Build anamorphic with cylindrical lens

[roberto de la torre]

Hi,

 

This is a project that I´m working.

I´m looking to get shot wideangle with anamorphic adapters.

 

I´ve Hypergonar,Sankor...with excellent quality of image,but as many users know,these lens cannot be used with wide angles lens.And Cinemascope is for get WIDE,not just close ups.

 

My project start with the design of Soligor,Pana or Century adapters,that these can using almost with 30mm FF lens. So,the basic idea is get the quality glass of the Sankor (for example) and use on the Soligor design.

 

I got to know the measure and "potence" (I don´t know the term in english) of the each cylindrical lens of the Soligor adapter,just need get the same design build with achromatic glass (Achromatic doublet or whatever)

This one is x1.33 but I would like change to x2 (for use with R16mm film as well)

 

Appreciate if anyone has the manual of the design of the front atachment of the Lomo 22mm or whatever wide angle anamorphic.

 

The body of the lens must be another issue,but it´s not so important for now.

 

 

Sorry about my poor english.

[Tom McDonald]

I have emailed in the USA and around the world to try and find someone to do this. In the USA the two optical places I tried did not respond. In Euro a German Co. said they were not interested. I forget their names since it was a year or so ago and my email package does not search and find well.

 

I contacted the Leica motion picture lens people and they say they are not going for Anamorphic soon.

 

Usually this type adapter comes out of Asia where costs of R&D are lower. The USA is economically broke right now. Hope you find someone that will do it.

 

Apparently the Anamorphic part of the lens is an add on to a regular lens.

 

Maybe an optics forum, not photography forum, is a good place to look. Please post on this board if you find something out!

 

Check out this cool anamorphic footage of Kowa anamorphic on a Cannon Scopic 16mm:

http://www.youtube.com/watch?v=mMJ1680vExY

 

Check out this look thru the Kowa anamorphic in the attached picture.

[roberto de la torre]

heheh...same as you,Tom.

 

I´m glad to see someone interested for this issue as well.

I saw the Scoopic video a few times time ago.Looks nice but still looking tele-photo.

 

Understand your frustration with the optical places,I had the same experience and I gather we can´t require to build a anamorphic lens. They need the "power" from each lens. The axis,diopter,diameters,surface,centration,focal length,coating,cylindrical,spherical,plano-convex,biconcave,etc... When you have the "power" just contact with places like this one:

One for positive cylindrical:

http://www.altechna.com/product_details.php?id=58&product=Positive+Cylindrical+Lenses

And one for negative cylindrical:

http://www.altechna.com/product_details.php?id=59&product=Negative+Cylindrical+Lenses

 

Where to find out the power of the each lens? .. In places/shops for optical glasses,they have a machine that "read the power" in a few seconds.

I´ve the power of a 1,33x DV anamorphic adapter:

Front:

+10 Sp,-10 Cylindrical,180º

back:

-0,25 Sp,-11 Cy,90º

I´m not sure yet about these measures,I get it to read again,but it´s a good start.

 

Would be great get the power of the front attachment of wide angle anamorphic lens. These are very close each to the other and it´s x2. I can get the power of Sankor but it designed to keep the lens at a distance one another without being able to bring them to use with a wide angle,focus issues and less compression.

 

Another way to get wide angle is put a wide angle conversor in front of the anamorphic:

 

Just find a right power with achromatic glass.

 

I try with a cheap 0.5x wide angle conversor in front of the Sankor. It´s small,so vignette:

 

Cheers

 

R

[dan kessler]

I, too, have been down this road, having built a de-squeezer for a camera viewfinder.

 

Building a photographic-quality anamorphic adapter is much harder.

 

The first problem is that almost all off-the-shelf cylindrical lenses are simple plano-concave or plano-convex shapes.

While you can indeed put together an appropriate combination of focal lengths to obtain the desired amount of squeeze,

the system will suffer greatly from spherical, chromatic and other aberrations.

 

You need achromatic lenses to overcome these aberrations. I know of no company anywhere that manufactures achromatic

cylindrical lenses in a wide range of sizes and stocks them as standard items. Getting custom optics would be very

expensive and defeat the whole purpose of building it yourself.

 

The only other simple way to reduce aberrations is to stop the system way down, meaning that you could only use very

small apertures.

 

Cannibalizing existing adapters for their parts doesn't seem like a good solution, either.

[roberto de la torre]

Hi Dan,

 

Can tell me how you did the adapter for the viewfinder? which lens and where purchased?

 

About the problems said,you are right. I don´t care about the barrel distortion but CA is pain in my eyes,so I´m looking to avoid this if possible.

 

I removed the Hypergonar lenses from the body and it is compose with doublet lens each one,so it has four lens actually. I think there is the "achromatic trick",avoid the different wavelengths of light and focus the light to one point...thing not resolved with the "scam" $800 Panasonic AG-LA7200.

 

Well,my idea start in 3 fases:

1ª-get anamorphic x2 for wide angle lens. (I don´t care about the CA yet,just usable X2)

2º-Get out the CA (with the same design of the 1ª with doublet lens)

3º-focus sistem. (blend the focus with the distance of the two cylindrical lens...MUMP looks nice as well ...LOL)

[dan kessler]

Robert -

 

Your description of the hypergonar is exactly right. This was the original Cinemascope lens, by the way.

I think the limiting factor at wide angles is the barrel distortion. As far as I know, there's no way

around it unless you use a different lens design.

 

As for my viewfinder, I used the same principles, although my anamorphic lenses are not "in front," but

"in the middle." The objective lens of the viewfinder is a symmetrical design. I separated the two elements

so that the light rays between them would be parallel and put the anamorphic lenses in there. I reduced

the spherical aberration by making the negative cylindrical lens a double concave shape. Spherical and

chromatic aberration are further reduced by using a stop in the viewfinder system. It works quite well.

I bought all the lenses from a place called Surplus Shed for less than $50.

 

The main reason for building stuff is because we can't or won't spend thousands of dollars to buy the best

equipment. With off-the-shelf lenses, there are, of course, limitations. They work very well with

relatively narrow viewing angles at moderate to slow speeds. For a photographic lens, that means using

design principles that have been around for 150 years. Needless to say, though, wide, fast, well-corrected

photo lenses are far more demanding and anamorphics are more specialized. Can't build those quite so easily

with parts from Surplus Shed.

[roberto de la torre]

"in the middle" is the design of the Hawk,I think so. It would be a nice design as well: (Spherical-Diaphragm-anamorphic-spherical wide angle)

 

Anyway,barrel distirtion,as I said,is not a big problem for me,could be another "glamor" of the anamorphic´s artifact;oval bokeh,squint out focus,mump,flare...and barrel.

 

I know Surplus Shed,is where some guys purchase prismas for digital projection.

About your de-squeezer viewfinder, you purchased just a plano-convex and plano-concave lens with X measure for do anamorphic? I mean,you don´t needed specify the diopters,ratio,etc...? I´ve afraid to buy these and then have focus issues.

One problem I worry,is the combination of focal lengths to obtain the X2 squeeze,if I had to put in long distance each one to other to get x2,still as the same,can´t use wide angle. The best one should be 3cm lengths with a combinations of ratios with the two lens give squeeze X2.

 

That madness!! LOL

 

Still investigating!

 

Thanks,Dan.

[dan kessler]

The amount of squeeze is determined by the ratio of the focal lengths of the lenses.

 

For a 2x squeeze, the positive focal length is twice the negative focal length, with the negative lens

 

positioned at half the positive distance. The system is afocal, meaning that parallel rays enter and

 

leave. It's not an image forming system, but is designed to work with an image forming system.

 

Rays enter the negative element and exit the positive element. If you are familiar with graphical ray

 

tracing, you can draw this easily and understand how the system works.

 

 

I've been calling my set-up a de-squeezer, but it's really a squeezer. The image from the ground glass

 

has the 2x horizontal squeeze from the camera lens, and the viewfinder then applies a 2x vertical

 

squeeze to restore the image proportions. No matter, it's the same result.

 

 

I chose specific focal lengths to fit my design, but the actual values can vary.

 

Of course, if you buy lenses from a place like Surplus Shed, you are limited to what they have in stock.

 

If they don't have what you need, you're forced to go to a retail supplier, and you will naturally pay a lot more.

 

 

All of these cylindrical lenses are simple plano-concave or plano-convex, so aberrations are definitely

 

a concern.

 

 

I made my negative element into a double concave by cementing two plano-concaves flat-to-flat.

 

For this you start with two negative lenses that are twice the focal length you want, because the combined

 

focal length will be half. This improves the shape factor, helping to reduce the spherical aberration

 

of the overall system.

[roberto de la torre]

I see,

Many thanks for your help.

 

I know the squeeze or de-squeeze just depends on the degree of orientation. No matter for which was built.

 

I think I must learn more about the physic of the lenses.

 

About your system with two cemented plano-concaves,I also thought this idea would prevent the CA but,if I´m not wrong,need built with different kind of glass too.

Looking at my Hypergonar and other anamorphic that I have,they looks built like this:

 

By the way, on which cámera do you use the de-squeeze?

I´m thinking on get a Konvas,but get a Lomo kit could cost more than a two Konvas with spherical lenses,magazines....

Edited May 3, 2011 by roberto de la torre

[dan kessler]

My cemented lenses DO NOT correct CA. Achromatic lenses consist of two or more

positive and negative elements with different indices of refraction.

They can be cemented or air-spaced. Together they add up to a positive or a negative lens.

 

In my case, this is all for a home-built camera.