DIY anamorphic lens

[lesliew]

Prism Size

Hi Guys

I hope you can offer some advice on a choice of prisms.

I recently purchased the EPSON 8700UB projector which I am very happy with. The Epson is my 3rd projector but the first real home cinema quality PJ. I upgraded from a 6 year old DLP 4:3 native PJ with manual pull down screen, this dropped down in front of a wall mounted 42 TV".

Anyhow given the 8700's capabilities I thought I would do a total refit and am planning on installing a 120" 2.35:1 fixed screen and would love to build my very own anamorphic lens to cut my teeth on. I'm also planning on retro-fitting my 42" TV to a TV lift which will now come up in front of the fixed screen for casual viewing if everything goes to plan.

My media room is 16ft x 13ft, the PJ is ceiling mounted (9ft) and is as close to the rear wall as possible which gives me roughly 14.5ft projection distance.

I am ready to buy the prisms and start work but I am not sure of the sizes of prisms I should be looking at, big isn't always better (or is it). What size prisms do you guys recommend for my setup. I would prefer to buy a set that are AR coated, I do know that much.

TIA
Leslie

 

[AVWERK]

Mark t

Just purchased a JVC Pj this week. Is there any chance you will be selling just the glass for your circular/ adjustable version? I have a lathe myself and can do the hardware side.

Forgive me as I haven't read all the posts and I am a long time CRT man with too many of them now collecting dust..

Regards
David

 

[Mark Techer]

Hi David,

Send me an email using cavx01@hotmail.com and I will be able to sort you out.

Mark

 

[Mark Techer]

Here is the latest development of the MK5.

 

[Mark Techer]

Mark t

Just purchased a JVC Pj this week. Is there any chance you will be selling just the glass for your circular/ adjustable version? I have a lathe myself and can do the hardware side.

Forgive me as I haven't read all the posts and I am a long time CRT man with too many of them now collecting dust..

Regards
David

Hi David,

Which JVC did you buy? The X series will scale for 2D but not 3D. If you want to project 3D Scope, you need the MINI3D Radiance from Lumagen.

Mark

 

[AVWERK]

I purchased the rs10/hd350 because I could see the panel alignment before I bought (excellent) I'm familiar with the mini and what it can do, and will buying another pj after JVC solves the bulb/short arc/dim issues on the X series. 3D right now is of no interest and seems in beta mode with ghosting and other problems that I can wait for
I'm amazed what the baby lcos machine can do at this price

Regards
David

 

[Mark Techer]

They are awesome devices for sure.

 

[Mark Techer]

Anyway, in case anyone is still following this thread, here is the MK5 with its proper stand.

 

[billz260]

Mark, it seems during the year gap in activity on this thread you were quite busy on that MK5. Looks very professional How did you transition into the spherical lenses? It didn't seem like there was too much discussion on this thread about it despite a few attempts to get it going.

Do you have any screen shots of the MK3 vs MK5? Maybe some of the screen shots that you all began with, like the credits from cars or maybe something specific the MK3 was not handling that the 5 does very well?

Bill

 

[Mark Techer]

Mark, it seems during the year gap in activity on this thread you were quite busy on that MK5. Looks very professional How did you transition into the spherical lenses? It didn't seem like there was too much discussion on this thread about it despite a few attempts to get it going.

Do you have any screen shots of the MK3 vs MK5? Maybe some of the screen shots that you all began with, like the credits from cars or maybe something specific the MK3 was not handling that the 5 does very well?

Bill

Hi Bill,

In that time there has been a few products developed.

After the MK3 came the MK4. This was the first of the true cylindrical lenses.

Because the MK4 offered such a HUGE improvement over the MK3, I revisited it by developing the CAVX Corrector which when added to the MK3 improved the focus. The MK3 was then renamed the MK3+C.

Then came the MK5 when I wanted to cut the production costs of the MK4. The MK5 uses the same optics of the MK4, but focuses on the stand and its adjustments rather than just the optics. They were designed by a professional lens maker and can not be DIY'd. Same goes for both the prisms and correction lens in the MK3+C.

The ONLY way the MK5 could be DIY'd is to buy the glass (and I am the only person able to supply this at this time) and make your own case. Given how precise the case needs to be, this in itself is outside the realms of most DIY'ers anyway, and why the MK5 is now a finish professional product.

 

[billz260]

Do you have any direct comparison shots of the different MK versions showing how each improves over the last?

Are you making the MK3 +c? If not any hints as to the +C?

I don't even have a projector, just a room right now. My speakers came in this week, but the drivers and x-overs only, and it's a 7 speaker system, so that's quite a project in of itself I'm getting into the education step of my build and I want to absorb as much as I can.

I've read through this thread, and as well as some others. Any pointers to other sites or potential improvements to a simple (coated) 2 prism design is what I'm after.

Great read here, I guess everyone is happy with their 2 prism set ups after 2 years?

 

[Mark Techer]

Do you have any direct comparison shots of the different MK versions showing how each improves over the last?

I did a shoot out between the MK3, the MK3+C and the MK4 a while ago.

Are you making the MK3 +c? If not any hints as to the +C?

I did make 10 at the beginning of the year for a HiFi shop. The +C is a correction element for astigmatism correction. Each lens costs more to make that the prisms at the provide the anamorphic stretch.

I've read through this thread, and as well as some others. Any pointers to other sites or potential improvements to a simple (coated) 2 prism design is what I'm after.

The prisms used in the MK3 (MK3+C) were achromatic doublets. They were made for me by an optical company. To make them "affordable" I had to produce no less than 20 units at a time.

Great read here, I guess everyone is happy with their 2 prism set ups after 2 years?

No, they just had to realize and except that there is NO cheap way to get a better result because precision optics cost money. And just because one chooses the DIY path does not mean that the end result is even affordable.

 

[harthenry]

Looking to get into the game!

Hello everyone – Henry here, and I’m joining the party!
I too am in the process of building my video cave utilizing an anamorphic 2.35 setup. I am purchasing my screen from James at Jamestown utilizing the Seymour AT fabric. This is something new for Jamestown, for he did not sell AR fabric, you had to purchase the frame from Jamestown, and then the fabric from Seymour and then buckle them together after receipt. Now, you can get a turnkey 2.35 AT screen from Jamestown. – perhaps that is too much screen info for the DIY anamorphic site.
I now need a anamorphic lens, and was curious what wedge crystals Paul of “artbypaul” used for his setup – looked pretty nice in the pictures (back on page 174). Is a good place to procure these crystals “Precision Crystal”?
Thanks,
HH

 

[Mark Techer]

I am pretty sure he used the crystals from PC.

 

[Fishtank]

Kinda funny, I was getting more and more into the project, kinda excited for the end of the thread to see where everyone wound up...read from page 60-180 all day and it ends up killing my desire to create one in the last 10 pages!

The impression that I get is once HD projectors came out the prisms lost a lot of their "wow" factor compared to getting a nice big bright wide image out of a 4:3 projector.

Does anybody have any experience using the prisms on a modern 16:9 1080P projector? Not worth the effort? Image come out too soft on the left and right once people got used to HD content?

 

[Mark Techer]

Does anybody have any experience using the prisms on a modern 16:9 1080P projector? Not worth the effort? Image come out too soft on the left and right once people got used to HD content?

Many of us had a good run with 16:9 projectors. The issue is of course that there are limits to how good the image will be when using trophies - Chromatic Aberrations, Astigmatism, Grid Distortion, Ghosting, and even the Surface Finish of the actual glass all had a significant bearing on the outcome.

If you want perfection, then you will need to pay more than the $100 (average) paid for a pair of prisms. They are trophies after all and not optical spec.

 

[pbrown]

Bringing up a recently inactive topic and a relatively inactive user

With the help of this thread I have purchased 2 trophy lenses from evright and hope to get a start on my lens.

Now I know these trophies arent as good as other lens types but I'm trying to keep things cheap.

I have read I might be better going with a vertical compress setup if the throw is flexible. Are there any diagrams or details that show the lens orientation? I have searched a lot but can't find any. I'm sure I can work it out but just curious while I am waiting.

 

[Mark Techer]

Are there any diagrams or details that show the lens orientation? I have searched a lot but can't find any. I'm sure I can work it out but just curious while I am waiting.

Here you go

I hope this helps. The arrows signify the beam direction from the projector. So if you are familiar with the HE (Horizontal Expansion) design, you then rotate the array 180 degrees which now forms a HC (Horizontal Compression) lens, then stand it upright to make it a VC (Vertical Compression) lens.

You will need a longer TR (Throw Ratio) to make this work and to allow the larger image but you should get significantly better results.

Good luck with that.

 

[Mark Techer]

I can't edit my post above, so your throw ratio is the same, the actual throw distance is longer for a VC.

 

[pbrown]

Thanks Mark. I'm limited in width for the picture so the VC approach works well for me. It just reduces the height which is fairly flexible with my black magic (Aussie version) painted wall.

I have already played with resolutions and made sure my project will accept the extra wide resolution and still display it full screen in a different aspect ratio rather than letter box on the DESKTOP. Not sure if that makes sense but to sum it up, I can use the full resolution of the projector and have it look stretched on the desktop (and this every program) then use the lenses to bring it back into the extra wide aspect ratio.

I got the trophies and had a quick play with them. Problem is my projector is mounted to the ceiling so its not that easy. I did pull it down and play around at roughly the same throw and got something. It was much easier to test for stretching horizontally due to the prisms being easily rotated on the table. But the VC approach is difficult to stand them up at angles so this was a bit more difficult.

I gave up because I preferred just loosing the resolution to the black bars because the HS approach had too much pin cushioning and chromatic aberration with my limited playing around.

But you have got me tempted again knowing that the VC will yield noticeably better results. The good news is my screen doesn't have borders so pin cushioning isn't as evident as there is no straight edge near by except for maybe the sides (approx 100mm away from edge). But at the same time it doesn't have the edging to hide the edges of the screen..

Thanks for your reply as you have got my temptation going again. It was sort of a waste buying the prisms and not using them until I get the bug to buy a better lens. I feel I might be happier using the VC approach over loosing 1/3rd of my resolution. But the HS approach wasn't so tempting on the rough play around I had.