Re: Why are lenses unsharp wide open?

Discussion in 'Digital Photography' started by Bruce, Jul 31, 2011.

  1. Bruce

    Bruce Guest

    Alfred Molon <> wrote:
    >
    >Just wondering - does it come from physics or is it pure economics, i.e.
    >too expensive to make a lens with corner to corner sharpness at F1.4?



    Economics has a big part to play. Many Leica lenses M lenses are
    superbly sharp wide open, but they cost a lot more than more prosaic
    Canon and Nikon glass that performs best when stopped down.

    My current favourite lens is the Leica 24mm f/2.8 Elmarit-M. It is
    sharpest in the centre at f/2.8, and across the whole frame at f/4.
    There is no benefit to sharpness from stopping down any further.
    Bruce, Jul 31, 2011
    #1
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  2. Bruce

    Bruce Guest

    Rich <> wrote:
    >Bruce <> wrote in
    >news::
    >> Alfred Molon <> wrote:
    >>>
    >>>Just wondering - does it come from physics or is it pure economics,

    >i.e.
    >>>too expensive to make a lens with corner to corner sharpness at F1.4?

    >>
    >>
    >> Economics has a big part to play. Many Leica lenses M lenses are
    >> superbly sharp wide open, but they cost a lot more than more prosaic
    >> Canon and Nikon glass that performs best when stopped down.
    >>
    >> My current favourite lens is the Leica 24mm f/2.8 Elmarit-M. It is
    >> sharpest in the centre at f/2.8, and across the whole frame at f/4.
    >> There is no benefit to sharpness from stopping down any further.
    >>
    >>

    >
    >That's enviable performance.



    Enviable indeed. I bought my Leica 24mm f/2.8 Elmarit-M ASPH (I left
    out the ASPH in my previous posting) at a time when Leica prices were
    much lower than they are now. I probably couldn't justify paying
    today's prices.

    At around the same time I bought a Leica 35mm f/1.4 Summilux-M ASPH,
    another outstanding performer. Both lenses are now worth, in Sterling
    terms, somewhere between three and four times what I paid for them. Of
    course Sterling has dropped in value during that time thanks to the
    UK's indebtedness. Even so, these lenses have been a remarkable
    investment. I'm tempted to cash in and buy a Leica M9 body with the
    proceeds, but then I would need some lenses ...


    >One of the shocks you get going from 4/3 to
    >APS or FF is the terrible edge performance of all but the best lenses,
    >wide open anyhow. Using a Zeiss 35mm f2.0 against Nikon's very good but
    >inexpensive 35mm f1.8 was a shock, with the Zeiss being much sharper wide
    >open, and I wouldn't have described the Nikon as bad wide open by any
    >means.



    The Carl Zeiss Distagon 35mm f/2 is a beautiful lens. As long as you
    don't mind focusing manually, it is a far better choice than any 35mm
    lens Nikon has ever made. And if you really need f/1.4, there is the
    outstanding Samyang which is optically marginally superior to the
    spectacularly expensive AF-S Nikkor.

    Of course all these superb lenses are completely wasted on the vast
    majority of buyers who want zoom lenses = preferably with a large zoom
    range so they don't ever have to take them off their cameras - and are
    prepared to accept lousy optical performance in return.

    Pearls before swine ...
    Bruce, Aug 3, 2011
    #2
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  3. Bruce

    Robert Coe Guest

    On Wed, 03 Aug 2011 11:54:20 +0100, Bruce <> wrote:
    : Rich <> wrote:
    : >Bruce <> wrote in
    : >news::
    : >> Alfred Molon <> wrote:
    : >>>
    : >>>Just wondering - does it come from physics or is it pure economics,
    : >i.e.
    : >>>too expensive to make a lens with corner to corner sharpness at F1.4?
    : >>
    : >>
    : >> Economics has a big part to play. Many Leica lenses M lenses are
    : >> superbly sharp wide open, but they cost a lot more than more prosaic
    : >> Canon and Nikon glass that performs best when stopped down.
    : >>
    : >> My current favourite lens is the Leica 24mm f/2.8 Elmarit-M. It is
    : >> sharpest in the centre at f/2.8, and across the whole frame at f/4.
    : >> There is no benefit to sharpness from stopping down any further.
    : >>
    : >>
    : >
    : >That's enviable performance.
    :
    :
    : Enviable indeed. I bought my Leica 24mm f/2.8 Elmarit-M ASPH (I left
    : out the ASPH in my previous posting) at a time when Leica prices were
    : much lower than they are now. I probably couldn't justify paying
    : today's prices.
    :
    : At around the same time I bought a Leica 35mm f/1.4 Summilux-M ASPH,
    : another outstanding performer. Both lenses are now worth, in Sterling
    : terms, somewhere between three and four times what I paid for them. Of
    : course Sterling has dropped in value during that time thanks to the
    : UK's indebtedness. Even so, these lenses have been a remarkable
    : investment. I'm tempted to cash in and buy a Leica M9 body with the
    : proceeds, but then I would need some lenses ...
    :
    :
    : >One of the shocks you get going from 4/3 to
    : >APS or FF is the terrible edge performance of all but the best lenses,
    : >wide open anyhow. Using a Zeiss 35mm f2.0 against Nikon's very good but
    : >inexpensive 35mm f1.8 was a shock, with the Zeiss being much sharper wide
    : >open, and I wouldn't have described the Nikon as bad wide open by any
    : >means.
    :
    :
    : The Carl Zeiss Distagon 35mm f/2 is a beautiful lens. As long as you
    : don't mind focusing manually, it is a far better choice than any 35mm
    : lens Nikon has ever made. And if you really need f/1.4, there is the
    : outstanding Samyang which is optically marginally superior to the
    : spectacularly expensive AF-S Nikkor.
    :
    : Of course all these superb lenses are completely wasted on the vast
    : majority of buyers who want zoom lenses = preferably with a large zoom
    : range so they don't ever have to take them off their cameras - and are
    : prepared to accept lousy optical performance in return.
    :
    : Pearls before swine ...

    But aren't the optical advantages of even a fine prime lens largely wasted if
    you end up having to crop the image to a quarter of its original size because
    you couldn't zoom?

    Of course the standard reply to that question is, "Well, you should zoom with
    your feet." But if there's a river, or a busy highway, or two or three
    referees, or 100 meters of vertical separation in your way, ...

    Bob
    Robert Coe, Aug 4, 2011
    #3
  4. Bruce

    Bruce Guest

    Robert Coe <> wrote:
    >But aren't the optical advantages of even a fine prime lens largely wasted if
    >you end up having to crop the image to a quarter of its original size because
    >you couldn't zoom?
    >
    >Of course the standard reply to that question is, "Well, you should zoom with
    >your feet." But if there's a river, or a busy highway, or two or three
    >referees, or 100 meters of vertical separation in your way, ...



    So that's why so very few good pictures were taken before the
    introduction of zoom lenses. ;-)
    Bruce, Aug 4, 2011
    #4
  5. Robert Coe <> wrote:

    > But aren't the optical advantages of even a fine prime lens largely wasted if
    > you end up having to crop the image to a quarter of its original size because
    > you couldn't zoom?


    Well, that sort of depends on the lenses in question. A 50mm prime
    cropped to 100mm equivalent is worse than a usable zoom at 100mm,
    but a 300mm f/2.8 is vastly better than a 70-300mm f/4-5.6 zoom.
    It's even better than a 70-*2*00mm f/2.8 cropped to 300mm.

    AFAIK tests have shown that a teleconverter + a lens gives a
    better result than just upsampling without the teleconverter ---
    this fits with my own observations.

    How much better a 300mm f/2.8 (or f/4) is than a 70-300mm zoom
    depends a lot on the zoom --- there are cheap consumer zooms and
    even a Canon L zoom in that range, and I bet the L zoom is very
    noticably better than the consumer zoom.


    As to the 50mm lens --- you could try a 2x TC on it and compare
    that against your zoom. Depending on the zoom, the 50mm could
    well come out ahead. (I cannot test that, I don't have bad zooms.)


    > Of course the standard reply to that question is, "Well, you should zoom with
    > your feet." But if there's a river, or a busy highway, or two or three
    > referees, or 100 meters of vertical separation in your way, ...


    Then you'd better pack a more fitting lens the next time.

    OK, you says, I use my 18-270mm. OK, but a 200mm f/2 + 1.4x TC
    beats it. And is better in low light. And if you need more,
    a 200mm f/2 can carry a 2x TC --- and for the mad ones, even a
    1.4x + a 2x works. And should focus. (how good it works depends
    which TC you put closest to the lens.) :)

    -Wolfgang
    Wolfgang Weisselberg, Aug 8, 2011
    #5
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