Building DIY cylindrical lens? - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #1 of 44 Old 09-24-2011, 07:01 AM - Thread Starter
Senior Member
 
rukus29's Avatar
 
Join Date: Jan 2008
Posts: 202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
I'll go the manufacture root but I'm curious if anyone has built one? I'm curious to read up on exactly how they work.
rukus29 is offline  
Sponsored Links
Advertisement
 
post #2 of 44 Old 09-25-2011, 05:16 PM
AVS Special Member
 
CAVX's Avatar
 
Join Date: Aug 2005
Location: Brisbane, Australia
Posts: 8,385
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked: 44
Quote:
Originally Posted by rukus29 View Post

I'll go the manufacture root but I'm curious if anyone has built one? I'm curious to read up on exactly how they work.

When you say "built" are you asking if someone was able to make an anamorphic lens from actual lenses (the answer being yes) or if someone made their own lenses similar to the way people were making the prisms years ago (the answer being no)?

There is too much precision required here for any DIYer to do this.

You can buy your own lenses and make your own case, but know now, the glass is not cheap. Your still looking at a few grand for a good set of corrected cylindrical optics

Mark Techer

I love my Constant Image Height system!
CAVX is offline  
post #3 of 44 Old 09-25-2011, 06:09 PM - Thread Starter
Senior Member
 
rukus29's Avatar
 
Join Date: Jan 2008
Posts: 202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by CAVX View Post

When you say "built" are you asking if someone was able to make an anamorphic lens from actual lenses (the answer being yes) or if someone made their own lenses similar to the way people were making the prisms years ago (the answer being no)?

There is too much precision required here for any DIYer to do this.

You can buy your own lenses and make your own case, but know now, the glass is not cheap. Your still looking at a few grand for a good set of corrected cylindrical optics

yup - i had meant making it by buying the glass and building a frame DIY-style. was more about curiosity than actually building it as i doubt i have the tools to build it as precisely as it needs to be.
rukus29 is offline  
post #4 of 44 Old 09-25-2011, 06:20 PM
AVS Special Member
 
CAVX's Avatar
 
Join Date: Aug 2005
Location: Brisbane, Australia
Posts: 8,385
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked: 44
Quote:
Originally Posted by rukus29 View Post

yup - i had meant making it by buying the glass and building a frame DIY-style. was more about curiosity than actually building it as i doubt i have the tools to build it as precisely as it needs to be.

As long as the case is made to hold both lenses vertically aligned and parallel to each other, you should be able to make this work.

Mark Techer

I love my Constant Image Height system!
CAVX is offline  
post #5 of 44 Old 09-25-2011, 08:09 PM - Thread Starter
Senior Member
 
rukus29's Avatar
 
Join Date: Jan 2008
Posts: 202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by CAVX View Post

As long as the case is made to hold both lenses vertically aligned and parallel to each other, you should be able to make this work.

Thanks again - is there anywhere good to read up these designs and how to determine how far apart to space the lenses, what types of lenses work best, etc?
rukus29 is offline  
post #6 of 44 Old 10-13-2011, 05:22 PM
AVS Special Member
 
kgveteran's Avatar
 
Join Date: Apr 2004
Location: Rochester NY
Posts: 5,722
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 34 Post(s)
Liked: 39
Where would these raw lenses be found
kgveteran is offline  
post #7 of 44 Old 10-13-2011, 05:58 PM
AVS Special Member
 
CAVX's Avatar
 
Join Date: Aug 2005
Location: Brisbane, Australia
Posts: 8,385
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked: 44
Quote:
Originally Posted by kgveteran View Post

Where would these raw lenses be found

You don't just "find" these lenses, they have to be made and they are not cheap.

Mark Techer

I love my Constant Image Height system!
CAVX is offline  
post #8 of 44 Old 10-14-2011, 03:45 PM - Thread Starter
Senior Member
 
rukus29's Avatar
 
Join Date: Jan 2008
Posts: 202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Mark, do you have any handy links to the theory of designing these things, ie how to choose the lenses, spacing, curvature, etc to get the proper expansion while keeping geometric and any other distortion to a minimum?

Thanks,
Rukus
rukus29 is offline  
post #9 of 44 Old 10-26-2011, 04:26 PM
AVS Special Member
 
kgveteran's Avatar
 
Join Date: Apr 2004
Location: Rochester NY
Posts: 5,722
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 34 Post(s)
Liked: 39
Quote:
Originally Posted by CAVX View Post

You don't just "find" these lenses, they have to be made and they are not cheap.

Hmmm, to much told here and the cats out of the bag
kgveteran is offline  
post #10 of 44 Old 10-26-2011, 05:26 PM
AVS Special Member
 
CAVX's Avatar
 
Join Date: Aug 2005
Location: Brisbane, Australia
Posts: 8,385
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked: 44
Quote:
Originally Posted by kgveteran View Post

Hmmm, to much told here and the cats out of the bag


If you want to do a DIY version that actually works, you will need to spend the $$$$. Yes 4 figures

Prisms are quite forgiving. Cylindrical lenses are not. They must be aligned to less than 100th of a degree vertically if you want the sub-pixel clarity owners of these high end lenses claim they can get.

Mark Techer

I love my Constant Image Height system!
CAVX is offline  
post #11 of 44 Old 11-02-2011, 05:10 PM
AVS Special Member
 
coolrda's Avatar
 
Join Date: Nov 2002
Location: Bakersfield, CA
Posts: 1,021
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 12
Quote:
Originally Posted by CAVX View Post


If you want to do a DIY version that actually works, you will need to spend the $$$$. Yes 4 figures

Prisms are quite forgiving. Cylindrical lenses are not. They must be aligned to less than 100th of a degree vertically if you want the sub-pixel clarity owners of these high end lenses claim they can get.

Exactly, I had a DIYer by the name of Ignacio Sigfried Charles Olivier, the third, make mine.
coolrda is offline  
post #12 of 44 Old 11-02-2011, 05:28 PM
AVS Special Member
 
CAVX's Avatar
 
Join Date: Aug 2005
Location: Brisbane, Australia
Posts: 8,385
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked: 44
Quote:
Originally Posted by coolrda View Post

Exactly, I had a DIYer by the name of Ignacio Sigfried Charles Olivier, the third, make mine.

Cool. PM me his details

Mark Techer

I love my Constant Image Height system!
CAVX is offline  
post #13 of 44 Old 11-10-2011, 01:48 PM
AVS Special Member
 
coolrda's Avatar
 
Join Date: Nov 2002
Location: Bakersfield, CA
Posts: 1,021
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 12
Quote:
Originally Posted by coolrda View Post

exactly, i had a diyer by the name of ignacio sigfried charles olivier, the third, make mine.

IOW, Isco 3.
coolrda is offline  
post #14 of 44 Old 11-10-2011, 11:59 PM
AVS Special Member
 
CAVX's Avatar
 
Join Date: Aug 2005
Location: Brisbane, Australia
Posts: 8,385
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked: 44
Quote:
Originally Posted by coolrda View Post

IOW, Isco 3.

Yes and why I was

Mark Techer

I love my Constant Image Height system!
CAVX is offline  
post #15 of 44 Old 11-11-2011, 12:52 AM
AVS Special Member
 
coolrda's Avatar
 
Join Date: Nov 2002
Location: Bakersfield, CA
Posts: 1,021
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 12
Quote:
Originally Posted by CAVX View Post

Yes and why I was

I got a couple PM's asking, so I posting that here. As I told those who pm'd it was an inside joke for CAVX. Knew he'd get it.
coolrda is offline  
post #16 of 44 Old 11-11-2011, 06:10 AM
Scott Horton, techht.com
 
GetGray's Avatar
 
Join Date: Aug 2004
Location: Mid-South USA
Posts: 5,456
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
Liked: 52
I thought it was obvious . Sorry if they are reading this but if you got PM's asking where to get Ignacio's lens, that's funny
GetGray is offline  
post #17 of 44 Old 11-12-2011, 04:07 PM
AVS Special Member
 
CAVX's Avatar
 
Join Date: Aug 2005
Location: Brisbane, Australia
Posts: 8,385
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked: 44
Quote:
Originally Posted by GetGray View Post

I thought it was obvious . Sorry if they are reading this but if you got PM's asking where to get Ignacio's lens, that's funny

They won't except the fact that these lenses cost what they do for a reason and so hang on in quiet desperation for their dream $20 solution. It's NOT going to happen. There is a HUGE difference between true lenses and trophies, yet for some reason, they won't accept that.

Mark Techer

I love my Constant Image Height system!
CAVX is offline  
post #18 of 44 Old 11-14-2011, 05:09 AM
AVS Special Member
 
kgveteran's Avatar
 
Join Date: Apr 2004
Location: Rochester NY
Posts: 5,722
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 34 Post(s)
Liked: 39
Oh well, maybe some rich,rich lens grinder will donate some for us poe folks.......
kgveteran is offline  
post #19 of 44 Old 11-14-2011, 03:06 PM
AVS Special Member
 
CAVX's Avatar
 
Join Date: Aug 2005
Location: Brisbane, Australia
Posts: 8,385
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked: 44
Quote:
Originally Posted by kgveteran View Post

Oh well, maybe some rich,rich lens grinder will donate some for us poe folks.......



These lenses need to be within less than 1/60th of a degree to perfect vertical alignment with less 100th of a degree preferred. This is not really DIY stuff, though it can be done in DIY. Even though I assemble my own lenses, I have had to spend more on set up gear than some people want to spend on their entire system set ups. This is includes but is not limited to a cleaning station and gear for laser alignment.

Each lens can take several hours to get aligned and tested. This is not a case of lets slap it all in a MDF box and whack it in front of the projector. This needs precision and why all my case parts are machined.

Mark Techer

I love my Constant Image Height system!
CAVX is offline  
post #20 of 44 Old 11-14-2011, 07:07 PM - Thread Starter
Senior Member
 
rukus29's Avatar
 
Join Date: Jan 2008
Posts: 202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by CAVX View Post



These lenses need to be within less than 1/60th of a degree to perfect vertical alignment with less 100th of a degree preferred. This is not really DIY stuff, though it can be done in DIY. Even though I assemble my own lenses, I have had to spend more on set up gear than some people want to spend on their entire system set ups. This is includes but is not limited to a cleaning station and gear for laser alignment.

Each lens can take several hours to get aligned and tested. This is not a case of lets slap it all in a MDF box and whack it in front of the projector. This needs precision and why all my case parts are machined.

i personally was more interested in the theory and design, as i plan to pick up a quality lens at some point in the next few months. that, and i dont have the space to assemble the setup needed to get the precision required (as you mentioned you have).
I'm just a tinkerer by nature and would just like to read about the theory and methods used to build them.
rukus29 is offline  
post #21 of 44 Old 11-23-2011, 10:36 AM
Member
 
Doc Pete's Avatar
 
Join Date: Jun 2010
Location: Atlanta, GA
Posts: 116
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Rukus29,
I too have thought about trying to make a cylinder lens. Right now I'm finishing the building of my theater and then if i don't get into building guitar amps, i was gonna try to build a cylinder scope lens. I'm an optometrist so I can easily get high grade glass cylinder lenses, with anti-reflection, for very little cost.
No one on here will give you any info on how to build one, or more importantly, the optical settings due to the fact that they spent a bunch of time figuring it out and are now selling the products and don't want to lose out to DIY folk making their own. I personally think the cylinder lenses are marked up A LOT, but then again that's the market price until someone comes out with a cheaper version. But i could be wrong.
If building your own lens was this costly ("$$$$")and difficult to build your own cylinder lens then they would easily give that info out because they know you would fail and/or give up due to start up costs. So I'm thinking its not as bad as it sounds. 1/100ths of a degree would only be a measurement important to NASA definitely not to the system. Nobody can correct it that close, in fact that amount of detail is insignificant for a optical lens for a HT. IF that were true then the guy that had the -6.00 amount of astigmatism in his glasses would not be able to see anything with glasses as all glasses are corrected on intervals of 5 degrees, no where near 1/100th of a degree. If you make a system corrected to that detail and that is important to you then you need to get your eye prescription updated, for changes, every month!

It generally takes 4 cylinder lenses (cylinder lenses are the type used to correct peoples vision when they have astigmatism: ie eye shaped like an american football) The more lenses used, the more optical clarity that can be corrected for. But I haven't actually worked it out yet but the materials aren't that expensive nor do you need to work for NASA.

My 2 cents, thats all.
Doc Pete is offline  
post #22 of 44 Old 11-23-2011, 02:04 PM - Thread Starter
Senior Member
 
rukus29's Avatar
 
Join Date: Jan 2008
Posts: 202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Doc Pete View Post

Rukus29,
I too have thought about trying to make a cylinder lens. Right now I'm finishing the building of my theater and then if i don't get into building guitar amps, i was gonna try to build a cylinder scope lens. I'm an optometrist so I can easily get high grade glass cylinder lenses, with anti-reflection, for very little cost.
No one on here will give you any info on how to build one, or more importantly, the optical settings due to the fact that they spent a bunch of time figuring it out and are now selling the products and don't want to lose out to DIY folk making their own. I personally think the cylinder lenses are marked up A LOT, but then again that's the market price until someone comes out with a cheaper version. But i could be wrong.
If building your own lens was this costly ("$$$$")and difficult to build your own cylinder lens then they would easily give that info out because they know you would fail and/or give up due to start up costs. So I'm thinking its not as bad as it sounds. 1/100ths of a degree would only be a measurement important to NASA definitely not to the system. Nobody can correct it that close, in fact that amount of detail is insignificant for a optical lens for a HT. IF that were true then the guy that had the -6.00 amount of astigmatism in his glasses would not be able to see anything with glasses as all glasses are corrected on intervals of 5 degrees, no where near 1/100th of a degree. If you make a system corrected to that detail and that is important to you then you need to get your eye prescription updated, for changes, every month!

It generally takes 4 cylinder lenses (cylinder lenses are the type used to correct peoples vision when they have astigmatism: ie eye shaped like an american football) The more lenses used, the more optical clarity that can be corrected for. But I haven't actually worked it out yet but the materials aren't that expensive nor do you need to work for NASA.

My 2 cents, thats all.

i am wondering how precise the vertical alignment needs to be. i suppose it can be tested but i would imagine any non parallel alignment would result in some splitting of the colors when passing through the glass.

as for the cost, i imagine it is the size of the lenses needed that causes the increase in $$. i think you need a significantly bigger piece of glass to work around a PJ lens than a human eye. but perhaps you tell me the price increase is not that much.

That said, am happy to take this conversation to PMs to continue it. I basically would need access to the properties of the glass you have access to (ie refraction index, size, etc) and can then probably come up with some rough designs, angles, etc.

Don't think I would try to build something unless i was 100% sure the alignment of the multiple lenses wasn't as critical as i think it may be.
rukus29 is offline  
post #23 of 44 Old 11-23-2011, 03:06 PM
AVS Special Member
 
CAVX's Avatar
 
Join Date: Aug 2005
Location: Brisbane, Australia
Posts: 8,385
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked: 44
Quote:
Originally Posted by Doc Pete View Post

Rukus29,
I too have thought about trying to make a cylinder lens. Right now I'm finishing the building of my theater and then if i don't get into building guitar amps, i was gonna try to build a cylinder scope lens. I'm an optometrist so I can easily get high grade glass cylinder lenses, with anti-reflection, for very little cost.

How large? What about correction?

Quote:


No one on here will give you any info on how to build one, or more importantly, the optical settings due to the fact that they spent a bunch of time figuring it out and are now selling the products and don't want to lose out to DIY folk making their own.

Good luck to any DIY'er that want to make their own. I just don't think it is possible to get the level I have now from DIY and since 2008, I spent well over $80K to get it this far. But hey, if you think you can do it for less, go for it

Quote:


I personally think the cylinder lenses are marked up A LOT, but then again that's the market price until someone comes out with a cheaper version. But i could be wrong.



Plastic versions have been done and rejected. Glass/plastic versions were also trialed and rejected. In the end, only an all glass optical system works at the level we expect.

Quote:


If building your own lens was this costly ("$$$$")and difficult to build your own cylinder lens then they would easily give that info out because they know you would fail and/or give up due to start up costs. So I'm thinking its not as bad as it sounds. 1/100ths of a degree would only be a measurement important to NASA definitely not to the system.

Clearly (yes pun intended) you've not assembled one then. In my case, the radius of the glass is what would be called multi-aspheric where the radii are actually multiple. The machine that cuts this glass also polishes the glass. It is time consuming and expensive, hence the $$$$.

Quote:


Nobody can correct it that close, in fact that amount of detail is insignificant for a optical lens for a HT. IF that were true then the guy that had the -6.00 amount of astigmatism in his glasses would not be able to see anything with glasses as all glasses are corrected on intervals of 5 degrees, no where near 1/100th of a degree. If you make a system corrected to that detail and that is important to you then you need to get your eye prescription updated, for changes, every month!

I won't challenge your claim on corrective eye ware because this is not corrective eye.

Quote:


It generally takes 4 cylinder lenses (cylinder lenses are the type used to correct peoples vision when they have astigmatism: ie eye shaped like an american football) The more lenses used, the more optical clarity that can be corrected for. But I haven't actually worked it out yet but the materials aren't that expensive nor do you need to work for NASA.

My 2 cents, thats all.

And your entitled to it.

Mark Techer

I love my Constant Image Height system!
CAVX is offline  
post #24 of 44 Old 11-23-2011, 03:12 PM
AVS Special Member
 
CAVX's Avatar
 
Join Date: Aug 2005
Location: Brisbane, Australia
Posts: 8,385
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked: 44
Quote:
Originally Posted by rukus29 View Post

i am wondering how precise the vertical alignment needs to be. i suppose it can be tested but i would imagine any non parallel alignment would result in some splitting of the colors when passing through the glass.

I do believe I stated 100% vertically aligned. This is nothing to do with 'splitting of colours', the CA correction in the lenses themselves handles that. I'm talking about getting the image to focus in both H and V plains at the same time. If you think you can just eye ball these in, think again.

Quote:


as for the cost, i imagine it is the size of the lenses needed that causes the increase in $$. i think you need a significantly bigger piece of glass to work around a PJ lens than a human eye. but perhaps you tell me the price increase is not that much.

Then go into manufacturing and show me how it can be done for less because I would love to be able to supply these lenses for less and not go broke in the process.

Mark Techer

I love my Constant Image Height system!
CAVX is offline  
post #25 of 44 Old 11-23-2011, 03:37 PM
Scott Horton, techht.com
 
GetGray's Avatar
 
Join Date: Aug 2004
Location: Mid-South USA
Posts: 5,456
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
Liked: 52
Not to be discouraging but...

Schneider tried for years to release a *medium* format lens to compete with the "large" format Isco IIIL. They were unable to. Now this is the largest optics company in the world, with their specialty being high end photographic lenses and cinema lenses. They are building lenses for video, not NASA. If you ever saw a Cinemascope film, you watched it projected through a Schneider or an Isco lens. Schneider had their very small original Cinedigitar lens which was reported by their competitors to not have the same image quality as the larger lenses. But after years of saying they were working on one, none ever appeared; Only prototypes that they said were not suitable for public release. And they never were released.

So they bought Isco. Isco specializes in the large optics and is one of the only places that knows how to, or at least can, do it correctly. Isco is now the anamorphic division of Schneider, making all their large format A-lenses.

Now if Schneider worldwide couldn't do it (right), I'm not going to hold my breath many DIYers can do it right either.

To do it and produce a lens that does not cause ghosting, or has abysimal MTF, much less proper geometric expansion, vertical and horizontal focus, etc. etc. isn't as trivial as you made it sound.

Now, once you get into production, just to get your sample prototype piece made to see if your optical modeling was correct is big $$.

I'd love to see a cheap lens done well. Haven't yet. Becasue I know a lot about what it takes for the glass (we haven't even touched mechaincs yet), I won't hold my breath.

Then again, if you lower your standards and expectations enough on what a cheap lens does (or does not do) to your images, you might make a cheaper one. How much cheaper after all that R&D and pain, doubt enough to break even. You may be happier with a higher end prisim.

Or you found some secret the optical engineers at Schneider couldn't figure out.
GetGray is offline  
post #26 of 44 Old 11-23-2011, 06:16 PM - Thread Starter
Senior Member
 
rukus29's Avatar
 
Join Date: Jan 2008
Posts: 202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by CAVX View Post

I do believe I stated 100% vertically aligned. This is nothing to do with 'splitting of colours', the CA correction in the lenses themselves handles that. I'm talking about getting the image to focus in both H and V plains at the same time. If you think you can just eye ball these in, think again.

Then go into manufacturing and show me how it can be done for less because I would love to be able to supply these lenses for less and not go broke in the process.

I was agreeing with your previous posts that a) im pretty sure alignment needs to be perfect and b) making high quality optical lenses of that size is probably quite expensive (i have not looked into this).... that all said, if someone convinces me otherwise i am more than happy to actually give it a go at building. for now im just interested in the theory.
rukus29 is offline  
post #27 of 44 Old 11-23-2011, 07:54 PM
AVS Special Member
 
CAVX's Avatar
 
Join Date: Aug 2005
Location: Brisbane, Australia
Posts: 8,385
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked: 44
Quote:
Originally Posted by rukus29 View Post

for now im just interested in the theory.

The theory was in that link I sent you in PM. The rest is practical and where the expense kicks into high gear.

What irks me is the comments by people with no idea at all making claims that we can just "find" these lenses and make these for way less than a commercial product. We did indeed "find" (thanks to Steve S) trophies that could work as the prisms in a DIY prism based lens. This is not prisms. There are no angles here except 0.0 degrees and being able to hold the precisely ground lenses 100% parallel horizontally and vertically to each other, then be able to move one in or out and still maintain that alignment.

Mark Techer

I love my Constant Image Height system!
CAVX is offline  
post #28 of 44 Old 02-24-2012, 08:36 AM
Newbie
 
riskpeep's Avatar
 
Join Date: Sep 2007
Posts: 13
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I'd love to understand more about the theory of this. I fully understand that its complicated and perhaps out of the realm of most DIY, but right now I'm not sure I care. I'm an engineer and I love to tinker, so being able to understand the theory of how to design such a lens would be extremely interesting to me.

I too have had a belief that you could go very far with eyeglass lens blanks. I'd really like to explore that possibility, but until I know where to start, I can just look at pages of lens blanks and not know which ones make sense.

What I'm trying to figure out is which lenses. How far apart, etc. I know they need to be all cylindrical, and I'm certain that the alignment tolerances are tight. But even if I had the all the equipment in the world, I'd need some theory to know what lens to grind and where to put it to even begin the alignment process. Its that theory that I'd love to figure out.

Is anyone here able to help with that?

R
riskpeep is offline  
post #29 of 44 Old 02-27-2012, 05:26 AM
AVS Special Member
 
CAVX's Avatar
 
Join Date: Aug 2005
Location: Brisbane, Australia
Posts: 8,385
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Liked: 44
Quote:
Originally Posted by riskpeep View Post

Is anyone here able to help with that?

Yes they must be cylindrical and yes the alignment is paramount.



LL

Mark Techer

I love my Constant Image Height system!
CAVX is offline  
post #30 of 44 Old 02-27-2012, 08:08 AM
Newbie
 
riskpeep's Avatar
 
Join Date: Sep 2007
Posts: 13
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Mark,

Thank you for your reply, this is helpful. Is the distance between the lenses particularly relevant, or just the alignment between them?

I've been doing some additional research on this and what I know so far is that eyeglass blanks are measured in diopters. At the risk of being pedantic, a diopter (http://en.wikipedia.org/wiki/Dioptre) is a measure of the optical power of a lens and is the reciprocal of the focal length, so a 3 diopter lens would have a focal length of 1/3 of a meter. Lenses can be found in 0.25 increments of diopters.

The interesting bit is that for an eyeglass prescription (and thus for readily available lenses), you have a spherical measure (which is a general magnification), and a cylindrical measure. We only care about cylindrical power, so the appropriate lenses with the correct cylinder rating is what we'd need.

My understanding is that for an Anamorphic lens, we want a 1.33x expansion lens which should be achievable with two lenses having the right ratio between their Diopter ratings. I found one person on the web who'd had success with experimenting at an anamorphic stretch using a -6 cylinder lens paired with a +4.5 cylinder lens, but he was using opthalmic test lenses with a diameter of ~1" and thus couldn't pass the whole beam of his projector.

You should be able to use any two lenses with the correct ratio between them, so if I have this right, you could use a -6 & a +4.5 cylinder lens, or a -3 and a +2.25 lens.

If we can find someone with access to eyeglass lens blanks and a projector, it would seem a simple test to put two lenses in front of a projector to see if we're approaching this problem right. Obviously you'd need to get the orientation right (being cylindrical lenses, they do have a directionality, and between the two lenses the directionality would need to be exactly lined up.
riskpeep is offline  
Reply DIY Constant Height

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off