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Thread: test shots

  1. #1
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    Default test shots

    In another thread a comment was made that I was unaware of, you can in certain situations shoot in auto focus with a lens and tc in excess of f8.
    1st shot by R MAURINS, on Flickr
    This is deliberately shot in poor conditions, through a window in poor light, no photo shop at all.

    x2 tc fitted by R MAURINS, on Flickr
    Taken from the same position, just to test that auto focussing does take place.
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  2. #2

    Default Re: test shots

    It does at least show one other thing ,either your focussing is out of sync using the t.c or if the statues eye was the target you have a serious back focus issue .
    Sometimes being able to actually do something doesn't achieve the desired results with the finished article .i have found that sometimes using a t.c to get that much closer also aggravates the focus ,if your focus square see's more than 50% of background in its area then it will assume the background is the target ,so as I said it's either back focussing or user error .

    My area figure above is also hypothetical as I have no idea of canons actual focus algorithm .suffice to say it's sometimes better to crop in on a sharp image rather than attempt to improve the focal length with a t.c .with indifferent results
    Last edited by the black fox; 17-04-2017 at 07:10.

  3. #3
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    Default Re: test shots

    If I can get 800mm up to the top of a mountain without another hernia Jeff I'll be happy to crop to my hearts content later after sorting out the finer arts of focussing and photo shopping. This was purely an exercise to see if you can autofocus at f11 at 800mm, will go sit on a mountain and see just how practical this actually is later.
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  4. #4
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    Default Re: test shots

    Sparrow test shot by R MAURINS, on Flickr
    This is straight off the camera, zero editing or cropping, just to see how it works, auto focus can be slow and I find manually focussing and then finishing the shot in auto, helps stop the lens "hunting". This won't work in every situation, but when I'm in the hills and glens stalking Red Deer, this could just help, giving me 800mm hand held that doesn't need a Sherpa to get it up there.
    Last edited by tigerburnie; 20-04-2017 at 15:23.
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  5. #5

    Default Re: test shots

    I note that the sparrow picture says you were using live view. I suspect that since the camera is using is using contrast detection rather than the normal phase detection sensors it ignores the f8 limit and will focus as long as it can find an edge with sufficient contrast.

    I assume it was Canon extender you used? Unlike Canons own TCs 3rd ones frequently don't seem to disable the AF system - probably because they don't report the effective aperture.
    Nigel

    You may know me from Another Place....

    The new ElSid Photogallery...

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  6. #6
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    Default Re: test shots

    I don't know how it does it Nigel, but it does work after a fashion and yes it's a Canon mk ii. I will bear in mind what you say about edge contrast.
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  7. #7
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    Default Re: test shots

    Herring Gull by R MAURINS, on Flickr
    Very pleased the way this works, not perfect as it is rather long for hand holding, but it works. This straight off the camera.
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