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7D focusing

pixelparablepixelparable Registered Users Posts: 27 Big grins
edited April 6, 2010 in Technique
Hello All :)

i do not remember throwing away many shots with my 20D when shooting sports...but it seems half or more of my shots with the 7D are blurry(slightly)...this shot was something round 2000 shutter or more..100 or 200 iso...f/2.8...on a monopod...i am using the 7D plus battery grip and 70-200 f/2.8...the same setup i was using with my 20D....Also i am using zone metering(center zone) and AI Servo.....and also when i have it in this setup I am not getting 8fps...?? any and all HELP is greatly appreciated...Thanks in advance

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    MalteMalte Registered Users Posts: 1,181 Major grins
    edited April 2, 2010
    I know that "Fast continous" is a separate setting from "Continous".

    Malte
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    pixelparablepixelparable Registered Users Posts: 27 Big grins
    edited April 2, 2010
    yeah i have it set to fast continous or better named continous H :)
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    ziggy53ziggy53 Super Moderators Posts: 23,887 moderator
    edited April 2, 2010
    There are many factors that affect continuous mode shooting rate. The biggest slowdown occurs using High-ISO noise reduction, so turn that feature off for much faster continuous shooting rate.

    Slow shutter speeds will slow down the camera as will small aperture settings. The Canon 7D is also prone to slowing down in indoor low-light levels because the metering system is now tied to the AF system.

    The AF acquisition speed also affects continuous shooting speeds so some lenses will slow down overall throughput.

    Shooting RAW files will fill up the shot buffer faster than shooting JPGs, and the RAW files take longer to transfer into the CF card.

    It also appears that using the AA battery sled in the vertical grip will reduce continuous shooting speed.

    Relating to your out-of-focus problems, what method and technique do you use for AI-Servo? (What specific steps do you take to make the shot?)

    AF point setup?

    What lens? (Which 70-200mm?)

    If an IS lens how is the IS set?
    ziggy53
    Moderator of the Cameras and Accessories forums
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    gecko0gecko0 Registered Users Posts: 383 Major grins
    edited April 2, 2010
    One thing I've learned to look for when I miss a shot is if anything is in focus...if it is, that tells me the AI Servo grabbed onto something else for a split second. From what I've read, if nothing is in focus (such as your example pic), then it's most likely camera shake. Of course, at 1/2000, that seams somewhat unlikely...but still possible.

    Is the image posted cropped?
    Canon 7D and some stuff that sticks on the end of it.
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    pathfinderpathfinder Super Moderators Posts: 14,698 moderator
    edited April 2, 2010
    The sharpest area seems to the #18's left foot. There is considerable chromatic aberration - green fringing - along her right shoulder, I agree that motion seems to be part of the problem. The individual along the right side of the image, in the background, has a doubled margin, which is not simply out of focus.

    The image measures 545 pixels wide by 720 pixels tall, so it definitely has been cropped as the ratio is not 1.5, but more like 1.3. I wonder what portion of the original full size image this picture represents.

    Exif from the image ISO 200, f2.8 1/4000th, 200mm

    I just never seem to get perfectly sharp images at f2.8 unless the subject is stationary - I am just not that good.

    Have you tried micro adjusting your lens to optimize the focusing with your lens? I found that can make a significant improvement with some lenses. My Sigma 150-500 was much better after I adjusted its AF micro focus point.
    Pathfinder - www.pathfinder.smugmug.com

    Moderator of the Technique Forum and Finishing School on Dgrin
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    pixelparablepixelparable Registered Users Posts: 27 Big grins
    edited April 3, 2010
    high iso noise reduction is off....

    i do not know what "micro adjusting" is ?? How do you do it the right way ??
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    pixelparablepixelparable Registered Users Posts: 27 Big grins
    edited April 3, 2010
    pixelparable wrote:
    high iso noise reduction is off....

    i do not know what "micro adjusting" is ?? How do you do it the right way ??



    the lens is a non IS lens....it is the 70-200 f/2.8 II sigma APO EX DG
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    pixelparablepixelparable Registered Users Posts: 27 Big grins
    edited April 3, 2010
    here is the original image....it appears to be somewhat in focus....but as you crop it gets way blurry.....i have another photo from this day that i cropped alot as well and it is very crisp and clear under the same crop....and many are like this :(
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    ziggy53ziggy53 Super Moderators Posts: 23,887 moderator
    edited April 3, 2010
    AI Servo is a mode of AF which tries to calculate the proper focus for a future point in time using AF sampling and then calculating the changing AF rate against time. It is otherwise called "predictive" autofocus.

    Proper AI Servo technique is to track the action with the shutter button half depressed, keeping the intended subject in the area of focus (determined by your AF point selection) and the predictive algorithm can take up to 1 second of sampling. Then, when you see the camera maintaining focus, you press the shutter button through, preferably in a short burst of continuous shooting. The Canon 7D is reportedly returning sharp images in good light from the high 60th percentiles into the low 70th percentiles within a series.

    I prefer using single focus point AF selection, and the center dot is most accurate, and then an aperture selection which allows sufficient DOF for the AF field I wish to cover. Wide open at f2.8 the DOF is very thin and the success rate will drop considerably as a result. When you do see success it is usually pretty dramatic however as the foreground and background melt away, isolating the action.

    If the action is unpredictable you might try instantaneous (One Shot) AF instead of AI Servo. The camera requires less lead time for AF acquisition, but it's less suited for sequence shooting.
    ziggy53
    Moderator of the Cameras and Accessories forums
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    pathfinderpathfinder Super Moderators Posts: 14,698 moderator
    edited April 3, 2010
    pixelparable wrote:
    high iso noise reduction is off....

    i do not know what "micro adjusting" is ?? How do you do it the right way ??

    AF micro-adjustment is Custom function III-5 and described on page 211 of the manual for the 7D.

    A how to description is found here This is a long thread and gets even better towards the end, so don't just read the first page and quit. It is a worthwhile read for all owners of 50D and 7D cameras, as well as the 1 series cameras.

    I suspect you could make your microadjustments and evaluate them right on the camera with Live View also but have not actually done it that way. The easiest way would be tethered viewing and adjusting.

    I would suggest shooting some frames at f4 and f 5.6 as well, and see if they aren't a lot sharper. The optics work better 2 stops down, and the DOF is substantially larger. You will still have the background out of focus with the 200mm lens.
    Pathfinder - www.pathfinder.smugmug.com

    Moderator of the Technique Forum and Finishing School on Dgrin
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    pixelparablepixelparable Registered Users Posts: 27 Big grins
    edited April 6, 2010
    thanks pathfinder and all others :)
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