Anamorphic Lens Design

Discussion in 'Camera Building, Repairs & Modification' started by Mustafa Umut Sarac, Apr 29, 2011.

  1. Mustafa Umut Sarac

    Mustafa Umut Sarac Member

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    Can I build a working , focusing lens with one horizontal cylinderical lens and one vertical cylinderical lens ? I want to cut a big block of transparent cast plastic with water jet. I am thinking an inverted galile design with only non spherical but cylinderical lenses . And I am thinking to build spacers around these two lens couples with not metal but directly non cut plastic.

    I had been posted a similar thread couple of years ago but it went off road.

    Thank you ,

    Umut
     
  2. johnielvis

    johnielvis Member

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    seems to me no----unless different cylinders---one will be behind the other---if same focus length, then both will be out of focus by the difference in where they are located on the axis, right?....so one plane in focus at z=fl and one plane in focus at z=fl+radius.....either way...one plane out of focus whehere other plane in focus
     
  3. Worker 11811

    Worker 11811 Member

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    I'm not sure I understand what you want to do but what I know about anamorphics is this: You have a prime lens and the anamorphic prism attached to the front of it. It can be arranged as an integral system, all inside one lens body, or you can have the anamorphic and prime lenses as two separate devices which couple together. This is the most common arrangement in my experience.

    The anamorphic attachment has its own focusing gear which brings the nodal point of the prism in line with the nodal point of the prime lens. If you don't do this, you'll have vertical lines in focus but horizontal lines out of focus or vice versa. In cine projectors, once the anamorphic is focused to the prime it is locked down and not touched again. Focusing the image means simply racking the entire lens assembly forward and backward using a knob attached to a rack and pinion or a worm gear.

    For cine cameras (versus projectors) they usually use some kind of integral design but they still have two focus adjustments. Do a search for "Panavision" lens and you'll be able to find some photos of anamorphic cine camera lenses. Some of those things are monstrous size! Upwards of 5 kg.

    Since you seem to know more about lens design than I do, take this with a grain of salt. I understand this from a practical use standpoint in daily work. My understanding is likely to be different than yours.

    However, I have a question. If you're designing an anamorphic lens for a still camera, wouldn't you have to design a complementary lens for the enlarger too?
     
  4. Mustafa Umut Sarac

    Mustafa Umut Sarac Member

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    John ,

    Randy ,

    Thank you for your answers.

    Let me start from John , Yes , I am thinking to use two cylinder lens one behind of another. One of them will be horizontal , the other one will be vertical. What is the way to focus two planes together ? I saw a panasonic design and third element was a spherical but I dont want it because it is not available to me to water jet cut a spherical lens or buying , ordering a special design.

    Randy , may be You are right , best way to design a attachment with a prime. There are tons of cheap lenses available and it can be thinked by this way and I survive from messing with a third spherical element design.

    Thank you very much ,

    Umut