AVS Forum banner

Status
Not open for further replies.
1 - 13 of 13 Posts

·
Registered
Joined
·
1,622 Posts
Discussion Starter · #1 ·
Would an anamorphic lens for camcorders work for projectors? Or will the picture not come out right when the light goes the other way through the lens?

http://www.zgc.com/html/anamorphic_attachment.html


The lens in the link above has a threaded flange of 52mm, I could probably screw my HOYA HMC FL-D filter onto it as well. :) Not if the thread are inside threads though, which I suspect they are.


Is it possible to construct a simple (low quality) anamorphic lens with readily available parts? Possibly a very stupid question. :) I'm trying to find out how the different anamorphic lenses are constructed, but haven't found any drawings or pictures to show how.



Tor Arne
 

·
Registered
Joined
·
375 Posts
Ok, I'll bite.


For starters, anamorphic lenses built for cameras have high throughput losses. Usually 50% or more of the light is lost.


For a low cost anamorphic lens "science project" try this: obtain two solid-but-flexible acrylic-substrate aluminumized first-surface mirrors. Bend the mirrors slightly and arrange them periscope fashion in front of the projector. Obviously the second mirror needs to be larger than the one nearest the projector lens. By varying the amount of bend (and the rate of bend from center-to-edges) you can get a variable anamorphic lens with only 10 to 15% light loss.


Actually only one of the mirrors need to be curved but two makes it more fun :)


Something to play around with.


Thumper
 

·
Registered
Joined
·
6,227 Posts
There was a good page in german about DIY'ing a anamorphic lens using the offset prism function like a Pannie... People have also had luck looking for clean Panatars (I believe the 'super' rather than 'ultra' was best to try for larger aperture entrance lens) which are variable compression.... The image abberations may be greater with variable squeeze but think of the possibility of an X10 control motor on this... Push button sqeeze from 4:3 to 2.35:1 would be the absolute holy grail of anamorphic lenses... Hook up the X10 to HTPC controller and interface it with a YxY like window control application and you could have a single controller that optically compresses at the same rate as it controls the scaler to stretch....


As you may be able to tell I have insomnia and a wandering imgination :D !!
 

·
Registered
Joined
·
4,720 Posts
Quote:
Originally posted by Thumper


For a low cost anamorphic lens "science project" try this: obtain two solid-but-flexible acrylic-substrate aluminumized first-surface mirrors. Bend the mirrors slightly and arrange them periscope fashion in front of the projector.
Thumper,


Yes - such a "periscope" system will work - and one of the early designs for the Panamorph was such a periscope system.


Shawn Kelly later went with the prism design that defines the current Panamorph lens.


Dr. Gregory Greenman

Physicist
 

·
Premium Member
Joined
·
24,813 Posts
A guy at work who knows optics told me the cylindrical mirror implementation will suffer from astigamtism. Otherwise it would seem preferable to prisms because of simplicity and lack of chroamtic abberration.


Thanks
 

·
Registered
Joined
·
1,622 Posts
Discussion Starter · #6 ·
Hmm, I think I'll wait for the vertical squeeze Prismasonic instead. :) It should be available this fall. My projector has a short-throw lens.


I would really like to try an anamorphic lens.



Tor Arne.
 

·
Registered
Joined
·
6,227 Posts
Current Pannie is a vertical squeeze lens !!! I am guessing you are after a horizontal expansion lens like the ISCO based on a prism design ??
 

·
Registered
Joined
·
1,622 Posts
Discussion Starter · #8 ·
No, vertical squeeze. The Pannie is WAY too expensive for me. The Prismasonic is very cheap and sholdn't cost more than $600.



Tor Arne
 

·
Registered
Joined
·
5,574 Posts
thumper,


Where might I obtain the mirrors for your "science fair" anamorphic lens.


I'm always up to trying something if it's cheap! :)



Thanks!


Bob
 

·
Registered
Joined
·
375 Posts
The astigamtism mentioned by Noah Katz above is a problem for constant curve (linear) cylindrical mirrors.


The beauty of the flexible mirrors is the ability to change the rate of curve from one side to the other and therefore effect astigmatism corrections, even perform keystone and barrelling corrections :)


BTW, for reference: in the "periscope" model I wrote of earlier one or both mirrors are flexed in a convex shape with the "bows" facing each other.


Morbius, if I remember correctly, the complexity (read $$$) of F.S. mirrored glass cylinders was one of the major factors in Shawn K. moving to L.F. prizims.


Just for S & Gs I built one of these "periscopes" sometime back and it actually does work quite well. The only real difficulty is a backside mechanical means of adjusting and holding the proper mirror curve(s). With such mirrors now in the 3 to 5% each loss range it would be possible to build a device with 10 to 15% total loss (including input/output port glass)


So there you have it... A means of creating a low loss, variable horizontal expansion rate anamorphic lens with keystone/barrel correction :p


Thump
 
1 - 13 of 13 Posts
Status
Not open for further replies.
Top