Anti-shake does work

Discussion in 'Digital SLR' started by RichA, Apr 22, 2005.

  1. RichA

    RichA Guest

    I was in a local camera store and they
    had an anti-shake demonstration setup
    consisting of a vibrating platform
    and a WS flat panel split into two
    sides. The vibration was clearly demonstrated
    with the table on, but the Panasonics they were
    using really did remove the vibration, to a large
    extent. It was impressive.
    Given the 12x zoom of Panasonic's somewhat underbuilt
    camera, they probably figured if they didn't provide
    this feature, people would be returning the camera
    in droves because of blurry shots.
    -Rich
     
    RichA, Apr 22, 2005
    #1
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  2. RichA

    Alan Browne Guest

    I'd like to see the same test with an A1/A2 or Max 7D... I would bet
    that the Panasonic edges out the Minolta's by about a stop of shutter speed.

    A friend (retired photog) has one. I bumped into him at the store a few
    weeks ago. Given the performance of the beastie, it is amazing how
    light and unsubstantial feeling it is...

    Cheers,
    Alan


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    Alan Browne, Apr 22, 2005
    #2
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  3. And, did the anti-shake work?
     
    Ben Rosengart, Apr 22, 2005
    #3
  4. RichA

    RichA Guest

    I just couldn't bring myself to buy something that seemed like it was
    made of the cheapest polystyrene available. But, some of the lenses
    on these camera seem pretty good and the results are decent.
    -Rich
     
    RichA, Apr 22, 2005
    #4
  5. Yes, the anti-shake on the Panasonics works very well indeed.

    David
     
    David J Taylor, Apr 22, 2005
    #5
  6. Alan, I'm unsure what you mean here - are you saying you think the
    Panasonic anti-shake is better than the Minolta? I do wonder if the range
    of the anti-shake on in-the-lens implementation might cover a greater
    offset at the long end of the zoom range than the in-the-camera
    implementation, because of the limited movement of the CCD.

    Cheers,
    David
     
    David J Taylor, Apr 22, 2005
    #6
  7. RichA

    Alan Browne Guest

    I do believe the Panasonic image stab is better than Minolta for the
    simple reason that it (like Canon and Nikon) use an optical element to
    acheive the correction during movement, whereas Minolta move the CCD
    around. I don't believe the Minolta A-S is optically correct during
    correction, where the optical methods are. Since most camera shake is
    pitch and yaw (rotation), moving the CCD in a plane cannot be optically
    correct (IMLTAO). It's also more mass to move (a CCD) so possibly
    bandwidth limited v. the shake being given.

    It has been shown that the Canon and Nikon IS/VR are good for about 2.5
    to 3 stops under "rule-of-thumb" handholding. The Minolta A-S goes to
    about 2 stops. IAC magazine tests have shown mixed results at 2 and 3
    stops slower than "rule of thumb", and more consistant results with the
    Canon and Nikon approach. I do assume that the Panasonic is as good in
    this respect as the Canon and Nikon IS/VR systems.

    A-S is a compromise. I'm happy to have it (though I really haven't
    exercised it fully to find the limits).

    Cheers,
    Alan



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    Alan Browne, Apr 22, 2005
    #7
  8. Alan Browne wrote:
    []
    Thanks, Alan, we are in agreement, then. I do wonder if the A-S in the
    smaller cameras may be even more effective because of the smaller mass of
    the elements. Doubtless they use smaller motors, though! As to moving
    the CCD being optically incorrect, isn't it just a matter of designing the
    lenses to have a larger image circle? You almost get this automatically
    on a less-than-full-frame DSLR.

    I'm completely convinced by A-S, I would not buy a camera without it
    unless there was a very good reason.

    Cheers,
    David
     
    David J Taylor, Apr 23, 2005
    #8
  9. RichA

    mike regish Guest

    You just got me thinking. (Ouch!) Would an IS lens coupled to an IS body
    provide essentially twice the image stabilization? They might enhance each
    other, but they might also be fighting each other. I think they're inertial
    based, but I'm not sure. Some CCDs provide image stabilization by keeping
    the image stable. ie, it's not inertial.

    Any thoughts?

    I took some hand held shots of glowing coals with my 7D. SS 1/4". I was
    sitting and well braced with the lens at about 70mm. Most came out very
    sharp with no discernable shake.

    mike

     
    mike regish, Apr 23, 2005
    #9
  10. First reaction is that they would fight each other like crazy, as they are
    both inertial systems. However, as you hint, adding electronic image
    stabilisation on top of an inertial system should certainly be possible.
    Who's going to be first to demonstrate this?

    Cheers,
    David
     
    David J Taylor, Apr 23, 2005
    #10
  11. RichA

    Clyde Guest


    It doesn't matter what you believe. What is the actual situation? From
    the reviews of the KM 7D that I've read, they say it works as well as
    Canon's and Nikon's.

    Clyde
     
    Clyde, Apr 23, 2005
    #11
  12. RichA

    Alan Browne Guest

    I'm not convinced of this argument because the plane of the sensor is
    being tilted wrt the desired scene focus plane. So moving the sensor
    keeps the image components in the right place but the focus field cannot
    be right. I believe the optical method is more accurate in correction
    in this sense. Also of course, A/S works well at shorter focla lengths
    and not at long. The IS/VR (Canon/Nikon) has the IS for that particular
    lens and its focal lenght(s).

    Cheers,
    Alan


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    Alan Browne, Apr 23, 2005
    #12
  13. RichA

    Alan Browne Guest

    It is inertial. The sensors are not accelerometers, but gyros, but that
    is because the shake is mainly pitch and yaw. The A/S (Minolta) travels
    in a plane movement, however.

    Potentially, if the IS (lens) was rotation correctiong only (gyros), and
    the A/S (body) was plane correcting only (accelerometers) then an
    optimum could be reached as they would be de-coupled (or vert carefully
    coupled).

    Try it on a contrasty/detailled subject in brighter light where your
    shutter speed is at 1/4 of the focal length. (eg: 1/25 for a 100mm
    lens). Shoot 10 frames with A/S.

    I bet your hit rate will be about 50 - 75% for shots that will print at
    8x10.

    Then take that shutter speed down to 1/13 and try again.

    Hit rate will be about 10 - 20% (I'm guessing, haven't tried it).

    Maybe we should have a compiment to the shoot-in, call it the "shake
    down" and see who can produce the sharpest VR/IS/A-S images...

    Cheers,
    Alan.


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    Alan Browne, Apr 23, 2005
    #13
  14. RichA

    Alan Browne Guest

    Please indicate the reviews with links. 'Cause every review I've read
    has put IS/VR about 1 stop better than A-S. My own (less than careful)
    tests with A/S (Max 7D) have shown it to be hit and miss at 3 stops or
    more slower than rule-of-thumb speed.

    Cheers,
    Alan


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    Alan Browne, Apr 23, 2005
    #14
  15. I don't understand what you mean by "tiilted". Isn't it just that the
    image circle of the lens needs to be bigger than the diameter of the
    sensor by the amount of offset that the A/S might produce? And isn't that
    rather neatly achieved by using a less than 35mm full frame sensor, but
    restricting the camera to 35mm lenses? With the optical method, don't you
    have a lens with deliberate optical mis-alignment, i.e. one which will not
    be as sharp unless the offset required for VR is zero?

    If you are seeing about 3 stops allowable speed difference, that's about
    as good as the other methods.

    Cheers,
    David
     
    David J Taylor, Apr 24, 2005
    #15
  16. RichA

    Alan Browne Guest

    If the 'shake movement' was translational and not rotational, I'd agree.
    But most shake is rotation in pitch and yaw where the the A/S is
    correction in translation (y,z [lens axis being x]).
    Not sure. Look at how IS is achieved: a concave-flat lens group is
    inserted in the lens near the nodal point (I believe). It moves in y
    and z [v. lens axiz x], but because of its lens surfaces it naturally
    corrects for a rotational movement. (I think).
    a) I haven't done a controlled study of this. b) the reviews top out
    the Minolta A/S at about 2 stops v. about 3 stops for Canon/Nikon.

    Cheers,
    Alan.


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    Alan Browne, Apr 24, 2005
    #16
  17. Alan, I've not looked into the optical details as deeply as you have. I
    would expect that the angles corrected were so small that rotation and
    translation amounted to the same thing. You have me slightly worried
    about wide-angle A/S (compared to telephoto) though now!

    Cheers,
    David
     
    David J Taylor, Apr 24, 2005
    #17
  18. RichA

    werdan Guest

    How do you figure that 'most shake is rotation in pitch and yaw'?

    If you have one hand under the lens and one on the camera, wouldn't the
    camera be moving up/down left/right at the same rate at front and back so
    the shake would infact be translational?

    I could understand the shake being 'pitch/yaw' if you were talking about a
    compact camera where the hands are on each side so the shake would be a
    tilting and swigning motion
     
    werdan, Apr 24, 2005
    #18
  19. RichA

    Alan Browne Guest

    I haven't looked that deeply. Just my perception of the Canon drawings
    I've seen.
    Be less worried as wide angle, as always, allows for a fairly low
    shutter speed in the first place...

    Cheers,
    Alan


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    Alan Browne, Apr 24, 2005
    #19
  20. RichA

    Alan Browne Guest

    No matter how well braced, pitch is the least controlled movement
    followed by yaw. If you are very well braced, then they both might move
    together as you say, but if you're very well braced you're going to get
    fairly good shots anyway. Try shooting a 28-200 f/2.8 free hand for any
    length of time and you will be pitchin' and yawin' like crazy as your
    muscles fatique.

    Cheers,
    Alan



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    Alan Browne, Apr 24, 2005
    #20
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