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Thread: spherical aberration solved?

  1. #11

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    Re: spherical aberration solved?

    Quote Originally Posted by Mark Sawyer View Post
    Then they've got chromatic aberration, coma, curved field, and distortion to replace the spherical aberration. Yay...
    Yes, of course... this is what it is, an analytic way to calculate asph singlets that are free fom sph aberration, so this is math.

  2. #12
    Drew Wiley
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    Re: spherical aberration solved?

    It all depends on the glass type. Do you saw off the bottom of a Coke bottle or a Pepsi bottle?

  3. #13
    Resident Heretic Bruce Watson's Avatar
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    Re: spherical aberration solved?

    Quote Originally Posted by Mark Sawyer View Post
    For all practical purposes, spherical aberration was eliminated by WWII or earlier. This is sort of like someone saying they've just designed the first apochromatic lens.
    Not with a singlet -- a single piece of glass. It always took at least two, which is perhaps why lenses of the period used so many cemented doublets and triplets.

    What makes this interesting to me is that it can be done with a singlet. Which should allow replacement of a cemented doublet or triplet with a singlet, which should result in a lighter and physically smaller camera lens. Not to mention somewhat better light transmission because of less glass, and less internal reflections because of fewer surfaces, etc. And of course it might be cheaper as well, because less glass even if the singlet is more expensive to make.

    So... lighter, smaller, faster, cheaper. What's not to like?

    Bottom line for me is that I could hike farther, and make photographs where I could not before. And others like me could do the same. And that, might make it worth doing. IDK.

    And lets not leave out the fun of solving an "unsolvable" problem.

    Bruce Watson

  4. #14
    Mark Sawyer's Avatar
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    Re: spherical aberration solved?

    Quote Originally Posted by Bruce Watson View Post
    So... lighter, smaller, faster, cheaper. What's not to like?
    The distortion, curved field, chromatic aberration and coma. Zeroing out one aberration at the expense of ignoring others may be an interesting math problem, but not a practical solution to anything.
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  5. #15
    Resident Heretic Bruce Watson's Avatar
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    Re: spherical aberration solved?

    Quote Originally Posted by Mark Sawyer View Post
    The distortion, curved field, chromatic aberration and coma. Zeroing out one aberration at the expense of ignoring others may be an interesting math problem, but not a practical solution to anything.
    This is the difference between science and engineering. Science is about figuring it out, engineering is about using it to build things. The scientists in this case have figured out how to solve spherical aberration in a singlet. Good on 'em. Really, they've done great work here.

    Engineers haven't yet used this to design lenses AFAIK. Maybe the optical engineers will eventually, maybe not. But if they do, my bet is this will show up first in cell phone cameras, not lenses for us. It may never show up in lenses for LFers.

    Bruce Watson

  6. #16

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    Spherical aberation correction breakthrough reported

    Not that we'll likely see much of this in LF, but it may be of interest to some. It caught my eye today, so I'm passing it along.

    https://www.techspot.com/news/81357-...r-sharper.html
    Philip U.

    Sine scientia ars nihil est. (Without science/knowledge, art is nothing.)
    https://www.flickr.com/photos/156933346@N07/

  7. #17
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    Re: spherical aberration solved?

    Threads merged.

  8. #18
    Nodda Duma's Avatar
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    Re: spherical aberration solved?

    Incorrect. In fact, spherical aberration can be corrected with a single surface. Sir Isaac Newton corrected spherical aberration, lateral color, spherochromatism, astigmatism, and distortion with the paraboloidal surface in the 1600s.

    The single lens of a CD reader corrects spherical aberration entirely.

    Pere is right, this was a well-known academic problem and good for him solving it, but it is purely academic. The physicist worked out a mathematical solution — which is great — for a problem that is solved via other methods every day by lens designers. That’s a great way to earn his doctorate. But in reality it can actually take longer to set up the initial conditions in Zemax or Code V than to run the optimization itself that drives sph ab to zero ..which is not much faster for a simple lens than doing the Seidel coefficient calculations by hand.

    So leading to cheaper, simpler solutions... I shudder at the thought of trying to convince an optical shop to turn a surface like that, or even a molded optics shop to do the same. More expensive and more complex.. definitely.

    Not knocking what he did, don’t get me wrong. I have issue with the sensationalist misleading reporting that followed. It is just a bit too much.




    Quote Originally Posted by Bruce Watson View Post
    Not with a singlet -- a single piece of glass. It always took at least two, which is perhaps why lenses of the period used so many cemented doublets and triplets.

    What makes this interesting to me is that it can be done with a singlet. Which should allow replacement of a cemented doublet or triplet with a singlet, which should result in a lighter and physically smaller camera lens. Not to mention somewhat better light transmission because of less glass, and less internal reflections because of fewer surfaces, etc. And of course it might be cheaper as well, because less glass even if the singlet is more expensive to make.

    So... lighter, smaller, faster, cheaper. What's not to like?

    Bottom line for me is that I could hike farther, and make photographs where I could not before. And others like me could do the same. And that, might make it worth doing. IDK.

    And lets not leave out the fun of solving an "unsolvable" problem.
    Newly made large format dry plates available! Look:
    https://www.etsy.com/shop/Pictoriographica
    .. because my wife is happy when I can cover my photography expenses!

  9. #19
    Jac@stafford.net's Avatar
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    Re: spherical aberration solved?

    Quote Originally Posted by Nodda Duma View Post
    Incorrect. In fact, spherical aberration can be corrected with a single surface. Sir Isaac Newton corrected spherical aberration, lateral color, spherochromatism, astigmatism, and distortion with the paraboloidal surface in the 1600s.
    Half of a regular paraboloid is shown in the picture below. It is an interesting feature from nature.

    For a news story in 1973 I photographed Prof. Riccardo Levi-Setti, University of Chicago, holding a hollow spun aluminum cone-like shape (no lens!) which uses the dimensions of a crab's (or trilobite) eye. It is a poor print reproduction which does not show that at the small end is a cup of water very quickly brought to a boil, even through a dirty window on a bright overcast day.

    He found the dimensions using a scanning ion microscope to discern one cone of a crab's eye
    Picture here.

    More about the professor.

  10. #20
    Nodda Duma's Avatar
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    Re: spherical aberration solved?

    Very cool, jac
    Newly made large format dry plates available! Look:
    https://www.etsy.com/shop/Pictoriographica
    .. because my wife is happy when I can cover my photography expenses!

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