small aperture test

Discussion in 'Digital Photography' started by Dudley Hanks, Nov 4, 2009.

  1. Dudley Hanks

    Dudley Hanks Guest

    Dudley Hanks, Nov 4, 2009
    #1
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  2. "Dudley Hanks" <> wrote in message news:4U9Im.50459$Db2.29545@edtnps83...
    >
    > I've heard a lot about how the cropped sensor cameras are defraction
    > limited to around f/8 - f/11, so I thought I'd see what kind of an image
    > my XSi puts out at a small aperture.
    >
    > I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
    > with a shutter speed of 1 sec.
    >
    > How did it turn out?
    >
    > http://www.snaps.blind-apertures.ca/images/SmallWinterPortrait.jpg
    > (quick download)
    >
    > http://www.snaps.blind-apertures.ca/images/SelfPortraitWinter.jpg (full
    > size)
    >
    > Take Care,
    > Dudley


    Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
    loathe), so there could be some diffraction visible, but I'm also not
    convinced that the subject didn't move within the 1 second exposure!

    Cheers,
    David
    David J Taylor, Nov 4, 2009
    #2
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  3. Dudley Hanks

    Dudley Hanks Guest

    "David J Taylor"
    <-this-bit.nor-this.co.uk.invalid> wrote in
    message news:t6aIm.1501$...
    > "Dudley Hanks" <> wrote in message news:4U9Im.50459$Db2.29545@edtnps83...
    >>
    >> I've heard a lot about how the cropped sensor cameras are defraction
    >> limited to around f/8 - f/11, so I thought I'd see what kind of an image
    >> my XSi puts out at a small aperture.
    >>
    >> I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
    >> with a shutter speed of 1 sec.
    >>
    >> How did it turn out?
    >>
    >> http://www.snaps.blind-apertures.ca/images/SmallWinterPortrait.jpg (quick
    >> download)
    >>
    >> http://www.snaps.blind-apertures.ca/images/SelfPortraitWinter.jpg (full
    >> size)
    >>
    >> Take Care,
    >> Dudley

    >
    > Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
    > loathe), so there could be some diffraction visible, but I'm also not
    > convinced that the subject didn't move within the 1 second exposure!
    >
    > Cheers,
    > David


    Thanks, David, I'll try it again with an inanimate object, or a faster
    shutter speed.

    I suppose, if the test is to be useful, I should also take an equivalent pic
    of the subject using a wider aperture so the two images can be compared.

    Take Care,
    Dudley
    Dudley Hanks, Nov 4, 2009
    #3
  4. "Dudley Hanks" <> wrote in message
    news:DvaIm.50463$Db2.1880@edtnps83...
    []
    > Thanks, David, I'll try it again with an inanimate object, or a faster
    > shutter speed.
    >
    > I suppose, if the test is to be useful, I should also take an equivalent
    > pic of the subject using a wider aperture so the two images can be
    > compared.
    >
    > Take Care,
    > Dudley


    Indeed, yes. Tripod and very careful focussing come to mind. While the
    degradation due to diffraction at f/22 is noticeable with careful
    inspection, you probably wouldn't notice with normal use - just sharpen a
    little more. Diffraction on small sensor cameras is one reason why some
    of them are limited to f/8 or f/11 as the smallest aperture.

    Cheers,
    David
    David J Taylor, Nov 4, 2009
    #4
  5. Dudley Hanks

    Ofnuts Guest

    David J Taylor wrote:
    >
    > "Dudley Hanks" <> wrote in message
    > news:DvaIm.50463$Db2.1880@edtnps83...
    > []
    >> Thanks, David, I'll try it again with an inanimate object, or a faster
    >> shutter speed.
    >>
    >> I suppose, if the test is to be useful, I should also take an
    >> equivalent pic of the subject using a wider aperture so the two images
    >> can be compared.
    >>
    >> Take Care,
    >> Dudley

    >
    > Indeed, yes. Tripod and very careful focussing come to mind. While the
    > degradation due to diffraction at f/22 is noticeable with careful
    > inspection, you probably wouldn't notice with normal use - just sharpen
    > a little more. Diffraction on small sensor cameras is one reason why
    > some of them are limited to f/8 or f/11 as the smallest aperture.
    >


    Some of them haven't even got diaphragm and the "diaphragm" is simulated
    with a neutral filter.

    --
    Bertrand
    Ofnuts, Nov 4, 2009
    #5
  6. Dudley Hanks

    Rich Guest

    On Nov 4, 2:17 am, "Dudley Hanks" <> wrote:
    > I've heard a lot about how the cropped sensor cameras are defraction limited
    > to around f/8 - f/11, so I thought I'd see what kind of an image my XSi puts
    > out at a small aperture.
    >
    > I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
    > with a shutter speed of 1 sec.
    >
    > How did it turn out?
    >
    > http://www.snaps.blind-apertures.ca/images/SmallWinterPortrait.jpg (quick
    > download)
    >
    > http://www.snaps.blind-apertures.ca/images/SelfPortraitWinter.jpg (full
    > size)
    >
    > Take Care,
    > Dudley


    With an APS-C sensor, you would lose about 1/2 your resolution
    (provided the lens is good) going from f8 to f22.
    Rich, Nov 4, 2009
    #6
  7. Dudley Hanks <> wrote:

    > "David J Taylor"
    > <-this-bit.nor-this.co.uk.invalid> wrote in
    > message news:t6aIm.1501$...
    >> "Dudley Hanks" <> wrote in message news:4U9Im.50459$Db2.29545@edtnps83...
    >>>
    >>> I've heard a lot about how the cropped sensor cameras are defraction
    >>> limited to around f/8 - f/11, so I thought I'd see what kind of an image
    >>> my XSi puts out at a small aperture.
    >>>
    >>> I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
    >>> with a shutter speed of 1 sec.
    >>>
    >>> How did it turn out?
    >>>
    >>> http://www.snaps.blind-apertures.ca/images/SmallWinterPortrait.jpg (quick
    >>> download)
    >>>
    >>> http://www.snaps.blind-apertures.ca/images/SelfPortraitWinter.jpg (full
    >>> size)
    >>>
    >>> Take Care,
    >>> Dudley

    >>
    >> Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
    >> loathe), so there could be some diffraction visible, but I'm also not
    >> convinced that the subject didn't move within the 1 second exposure!
    >>
    >> Cheers,
    >> David


    > Thanks, David, I'll try it again with an inanimate object, or a faster
    > shutter speed.


    > I suppose, if the test is to be useful, I should also take an equivalent pic
    > of the subject using a wider aperture so the two images can be compared.


    The diffraction limit of aperture is usually taken to be the last
    aperture in a decreasing series of sharper apertures, i.e., stopping
    down further makes the image softer because of diffraction. But that's
    not a fixed aperture, it depends on such things as the exact sensor
    pixel size (or crop factor) not just the nominal "1.5", on the
    resolution of the lens, and whether you're looking at the centre of
    the image or the edges or some compromise between the two. Why
    should it depend on those? Because the point at which an extra stop's
    worth of diffraction softening becomes larger than how much other
    kinds of lens aberration are being improved by stopping down obviously
    will depend on the size of those other errors. In other words better
    lenses will have larger sharpest apertures.

    I find for example on my Sony A350 that my general purpose zoom is
    usually sharpest at f8, but at its soft extremes that becomes f11, and
    my 50mm prime is sharpest at f5.6.

    This can only be established for your camera and each of your lenses
    by taking a comparative series of shots while varying the aperture. On
    zooms it may change with focal length.

    --
    Chris Malcolm
    Chris Malcolm, Nov 4, 2009
    #7
  8. Dudley Hanks

    Dudley Hanks Guest

    "Chris Malcolm" <> wrote in message
    news:...
    > Dudley Hanks <> wrote:
    >
    >> "David J Taylor"
    >> <-this-bit.nor-this.co.uk.invalid> wrote in
    >> message news:t6aIm.1501$...
    >>> "Dudley Hanks" <> wrote in message
    >>> news:4U9Im.50459$Db2.29545@edtnps83...
    >>>>
    >>>> I've heard a lot about how the cropped sensor cameras are defraction
    >>>> limited to around f/8 - f/11, so I thought I'd see what kind of an
    >>>> image
    >>>> my XSi puts out at a small aperture.
    >>>>
    >>>> I snapped on my 50mm f/1.8 lens and set it up to take a picture at
    >>>> f/22,
    >>>> with a shutter speed of 1 sec.
    >>>>
    >>>> How did it turn out?
    >>>>
    >>>> http://www.snaps.blind-apertures.ca/images/SmallWinterPortrait.jpg
    >>>> (quick
    >>>> download)
    >>>>
    >>>> http://www.snaps.blind-apertures.ca/images/SelfPortraitWinter.jpg
    >>>> (full
    >>>> size)
    >>>>
    >>>> Take Care,
    >>>> Dudley
    >>>
    >>> Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
    >>> loathe), so there could be some diffraction visible, but I'm also not
    >>> convinced that the subject didn't move within the 1 second exposure!
    >>>
    >>> Cheers,
    >>> David

    >
    >> Thanks, David, I'll try it again with an inanimate object, or a faster
    >> shutter speed.

    >
    >> I suppose, if the test is to be useful, I should also take an equivalent
    >> pic
    >> of the subject using a wider aperture so the two images can be compared.

    >
    > The diffraction limit of aperture is usually taken to be the last
    > aperture in a decreasing series of sharper apertures, i.e., stopping
    > down further makes the image softer because of diffraction. But that's
    > not a fixed aperture, it depends on such things as the exact sensor
    > pixel size (or crop factor) not just the nominal "1.5", on the
    > resolution of the lens, and whether you're looking at the centre of
    > the image or the edges or some compromise between the two. Why
    > should it depend on those? Because the point at which an extra stop's
    > worth of diffraction softening becomes larger than how much other
    > kinds of lens aberration are being improved by stopping down obviously
    > will depend on the size of those other errors. In other words better
    > lenses will have larger sharpest apertures.
    >
    > I find for example on my Sony A350 that my general purpose zoom is
    > usually sharpest at f8, but at its soft extremes that becomes f11, and
    > my 50mm prime is sharpest at f5.6.
    >
    > This can only be established for your camera and each of your lenses
    > by taking a comparative series of shots while varying the aperture. On
    > zooms it may change with focal length.
    >
    > --
    > Chris Malcolm


    Thanks, Chris, that's good info to have.

    This is a pretty cheap lens, and I think its a bit soft to begin with.

    I've always been a fan of mildly soft portraits, and this lens has worked
    well for that purpose. But its also given me a few nice and sharp pics as
    well.

    It'll be interesting to see how it performs across its full range...

    Take Care,
    Dudley
    Dudley Hanks, Nov 4, 2009
    #8
  9. Dudley Hanks

    Better Info Guest

    On 4 Nov 2009 17:49:36 GMT, Chris Malcolm <> wrote:

    >Dudley Hanks <> wrote:
    >
    >> "David J Taylor"
    >> <-this-bit.nor-this.co.uk.invalid> wrote in
    >> message news:t6aIm.1501$...
    >>> "Dudley Hanks" <> wrote in message news:4U9Im.50459$Db2.29545@edtnps83...
    >>>>
    >>>> I've heard a lot about how the cropped sensor cameras are defraction
    >>>> limited to around f/8 - f/11, so I thought I'd see what kind of an image
    >>>> my XSi puts out at a small aperture.
    >>>>
    >>>> I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
    >>>> with a shutter speed of 1 sec.
    >>>>
    >>>> How did it turn out?
    >>>>
    >>>> http://www.snaps.blind-apertures.ca/images/SmallWinterPortrait.jpg (quick
    >>>> download)
    >>>>
    >>>> http://www.snaps.blind-apertures.ca/images/SelfPortraitWinter.jpg (full
    >>>> size)
    >>>>
    >>>> Take Care,
    >>>> Dudley
    >>>
    >>> Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
    >>> loathe), so there could be some diffraction visible, but I'm also not
    >>> convinced that the subject didn't move within the 1 second exposure!
    >>>
    >>> Cheers,
    >>> David

    >
    >> Thanks, David, I'll try it again with an inanimate object, or a faster
    >> shutter speed.

    >
    >> I suppose, if the test is to be useful, I should also take an equivalent pic
    >> of the subject using a wider aperture so the two images can be compared.

    >
    >The diffraction limit of aperture is usually taken to be the last
    >aperture in a decreasing series of sharper apertures, i.e., stopping
    >down further makes the image softer because of diffraction. But that's
    >not a fixed aperture, it depends on such things as the exact sensor
    >pixel size (or crop factor) not just the nominal "1.5", on the
    >resolution of the lens, and whether you're looking at the centre of
    >the image or the edges or some compromise between the two. Why
    >should it depend on those? Because the point at which an extra stop's
    >worth of diffraction softening becomes larger than how much other
    >kinds of lens aberration are being improved by stopping down obviously
    >will depend on the size of those other errors. In other words better
    >lenses will have larger sharpest apertures.
    >
    >I find for example on my Sony A350 that my general purpose zoom is
    >usually sharpest at f8, but at its soft extremes that becomes f11, and
    >my 50mm prime is sharpest at f5.6.
    >
    >This can only be established for your camera and each of your lenses
    >by taking a comparative series of shots while varying the aperture. On
    >zooms it may change with focal length.


    Your test won't work. Unless the widest aperture of your lens is the very
    sharpest, that means that the lens is not of diffraction-limited quality,
    the very best there is. If you lose detail at any time that you open up the
    lens, then that means the lens is not diffraction-limited. If it's not
    diffraction limited you can't tell when diffraction is what is causing the
    softening. As in all DSLR glass, the softening you see is due to lenses not
    being of diffraction-limited quality, poor lens manufacturing. Usually only
    one stop is adequate because the defects are overridden by that particular
    aperture stop. Anything above and below it is showing lens-figure defects,
    not diffraction problems.
    Better Info, Nov 4, 2009
    #9
  10. Better Info <> wrote:
    > On 4 Nov 2009 17:49:36 GMT, Chris Malcolm <> wrote:


    >>The diffraction limit of aperture is usually taken to be the last
    >>aperture in a decreasing series of sharper apertures, i.e., stopping
    >>down further makes the image softer because of diffraction. But that's
    >>not a fixed aperture, it depends on such things as the exact sensor
    >>pixel size (or crop factor) not just the nominal "1.5", on the
    >>resolution of the lens, and whether you're looking at the centre of
    >>the image or the edges or some compromise between the two. Why
    >>should it depend on those? Because the point at which an extra stop's
    >>worth of diffraction softening becomes larger than how much other
    >>kinds of lens aberration are being improved by stopping down obviously
    >>will depend on the size of those other errors. In other words better
    >>lenses will have larger sharpest apertures.
    >>
    >>I find for example on my Sony A350 that my general purpose zoom is
    >>usually sharpest at f8, but at its soft extremes that becomes f11, and
    >>my 50mm prime is sharpest at f5.6.
    >>
    >>This can only be established for your camera and each of your lenses
    >>by taking a comparative series of shots while varying the aperture. On
    >>zooms it may change with focal length.


    > Your test won't work. Unless the widest aperture of your lens is the very
    > sharpest, that means that the lens is not of diffraction-limited quality,
    > the very best there is. If you lose detail at any time that you open up the
    > lens, then that means the lens is not diffraction-limited.


    You've got it back to front. Since diffraction increases as the lens
    is stopped because because of the change of proportion of lens area to
    lens circumference, the test works for all cases EXCEPT when the
    widest aperture is sharpest.

    > If it's not
    > diffraction limited you can't tell when diffraction is what is causing the
    > softening. As in all DSLR glass, the softening you see is due to lenses not
    > being of diffraction-limited quality, poor lens manufacturing.


    That's true when the aperture is wider than the diffraction limited
    aperture, and false when it's smaller. The point you're missing is
    that lens aberrations reduce as the lens stops down, because a higher
    proportion of the image is coming from less refracted parts of the
    lens, but as you stop down the proportion of diffraction increases,
    because the diffraction proportion is related to the
    area/circumference proportion of the aperture. So in any
    non-diffraction-limited lens there will be an aperture where the
    improving of lens defects by stopping down is overtaken by the
    worsening of diffraction effects.

    --
    Chris Malcolm
    Chris Malcolm, Nov 5, 2009
    #10
  11. On 5 Nov 2009 02:02:28 GMT, Chris Malcolm <> wrote:

    >
    >You've got it back to front. Since diffraction increases as the lens
    >is stopped because because of the change of proportion of lens area to
    >lens circumference, the test works for all cases EXCEPT when the
    >widest aperture is sharpest.


    Go educate your useless **** of an ignorant moron troll self. Resolution
    increases with objective optics diameter. IF those optics are of
    diffraction limited quality.
    Educationg Trolls Is An Endless Task, Nov 5, 2009
    #11
  12. Dudley Hanks

    Paul Furman Guest

    Dudley Hanks wrote:
    > I've heard a lot about how the cropped sensor cameras are defraction limited
    > to around f/8 - f/11, so I thought I'd see what kind of an image my XSi puts
    > out at a small aperture.
    >
    > I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
    > with a shutter speed of 1 sec.
    >
    > How did it turn out?


    The only way to know is to do a test in series. It looks soft to me.
    Sometimes that's OK though, sometimes DOF is more important. This photo:
    http://www.flickr.com/photos/edgehill/4075980407
    had DOF as a priority though I didn't exceed the diffraction limits and
    the lens is near optimum wide open. The power lines in the upper left
    are soft due to tilting the focus plane.


    > http://www.snaps.blind-apertures.ca/images/SmallWinterPortrait.jpg (quick
    > download)
    >
    > http://www.snaps.blind-apertures.ca/images/SelfPortraitWinter.jpg (full
    > size)
    >
    > Take Care,
    > Dudley
    >
    >



    --
    Paul Furman
    www.edgehill.net
    www.baynatives.com

    all google groups messages filtered due to spam
    Paul Furman, Nov 5, 2009
    #12
  13. Dudley Hanks

    Bob Larter Guest

    Dudley Hanks wrote:
    > "Chris Malcolm" <> wrote in message
    > news:...
    >> Dudley Hanks <> wrote:
    >>
    >>> "David J Taylor"
    >>> <-this-bit.nor-this.co.uk.invalid> wrote in
    >>> message news:t6aIm.1501$...
    >>>> "Dudley Hanks" <> wrote in message
    >>>> news:4U9Im.50459$Db2.29545@edtnps83...
    >>>>> I've heard a lot about how the cropped sensor cameras are defraction
    >>>>> limited to around f/8 - f/11, so I thought I'd see what kind of an
    >>>>> image
    >>>>> my XSi puts out at a small aperture.
    >>>>>
    >>>>> I snapped on my 50mm f/1.8 lens and set it up to take a picture at
    >>>>> f/22,
    >>>>> with a shutter speed of 1 sec.
    >>>>>
    >>>>> How did it turn out?
    >>>>>
    >>>>> http://www.snaps.blind-apertures.ca/images/SmallWinterPortrait.jpg
    >>>>> (quick
    >>>>> download)
    >>>>>
    >>>>> http://www.snaps.blind-apertures.ca/images/SelfPortraitWinter.jpg
    >>>>> (full
    >>>>> size)
    >>>>>
    >>>>> Take Care,
    >>>>> Dudley
    >>>> Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
    >>>> loathe), so there could be some diffraction visible, but I'm also not
    >>>> convinced that the subject didn't move within the 1 second exposure!
    >>>>
    >>>> Cheers,
    >>>> David
    >>> Thanks, David, I'll try it again with an inanimate object, or a faster
    >>> shutter speed.
    >>> I suppose, if the test is to be useful, I should also take an equivalent
    >>> pic
    >>> of the subject using a wider aperture so the two images can be compared.

    >> The diffraction limit of aperture is usually taken to be the last
    >> aperture in a decreasing series of sharper apertures, i.e., stopping
    >> down further makes the image softer because of diffraction. But that's
    >> not a fixed aperture, it depends on such things as the exact sensor
    >> pixel size (or crop factor) not just the nominal "1.5", on the
    >> resolution of the lens, and whether you're looking at the centre of
    >> the image or the edges or some compromise between the two. Why
    >> should it depend on those? Because the point at which an extra stop's
    >> worth of diffraction softening becomes larger than how much other
    >> kinds of lens aberration are being improved by stopping down obviously
    >> will depend on the size of those other errors. In other words better
    >> lenses will have larger sharpest apertures.
    >>
    >> I find for example on my Sony A350 that my general purpose zoom is
    >> usually sharpest at f8, but at its soft extremes that becomes f11, and
    >> my 50mm prime is sharpest at f5.6.
    >>
    >> This can only be established for your camera and each of your lenses
    >> by taking a comparative series of shots while varying the aperture. On
    >> zooms it may change with focal length.
    >>
    >> --
    >> Chris Malcolm

    >
    > Thanks, Chris, that's good info to have.
    >
    > This is a pretty cheap lens, and I think its a bit soft to begin with.


    The 50mm/F1.8II is a surprisingly good lens for the money. I've taken a
    lot of excellent shots with mine, so please don't sell it short!
    I've since 'upgraded' to a 50mm/F1.4, but it's not as much of an
    improvement as you might expect from the price difference.


    --
    W
    . | ,. w , "Some people are alive only because
    \|/ \|/ it is illegal to kill them." Perna condita delenda est
    ---^----^---------------------------------------------------------------
    Bob Larter, Nov 5, 2009
    #13
  14. Dudley Hanks

    Bob Larter Guest

    Better Info wrote:
    > On 4 Nov 2009 17:49:36 GMT, Chris Malcolm <> wrote:
    >
    >> Dudley Hanks <> wrote:
    >>
    >>> "David J Taylor"
    >>> <-this-bit.nor-this.co.uk.invalid> wrote in
    >>> message news:t6aIm.1501$...
    >>>> "Dudley Hanks" <> wrote in message news:4U9Im.50459$Db2.29545@edtnps83...
    >>>>> I've heard a lot about how the cropped sensor cameras are defraction
    >>>>> limited to around f/8 - f/11, so I thought I'd see what kind of an image
    >>>>> my XSi puts out at a small aperture.
    >>>>>
    >>>>> I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
    >>>>> with a shutter speed of 1 sec.
    >>>>>
    >>>>> How did it turn out?
    >>>>>
    >>>>> http://www.snaps.blind-apertures.ca/images/SmallWinterPortrait.jpg (quick
    >>>>> download)
    >>>>>
    >>>>> http://www.snaps.blind-apertures.ca/images/SelfPortraitWinter.jpg (full
    >>>>> size)
    >>>>>
    >>>>> Take Care,
    >>>>> Dudley
    >>>> Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
    >>>> loathe), so there could be some diffraction visible, but I'm also not
    >>>> convinced that the subject didn't move within the 1 second exposure!
    >>>>
    >>>> Cheers,
    >>>> David
    >>> Thanks, David, I'll try it again with an inanimate object, or a faster
    >>> shutter speed.
    >>> I suppose, if the test is to be useful, I should also take an equivalent pic
    >>> of the subject using a wider aperture so the two images can be compared.

    >> The diffraction limit of aperture is usually taken to be the last
    >> aperture in a decreasing series of sharper apertures, i.e., stopping
    >> down further makes the image softer because of diffraction. But that's
    >> not a fixed aperture, it depends on such things as the exact sensor
    >> pixel size (or crop factor) not just the nominal "1.5", on the
    >> resolution of the lens, and whether you're looking at the centre of
    >> the image or the edges or some compromise between the two. Why
    >> should it depend on those? Because the point at which an extra stop's
    >> worth of diffraction softening becomes larger than how much other
    >> kinds of lens aberration are being improved by stopping down obviously
    >> will depend on the size of those other errors. In other words better
    >> lenses will have larger sharpest apertures.
    >>
    >> I find for example on my Sony A350 that my general purpose zoom is
    >> usually sharpest at f8, but at its soft extremes that becomes f11, and
    >> my 50mm prime is sharpest at f5.6.
    >>
    >> This can only be established for your camera and each of your lenses
    >> by taking a comparative series of shots while varying the aperture. On
    >> zooms it may change with focal length.

    >
    > Your test won't work.


    Please, get back to us when you grow a clue. Bye!


    --
    W
    . | ,. w , "Some people are alive only because
    \|/ \|/ it is illegal to kill them." Perna condita delenda est
    ---^----^---------------------------------------------------------------
    Bob Larter, Nov 5, 2009
    #14
  15. Dudley Hanks

    Bryan Guest

    Dudley Hanks wrote:
    > I've heard a lot about how the cropped sensor cameras are defraction limited
    > to around f/8 - f/11, so I thought I'd see what kind of an image my XSi puts
    > out at a small aperture.
    >
    > I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
    > with a shutter speed of 1 sec.
    >
    > How did it turn out?

    [...]
    > http://www.snaps.blind-apertures.ca/images/SelfPortraitWinter.jpg (full
    > size)


    I'll go farther than previous respondents: That photo, from a Canon
    XSi at f/22, is obviously not diffraction limited.

    The statements you'll hear of the diffraction limit assume everything
    else it practically optimal: rock-steady subject, tripod mount,
    perfect focus, and unless the claim is about a particular lens, they
    mean a laudably sharp one.
    Bryan, Nov 5, 2009
    #15
  16. Dudley Hanks

    Martin Brown Guest

    Dudley Hanks wrote:
    > "David J Taylor"
    > <-this-bit.nor-this.co.uk.invalid> wrote in
    > message news:t6aIm.1501$...
    >> "Dudley Hanks" <> wrote in message news:4U9Im.50459$Db2.29545@edtnps83...
    >>> I've heard a lot about how the cropped sensor cameras are defraction
    >>> limited to around f/8 - f/11, so I thought I'd see what kind of an image
    >>> my XSi puts out at a small aperture.
    >>>
    >>> I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
    >>> with a shutter speed of 1 sec.
    >>>
    >>> How did it turn out?
    >>>
    >>> http://www.snaps.blind-apertures.ca/images/SmallWinterPortrait.jpg (quick
    >>> download)
    >>>
    >>> http://www.snaps.blind-apertures.ca/images/SelfPortraitWinter.jpg (full
    >>> size)
    >>>
    >>> Take Care,
    >>> Dudley

    >> Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
    >> loathe), so there could be some diffraction visible, but I'm also not
    >> convinced that the subject didn't move within the 1 second exposure!
    >>

    > Thanks, David, I'll try it again with an inanimate object, or a faster
    > shutter speed.
    >
    > I suppose, if the test is to be useful, I should also take an equivalent pic
    > of the subject using a wider aperture so the two images can be compared.


    If you are serious about being able to tell include a few ball bearings
    on black velvet in the picture composition. Specular highlights are
    about the easiest thing to see if an image is diffraction limited.

    Or you could just use a pinhole over the lens and a verry long exposure.

    Regards,
    Martin Brown
    Martin Brown, Nov 5, 2009
    #16
  17. Dudley Hanks

    Dudley Hanks Guest

    "Bob Larter" <> wrote in message
    news:4af2c78c$...
    > Dudley Hanks wrote:
    >> "Chris Malcolm" <> wrote in message
    >> news:...
    >>> Dudley Hanks <> wrote:
    >>>
    >>>> "David J Taylor"
    >>>> <-this-bit.nor-this.co.uk.invalid> wrote in
    >>>> message news:t6aIm.1501$...
    >>>>> "Dudley Hanks" <> wrote in message
    >>>>> news:4U9Im.50459$Db2.29545@edtnps83...
    >>>>>> I've heard a lot about how the cropped sensor cameras are defraction
    >>>>>> limited to around f/8 - f/11, so I thought I'd see what kind of an
    >>>>>> image
    >>>>>> my XSi puts out at a small aperture.
    >>>>>>
    >>>>>> I snapped on my 50mm f/1.8 lens and set it up to take a picture at
    >>>>>> f/22,
    >>>>>> with a shutter speed of 1 sec.
    >>>>>>
    >>>>>> How did it turn out?
    >>>>>>
    >>>>>> http://www.snaps.blind-apertures.ca/images/SmallWinterPortrait.jpg
    >>>>>> (quick
    >>>>>> download)
    >>>>>>
    >>>>>> http://www.snaps.blind-apertures.ca/images/SelfPortraitWinter.jpg
    >>>>>> (full
    >>>>>> size)
    >>>>>>
    >>>>>> Take Care,
    >>>>>> Dudley
    >>>>> Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
    >>>>> loathe), so there could be some diffraction visible, but I'm also not
    >>>>> convinced that the subject didn't move within the 1 second exposure!
    >>>>>
    >>>>> Cheers,
    >>>>> David
    >>>> Thanks, David, I'll try it again with an inanimate object, or a faster
    >>>> shutter speed.
    >>>> I suppose, if the test is to be useful, I should also take an
    >>>> equivalent pic
    >>>> of the subject using a wider aperture so the two images can be
    >>>> compared.
    >>> The diffraction limit of aperture is usually taken to be the last
    >>> aperture in a decreasing series of sharper apertures, i.e., stopping
    >>> down further makes the image softer because of diffraction. But that's
    >>> not a fixed aperture, it depends on such things as the exact sensor
    >>> pixel size (or crop factor) not just the nominal "1.5", on the
    >>> resolution of the lens, and whether you're looking at the centre of
    >>> the image or the edges or some compromise between the two. Why
    >>> should it depend on those? Because the point at which an extra stop's
    >>> worth of diffraction softening becomes larger than how much other
    >>> kinds of lens aberration are being improved by stopping down obviously
    >>> will depend on the size of those other errors. In other words better
    >>> lenses will have larger sharpest apertures.
    >>>
    >>> I find for example on my Sony A350 that my general purpose zoom is
    >>> usually sharpest at f8, but at its soft extremes that becomes f11, and
    >>> my 50mm prime is sharpest at f5.6.
    >>>
    >>> This can only be established for your camera and each of your lenses
    >>> by taking a comparative series of shots while varying the aperture. On
    >>> zooms it may change with focal length.
    >>>
    >>> --
    >>> Chris Malcolm

    >>
    >> Thanks, Chris, that's good info to have.
    >>
    >> This is a pretty cheap lens, and I think its a bit soft to begin with.

    >
    > The 50mm/F1.8II is a surprisingly good lens for the money. I've taken a
    > lot of excellent shots with mine, so please don't sell it short!
    > I've since 'upgraded' to a 50mm/F1.4, but it's not as much of an
    > improvement as you might expect from the price difference.



    Originally, I bought it for my Canon A2, but didn't use it a lot. I used it
    a bit for blurred background shots of the kids, flowers, etc.

    However, with the crop factor of the XSi, it's now a great portrait lens,
    and it still has a fairly respectable aperture when I add in my 2x
    converter, giving me a (35mm equiv) f/3.5 160mm lens.

    I'm finding myself falling back on it a lot these days.

    Take Care,
    Dudley
    Dudley Hanks, Nov 5, 2009
    #17
  18. On Thu, 05 Nov 2009 23:40:44 +1000, Bob Larter <>
    wrote:

    >Better Info wrote:
    >> On 4 Nov 2009 17:49:36 GMT, Chris Malcolm <> wrote:
    >>
    >>> Dudley Hanks <> wrote:
    >>>
    >>>> "David J Taylor"
    >>>> <-this-bit.nor-this.co.uk.invalid> wrote in
    >>>> message news:t6aIm.1501$...
    >>>>> "Dudley Hanks" <> wrote in message news:4U9Im.50459$Db2.29545@edtnps83...
    >>>>>> I've heard a lot about how the cropped sensor cameras are defraction
    >>>>>> limited to around f/8 - f/11, so I thought I'd see what kind of an image
    >>>>>> my XSi puts out at a small aperture.
    >>>>>>
    >>>>>> I snapped on my 50mm f/1.8 lens and set it up to take a picture at f/22,
    >>>>>> with a shutter speed of 1 sec.
    >>>>>>
    >>>>>> How did it turn out?
    >>>>>>
    >>>>>> http://www.snaps.blind-apertures.ca/images/SmallWinterPortrait.jpg (quick
    >>>>>> download)
    >>>>>>
    >>>>>> http://www.snaps.blind-apertures.ca/images/SelfPortraitWinter.jpg (full
    >>>>>> size)
    >>>>>>
    >>>>>> Take Care,
    >>>>>> Dudley
    >>>>> Difficult to say, Dudley. Yes, the image isn't "tack sharp" (a term I
    >>>>> loathe), so there could be some diffraction visible, but I'm also not
    >>>>> convinced that the subject didn't move within the 1 second exposure!
    >>>>>
    >>>>> Cheers,
    >>>>> David
    >>>> Thanks, David, I'll try it again with an inanimate object, or a faster
    >>>> shutter speed.
    >>>> I suppose, if the test is to be useful, I should also take an equivalent pic
    >>>> of the subject using a wider aperture so the two images can be compared.
    >>> The diffraction limit of aperture is usually taken to be the last
    >>> aperture in a decreasing series of sharper apertures, i.e., stopping
    >>> down further makes the image softer because of diffraction. But that's
    >>> not a fixed aperture, it depends on such things as the exact sensor
    >>> pixel size (or crop factor) not just the nominal "1.5", on the
    >>> resolution of the lens, and whether you're looking at the centre of
    >>> the image or the edges or some compromise between the two. Why
    >>> should it depend on those? Because the point at which an extra stop's
    >>> worth of diffraction softening becomes larger than how much other
    >>> kinds of lens aberration are being improved by stopping down obviously
    >>> will depend on the size of those other errors. In other words better
    >>> lenses will have larger sharpest apertures.
    >>>
    >>> I find for example on my Sony A350 that my general purpose zoom is
    >>> usually sharpest at f8, but at its soft extremes that becomes f11, and
    >>> my 50mm prime is sharpest at f5.6.
    >>>
    >>> This can only be established for your camera and each of your lenses
    >>> by taking a comparative series of shots while varying the aperture. On
    >>> zooms it may change with focal length.

    >>
    >> Your test won't work.

    >
    >Please, get back to us when you grow a clue. Bye!



    Bob Larter's legal name: Lionel Lauer
    Home news-group, an actual group in the "troll-tracker" hierarchy:
    alt.kook.lionel-lauer (established on, or before, 2004)
    Registered Description: "the 'owner of several troll domains' needs a group where he'll stay on topic."

    <http://groups.google.com/groups/search?hl=en&num=10&as_ugroup=alt.kook.lionel-lauer>

    "Results 1 - 10 of about 2,170 for group:alt.kook.lionel-lauer."
    Bob Larter is Lionel Lauer - Look it up., Nov 5, 2009
    #18
  19. On Fri, 06 Nov 2009 11:56:53 +1000, Bob Larter <>
    wrote:

    >John Navas wrote:
    >> On Thu, 05 Nov 2009 23:39:40 +1000, Bob Larter <>
    >> wrote in <4af2c78c$>:
    >>
    >>> The 50mm/F1.8II is a surprisingly good lens for the money. I've taken a
    >>> lot of excellent shots with mine, so please don't sell it short!
    >>> I've since 'upgraded' to a 50mm/F1.4, but it's not as much of an
    >>> improvement as you might expect from the price difference.

    >>
    >> What you get for the money with the f/1.4 over the f/1.8 is speed,
    >> not IQ.

    >
    >The f1.4 also has more aperture blades, so the bokeh is a bit nicer as well.


    Post-processing plugins with depth-map masks afford an infinite number of
    aperture blades for bokeh, as well as even emulating catadioptric lens
    systems no matter what camera took the image, and more.

    Catch up, know-nothing snapshooter DSLR-Troll!
    Outing Trolls is FUN!, Nov 6, 2009
    #19
  20. Dudley Hanks

    Bob Larter Guest

    John Navas wrote:
    > On Thu, 05 Nov 2009 23:39:40 +1000, Bob Larter <>
    > wrote in <4af2c78c$>:
    >
    >> The 50mm/F1.8II is a surprisingly good lens for the money. I've taken a
    >> lot of excellent shots with mine, so please don't sell it short!
    >> I've since 'upgraded' to a 50mm/F1.4, but it's not as much of an
    >> improvement as you might expect from the price difference.

    >
    > What you get for the money with the f/1.4 over the f/1.8 is speed,
    > not IQ.


    The f1.4 also has more aperture blades, so the bokeh is a bit nicer as well.

    --
    W
    . | ,. w , "Some people are alive only because
    \|/ \|/ it is illegal to kill them." Perna condita delenda est
    ---^----^---------------------------------------------------------------
    Bob Larter, Nov 6, 2009
    #20
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