distributor, but it may take a while longer. Maybe another month? What say you roar? How much longer you figure?

[Bud Bray]

Just got an email from ROAR, says bout 2 weeks.

[morkys]

Oh, that's cool. Hmmmm...maybe I will hold off on the Panamorph. We'll see

[roar]

Well that 2 weeks is being optomistic I've got a call into the friendly people there, the lady I've been dealing with doesn't work Monday's and Friday's I believe, I'll update you when I've got more info

[Bud Bray]

But you PROMISED! *grin*

[Mark Techer]

Did some testing tonight...

My theory was based on the alignment of the prisms - that the lens can be used for multiple aspect ratios if turned and rotated.

As it turned out, my projector's very short throw prevented my experiment from working 100%, but gave me the proof that I needed to answer some questions that have been asked here and not answered...Yes those wanting a VC can do so if you build the HE first, then turn and flip the lens...

With the prisms aligned as shown in my blog, the lens is a Horzontal Expanding lens.

Turn the lens 180 degrees, and the opposite happens as the lens now becomes a Horizontal Compression lens.

In my current set up, I am too close to the screen to be able to enjoy films as much as I could in the larger room of the house I recently sold. The projector/lens set up works to fill the screen, but I am too close.

I turned the lens around as well as flipped it on to its side. What I found was that the HE now did become a VC with correct geometry, but the prisms which are 5.5" high are now 5.5" wide and are too small for my set up in this mode. The sides of the image were clipped hard.

If I was to build a lens with wider prisms, I might be able to achieve the results I was chasing, or change my projector for a unit with a longer throw, where the latter will not be happening for some time...

Something very interesting about the VC, the image brightness actually goes up, and the pixel structure is less visible...

I wish I could comment on the sides, but they were being clipped...

Mark

[dc_pilgrim]

Mark,

Based on your experiments, is it best to go for as big a prism as possible to give oneself HE vs VC flexibility? Is there a downside to using oversized prisms if one intends to stick with HE? Aside from the relative pricing, of course.

[morkys]

Good question. I had a hard time deciding what size prisms to chose.