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Thread: Canon 17-40mm Secrets Revealed!

  1. #1

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    Canon 17-40mm Secrets Revealed!

    I have been learning about my new Canon 17-40mm that I use on a Canon EOS D5 Mark ll. This lens is sharp from 17mm through 40mm but sharper using f/7.1 to f/14 in my experience. An ISO of 200 works very well on a sunny day to help keep shutter speeds up at smaller apertures. However, at the wide end the camera sometimes fails to find a good focus and the result is a "soft" image. Some people focus the lens at 35-40mm, lock the focus, zoom to 17-24mm or so, recompose and shoot. This seems to work. Also, study the focus points carefully through the eyepiece. More illuminated focus points seem to bring forth sharper images.

    Attached photo of palm is 17mm, ISO: 200, f/11 & 1/160s. Canon 17-40mm Secrets Revealed!

    Sign is 36mm, ISO: 200, f7.1, 1/164sCanon 17-40mm Secrets Revealed!

  2. #2
    Wayland's Avatar
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    Wayland ( aka. Gary Waidson )

    Re: Canon 17-40mm Secrets Revealed!

    I've never noticed a focussing problem on my 5D but I'm usually working around f11.

    I'll have to check it out at some point when I'm out next.

  3. #3
    MilT0s's Avatar
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    Miltos

    Re: Canon 17-40mm Secrets Revealed!

    Hi Ed.

    Some notes on focusing and lens performance I have found on the web:

    - All lens are sharper at about two stops from their larger aperture thus at f8 for your lens. This is more prominent for cheaper lens. It's one reason to choose a fast lens (prime?) even if you don't need a swallow DoF.

    - The autofocus works better not at "more illuminated focus points" but at high contrast points (often the one brings the other)

    - Try to only use the more sensitive central focus point under difficult conditions.

    - Keep in mind that the focus and recompose method often doesn't work with shallow DoF if the focus plane is changed during the lens movement.

    - I always have the rule on shutter speed on my mind while shooting: The speed should be at least (actually faster than) 1/focal length you shoot not accounting for image stabilization (which your lens don't have).

    - Your camera performs very very well at higher ISO and the benefits of doing so is often greater than the quality reduction.

    - I am planning to buy this beauty (EF 17-40) myself!

  4. #4

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    Re: Canon 17-40mm Secrets Revealed!

    Excellent points. I have seen reviews by a small percentage who were disappointed in this lens. The actual issue may well have been a failure to recognize that a photographer must acquire experience with a lens to discover its strengths and weaknesses. This, in addition to any particular camera's strengths and weaknesses. Not to mention the photographer's skill and knowledge. In sum, for a period of time with new equipment, every photograph should be an experiment in photography.

    Canon 17-40mm Secrets Revealed!

  5. #5

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    Re: Canon 17-40mm Secrets Revealed!

    The trouble with many wide angles is that one forgets to look at what the camera is focusing on. All to easy to allow sharp focus on nearest object rather than the subject, or if selecting a point letting the camera focus on the sky. SLR's are not point and shoot.

  6. #6

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    Re: Canon 17-40mm Secrets Revealed!

    17-40mm as a closeup lens...

    Canon 17-40mm Secrets Revealed!

    ISO: 200, f/7.1, 1/100s, 37mm

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