"Enlarging" with a fresnel sheet magnifier?

Discussion in 'Enlarging' started by mabman, Jul 24, 2011.

  1. mabman

    mabman Member

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    Just curious, has anyone tried creating something of an "enlargement" using a fresnel sheet magnifier (such as one seen here)?

    I envision something like a contact print, but with the sheet magnifier between the negative and the photo paper. If so, what does the end result look like? I would imagine there would be some distortions, etc. Perhaps I'm not searching correctly, but I can't find any examples of this directly.

    It's an idle question, but I've seen these sheet magnifiers in stores a few times, and often wondered what the effect would be as an "enlarging" device.
     
  2. Mustafa Umut Sarac

    Mustafa Umut Sarac Member

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    Put a print under this plastic fresnel magnifier ,whatever you see, will be whatever you get from contact print. I think fresnel magnifier plastic will focus the source light in to the paper and you will see dark and light circular rings.

    Umut
     
  3. Gerald C Koch

    Gerald C Koch Member

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    Fresnel lenses are fine for concentrating light but cannot be used for imaging. The circular lines will also be reproduced.
     
  4. Matthew Rusbarsky

    Matthew Rusbarsky Member

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    Not true. A fresnel lens (like most other lenses) has a focal length. You can use it for enlarging, but not for a contact print.
     
  5. Gerald C Koch

    Gerald C Koch Member

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    Sorry but you are wrong. http://science.howstuffworks.com/question244.htm

    Fresnel lenses can be used in enlargers but only between the light source and the negative. As I said they are not good for imaging.
     
  6. E76

    E76 Member

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    Umm, fresnel lenses can and have been used for imaging! They bring rays of light to a single point of focus, forming a real image, and they do have a focal length. Like all lenses the quality of the image depends on the quality of manufacture and most fresnel lenses are not built to very high standards. In this regard they are not very useful for imaging. Other than that, there's no reason why you can't use one!
     
  7. holmburgers

    holmburgers Member

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    All I can say is that they do indeed form an image. I think it'd be cool to make a fresnel lens camera.

    Someone with a Anniversary Graphic (focal plan shutter) should make a glass lensboard with a fresnel mounted to it. :D
     
  8. jorj

    jorj Member

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    I've used a cheap fresnel as part of a box camera. Works fine, if a bit difficult to focus - the reading magnifier I used had a very short focal length, making it very sensitive...
     
  9. Gerald C Koch

    Gerald C Koch Member

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    The following quotation is from one of the many web sites discussing the use of Fresnel lenses. "Even though each groove or facet brings light precisely to a focus, the breaking up of the wavefront by the discontinuous surface of a Fresnel lens degrades the visible image quality. ... Fresnel lenses are usually not recommended for imaging applications in the visible light region of the spectrum".

    You could use a Fresnel lens of very high quality but the image is still degraded. You can ignore civil laws but you cannot ignore the laws of optics. I could post many more quotations but what would be the point.
     
    Last edited by a moderator: Jul 25, 2011
  10. michaelbsc

    michaelbsc Member

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    So the answer is "Yes it will work."

    Not well, but it will work. For that matter, a lawn mower can be used as transportation device. It isn't a good fit, but it will work.

    I rather like Chris's idea to make a fresnel "lensboard" for a Speed. Might be better than a Holga.
     
  11. mabman

    mabman Member

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    Interesting. As it happens I also have an (ugly, but functional) Graphic w/ focal plane shutter that I planned to make a pinhole for, but haven't gotten around to it yet...
     
  12. michaelbsc

    michaelbsc Member

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    I think Jorj point that the sheet lenses you find in book stores have a short focal length isn't to be ignored.

    Wonder where you could find them with longer focal lengths? Of course that would kind of defeat the light gathering function, so that's probably not a desired characteristic for most lens makers.

    And with an aperture the size of a graphic lensboard the light falloff would probably be horrific.

    Still might beat a Holga.
     
  13. Ottrdaemmerung

    Ottrdaemmerung Member

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    Would such a fresnel sheet be useful for placing in front of the ground glass of a view camera to enhance it?
     
  14. holmburgers

    holmburgers Member

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    *thumbs up* :D

    Terry, by many accounts these magnifiers work quite well for enhancing a ground-glass. I'll be trying soon, but haven't gotten around to it. There's a thread here that discusses it.
     
  15. TimmyMac

    TimmyMac Subscriber

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    Huh?

    Aren't fresnel lenses used in multi-kilobuck Canon green ring lenses?
     
  16. Gerald C Koch

    Gerald C Koch Member

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    The Canon lenses use a multilayer diffractive optical element. The pattern seen through a DO lens may look similar to that of a Fresnel lens but other patterns other than concentric rings are also used. Diffractive elements are thin phase elements that operate by means of interference and diffraction to produce arbitrary distributions of light or to aid in the design of optical systems. A pattern is etched onto the surface of the DO element and is only a wavelength or two deep. In a Fresnel lens, the rings are much, much deeper and they work by refraction rather than diffraction. So the Canon DO lenses do not use a Fresnel element.
     
  17. Gerald C Koch

    Gerald C Koch Member

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    The Fresnel lens was invented by a frenchman by the name of Augustine Jean Fresnel in 1822. Its purpose was to concentrate the light from lighthouses and make them more effective in warning ships.

    An interesting fact, in pronouncing his name and the name of the lens he invented the 's' is silent so it is pronounced "frenel". The french appear to have an aversion to the sound of 's' in some words. This can be seen in many cognates. For example, ecole, foret, arret; the English words being school, forest, and arrest or stop.
     
    Last edited by a moderator: Jul 29, 2011