Canon 20d focusing issues

Discussion in 'Canon' started by Todd.J.Olson, Sep 27, 2005.

  1. Todd.J.Olson

    Todd.J.Olson Guest

    I just posted this on rec.digital, but this is probably a more
    appropriate place for it.

    Hello,

    Let me start off by saying I'm very new to photography. I bought the
    20d to take to Europe in hopes of getting some large prints made. It's
    my first D-SLR. Ever since I bought this camera I've had trouble
    getting photos to come out well. I don't think I've really ever gotten
    a photo in a 'mode' setting to come out clear. I always have soft
    edges and overexposure. I tend to shoot mainly in manual mode, but
    sometimes still have problems. My biggest issue is getting focused
    clear images. If I'm just taking photos of friends around town, I
    typically set the camera around 1/100th (in the time-priority mode) of
    a second to keep from blurring the shot with my unstead hands.
    Sometimes this works, sometimes it doesn't. Recently I went to a
    wedding and did this same thing, and almost every photo I took came out
    blurry. Now I have taken some crisp shots, but they are almost always
    from far away on nice sunny days. I like to go hiking and take the
    camera, but the dark woods don't always make the greatest shots.

    Here are two photos I took this morning on my couch. The data from the
    shots follows. The first shot was in AE mode set. The second was in
    fully automatic. Notice how soft the edges are on the fully automatic
    shot. This is what keeps happening every time I take a photo. Does
    anyone know what is going on, or care to suggest how to resolve this?

    http://filebox.vt.edu/users/tolson/photos/IMG_2130.JPG (forgot to
    turn down ISO from last night, a little grainy)

    http://filebox.vt.edu/users/tolson/photos/IMG_2132.JPG

    Here's a shot from the wedding that came terrible just to show you what
    I'm so confused about.

    http://filebox.vt.edu/users/tolson/photos/IMG_2104.JPG

    Thanks for any insight, -Todd

    I'm using a canon 28-105, seen here: (not L-glass)
    http://consumer.usa.canon.com/ir/controller?act=ModelDetailAct&fcateg...

    wedding photo
    ------------------------------
    File Name
    IMG_2104.CR2
    Camera Model
    Canon EOS 20D
    Shooting Date/Time
    9/17/2005 3:27:06 PM
    Shooting Mode
    Manual Exposure
    Tv( Shutter Speed )
    1/80
    Av( Aperture Value )
    16.0
    Metering Mode
    Evaluative Metering
    ISO Speed
    400
    Lens
    28.0 - 105.0 mm
    Focal Length
    35.0 mm
    Image Size
    3504x2336
    Image Quality
    RAW
    Flash
    Off
    White Balance Mode
    Auto
    AF Mode
    One-Shot AF
    Parameters Settings
    Contrast Mid. High
    Sharpness Mid. High
    Color saturation Mid. High
    Color tone 0
    Color Space
    sRGB
    Noise Reduction
    Off
    File Size
    7912 KB

    manual
    ---------------------------------------
    File Name
    IMG_2130.CR2
    Camera Model
    Canon EOS 20D
    Shooting Date/Time
    9/27/2005 1:35:42 PM
    Shooting Mode
    Shutter-Priority AE
    Tv( Shutter Speed )
    1/100
    Av( Aperture Value )
    4.0
    Metering Mode
    Evaluative Metering
    Exposure Compensation
    0
    ISO Speed
    800
    Lens
    28.0 - 105.0 mm
    Focal Length
    65.0 mm
    Image Size
    3504x2336
    Image Quality
    RAW
    Flash
    Off
    White Balance Mode
    Auto
    AF Mode
    Manual Focus
    Parameters Settings
    Contrast Mid. High
    Sharpness Mid. High
    Color saturation Mid. High
    Color tone 0
    Color Space
    sRGB
    Noise Reduction
    Off
    File Size
    7428 KB

    fully automatic
    --------------------------------------
    File Name
    IMG_2132.JPG
    Camera Model
    Canon EOS 20D
    Shooting Date/Time
    9/27/2005 1:37:55 PM
    Shooting Mode
    Auto
    Tv( Shutter Speed )
    1/60
    Av( Aperture Value )
    4.0
    Metering Mode
    Evaluative Metering
    Exposure Compensation
    0
    ISO Speed
    400
    Lens
    28.0 - 105.0 mm
    Focal Length
    82.0 mm
    Image Size
    2544x1696
    Image Quality
    Fine
    Flash
    On
    Flash Type
    Built-In Flash
    Flash Exposure Compensation
    0
    Red-eye Reduction
    Off
    Shutter curtain sync
    1st-curtain sync
    White Balance Mode
    Auto
    AF Mode
    AI Focus AF
    Parameters Settings
    Contrast Mid. High
    Sharpness Mid. High
    Color saturation Mid. High
    Color tone 0
    Color Space
    sRGB
    Noise Reduction
    Off
    File Size
    1641 KB
     
    Todd.J.Olson, Sep 27, 2005
    #1
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  2. 20D's are unique in their ability to fool people into thinking they'll
    get "good" photos all the time... You won't!

    First things first.
    The Matrix metering system judges exposure based on the brightest
    object. It gets that right and expects you to be able to fix the grey
    mess with Photoshop afterwards.

    The Second thing is matrix focus. This doozey randomly chooses one of
    the live points that momentarily flash red when you partly depress the
    shutter button based on a method similar to Russian Roulette. You
    probably will never get a properly focused picture with this system and
    to make it worse, this is the "default" method of focusing.

    Thirdly, These cameras have extremely shallow distance between the back
    of the lens and the sensor. This distance is known as "back Focus". If
    it's out by as little as 0.01 of a millimeter, the camera won't focus
    properly at close distance. I have no statistics but I'd guess at about
    10% of all 20D manufactured, have something less than exact back focus
    settings. 300D and 350D will also suffer this problem but you won't hear
    as much about it because of the cost of wide open glass.

    Canon's answer to this crap is to claim the cameras come with a f3.5
    lens and the focus is correct if it is anywhere within the depth of
    field of a "Kit lens". Some people say they couldn't get it fixed until
    they presented the camera with a f1.4, 50mm lens. I guess a kiosk hiring
    them out beside the warranty door of Canon might become a profitable
    sideline!

    So... For the average newbie to unpack the camera and start shooting and
    get bright, well focused pictures, first time up is like winning the
    lottery... Some can and most can't.

    Now is the time to move into the previously black area of *INSTRUCTION
    MANUAL* and alter the custom functions so you get 'single point' focus.
    What you point at will then be the focus point.

    Next, alter the metering to centre weighted, instead of matrix metering.
    What's in the middle of the picture will then be correctly exposed.

    If you don't have Photoshop and you don't like the rather flat looking
    pictures you get from a "Pictbridge" enabled printer, you might also
    crank up the contrast settings but be aware this will almost certainly
    blow away highlights.

    End of lesson 1.:)
     
    Pix on Canvas, Sep 28, 2005
    #2
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  3. Turn off all the focus points except for one.
     
    Randall Ainsworth, Sep 28, 2005
    #3
  4. Todd.J.Olson

    Skip M Guest

    First, I'm not sure what the issues are, they seem to me to be consistent,
    in the case of the notebook, with depth of field, the near corner is too
    close to be in focus, the far corner, too far to be in focus, if you were
    using a large aperture.
    The wedding image, I dunno. I'm seeing subject movement, camera movement,
    and general lack of sharpness. 1/80 sec is too slow for good capture of
    moving subjects, and sometimes difficult to hand hold at that slow of a
    speed, too.
    That being said, we sold our 28-105 f3.5-4.5 because its weaknesses were
    made obvious with the 20D in a way that it never was with film or my wife's
    10D. If that is the lens you're using, it could be the issue. If you are
    using the 28-105 f4.5-5.6, then that definitely is the problem, that lens
    has a horrid reputation.
     
    Skip M, Sep 28, 2005
    #4
  5. Todd.J.Olson

    Mike Warren Guest

    I have only looked at the wedding shot and this is what I see:

    -The pattern on the waist on the brides dress is reasonably
    in focus.

    -The grooms head is moving forward causing slight motion blur.

    -The brides hand and arm are moving causing motion blur.

    -The brides maid is outside the DOF and therefore out of focus.

    -The camera is moving in a rotary direction with an axis just below
    the centre of the picture.

    -The background is blurred partly due to DOF and partly due to
    the camera movement.

    What I don't understand is why the DOF is so small when the
    lens is set to 35mm and F16. There's something odd there.
    Perhaps diffraction is adding to the problems.

    At 1/80th of a second shutter speed you need to really hold the
    camera still. The direction of the camera movement suggests that
    you may have pushed the shutter release instead of gently
    squeezing it.

    Has this picture been reduced or cropped?

    -Mike
     
    Mike Warren, Sep 28, 2005
    #5
  6. Hi Todd,

    I hear were you're coming from - I used to suffer much the same fate. In
    fact, I used to be the worlds worst photographer, but 6 months down the
    track I reckon I'm only about 4th worst now - so things are getting better!

    I can't speak with the experience of many around here, but what I've
    discovered is that the issue I was having wasn't just 1 thing - it was a
    combination of things.

    First up, I took delivery of my first "L" series lens (a 24-70 F2.8L USM) -
    the same day I put my kit lens for sale on an online auction site - I'll be
    quite happy to never see it again. Many will say that you can take a good
    shot with cheap glass - probably quite true, but I think the people who can
    are better photographers than I'll ever be. If you're going to be blowing
    things up then all the more reason to get some quality glass (I appreciate
    that you weren't using the kit lens - but not "L" glass either).

    Second up, I had a problem with Camera shake - I just didn't know it at the
    time. I always thought I had pretty steady hands - but even with L series
    glass on a borrowed 70-200 F2.8L USM (non IS) I had a significant problem
    unless I was outside on a bright day, or on a tripod. I tried to follow the
    Reciprocal shutter speed rule (ie at 200mm shoot no slower than 1/200th sec
    etc - but even that just didn't cut the mustad. Until I get my IS lens I'm
    going to stick to cranking up the ISO so that I'm hand holding somewhere
    above 1/500th with the 70-200 lens (where I'm getting better results). If I
    were to get a good shot inside (at, say, a wedding) hand held, it would
    probably just be good luck - especially if they were moving).

    Third up (pure speculation here) - I'm hoping that an IS lens is going to
    make a big difference. It just occured to me that when Canon talk about it
    making up to 3 stops of difference, that's actually an EIGHT fold difference
    (each stop is a doubling or halving) - so 1/200 drops to 1/25 - hopefully
    opening up many more F-Stop / ISO / Shutter speed options.

    Forth, nearly all images benefit from sharpening in photoshop.

    For me it was summed up nicly the other day when I took some photos of my
    daughters - previous attempts were only ever "OK" at best - but with some
    borrowed "L" glass - camera mounted on a tripod - good lighting - and a good
    sharpen in photoshop I ended up with some 10 * 15" prints that were sharp as
    a tack (I was actually quite impressed with myself).

    These days I'm getting more into longer lenses for bird photography. I
    purchased some books by Arther Miller that were suggested by someone here -
    and guess what - he recommends a $700 Gitzo tripod - a $565 Wimberley head -
    L series Glass - IS when available - remote shutter releases - and
    additionally, lots of good techniques. Looking back at where I was with very
    little knowledge, and a few other factors working against me it really
    wasn't a surprise that I was getting the poor results that I was. I'm
    wondering if you're in the same situation?

    Cheers,

    CC
     
    Cockpit Colin, Sep 28, 2005
    #6
  7. Cockpit Colin wrote:
    []
    I can't comment on the Canon lens, but with the Panasonic FZ5 and its
    Leica image-stabilised lens, a factor of around ten seems to be achieved -
    it makes tremendous difference. With your 200mm lens (300mm equivalent),
    you could perhaps be looking at 1/30s - of course it's better to spread
    the gain between aperture and shutter speed as the taking conditions
    dictate.

    David
     
    David J Taylor, Sep 28, 2005
    #7
  8. Part of the problem may be shutter speed, I notice one shot was 1/100 with a
    82mm focal length.

    I would suggest for handheald you should use 1/1.6/F, so 1/1.6/85=1/136 so
    perhaps 1/150 would be good. If you want it really sharp or have shakky
    hands 1/300.

    If you have al the focus points on you don't know where it is focussing for
    sure try using just one point.

    Don't forget the camera output will require sharpening unlike a
    point-and-shoot.
     
    Lester Wareham, Sep 30, 2005
    #8
  9. If you know what you do, any working camera will give you
    that almost all of the time, if you have no idea, well, it's
    a gamble.
    Funny how wrong you are, it happily overexposures the sky or
    lamps in the image frame to get the rest right (ok, you so
    should probably use a light bouncer or flash). Which, if you
    were really right, wouldn't ever happen. I rather find the 20D
    to blow highlights at times a bit to agreessively.

    And it's 'evaluative', not 'Matrix'. 'Matrix' is the Nikon
    term. Are you thinking of some Nikon camera, mayhaps?

    In other words, you have no idea how it works, or have prejudices
    or simply are incompatible with the camera and project your
    problem onto the 20D, which obviously cannot contradict you.

    It chooses *all* the life points that flash, that's why they
    flash: the AF believes they are in focus. RTFM.

    How it chooses which points to focus is of course more complicated,
    I find it works OK, though pre-choosing one sensor can be a good
    idea: It is faster, for example, and harder to fool --- if you
    know what you do.
    Nope. That would be a rangefinder camera, or maybe an EVF camera,
    where the lens can be mere millimeters away from the sensor/film.

    Due to the necessary, design-immanent mirror SLR cameras do have
    a lot of space between lens and sensor. This causes wide angle
    lenses needing a comparatively complicated and large retrofocus
    design.
    Nope, that is if the camera (or the photographer manually, using
    a proper focussing screen) focuses, but the focus point in the
    image is behind what you focussed on. (compare "front focus")
    Canon claims the acceptable AF accuracy for the 20D is +/-0.02mm
    on the sensor site, if I understood
    http://www.cps.canon-europe.com/kb/detail.jsp?faqId=1110
    correctly, so 0.01mm is not a problem.

    Actually, important is only if the distance lens-focus screen
    and lens-sensor is (near) identical ...
    Nice guessing, how do you derive that number? Anything more
    scientific than rolling dice? Or is that the same wisdom and sage
    advice you pulled in the "extremely shallow distance between the
    back of the lens and the sensor"?

    Yes, there have been a few problems with incorrect focussing,
    as far as I hear-tell. But even if 0.1% (one in 1000) of the 20D
    have a problem, that is a high absolute number which is all some
    people see, without relating it to the much much higher number
    of sales ...
    Care to provide a Canon URL or letter claiming that?

    Truth is, the 20D's AF is to focus within the depth-of-focus of
    the open lens, see:
    http://www.cps.canon-europe.com/kb/detail.jsp?faqId=1002

    With a f/3.5 lens on the camera this is of course within the
    depth-of-focus of the f/3.5 lens ...

    Are you sure that the error is not within their 50mm f/1.4
    lens, if it's only demonstable with the lens?
    If you are a newbie, go learn your tools first, and read the
    instruction manual. Or buy a Point&Shoot with just a Power
    and a Shutter button.

    Or do you propose to use Photoshop without ever learning it
    nor reading the instruction manual?
    This is not a custom function, but a dedicated button, though
    you can alter the way to select the active focus point via a
    custom function. You sure you ever used a 20D?
    Which is really helpful if you want all your subjects in the
    center of the image. Really interesting pictures, you know?
    The 20D has a P1 preset for those wanting a more P&S-like look.

    Have you actually tried if highlights are blown, or is that
    just another random spouting? Or is that because you use
    center-weighted instead of evaluative metering?

    -Wolfgang
     
    Wolfgang Weisselberg, Oct 12, 2005
    #9
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