How the Canon Autofocus system works

This is a discussion on How the Canon Autofocus system works within the Articles forums, part of the Photography Tips category; I stumbled onto this and thought it was worth sharing. It's a 3-part video done by a Canon rep and he explains -- in great ...


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  1. #1
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    How the Canon Autofocus system works

    I stumbled onto this and thought it was worth sharing. It's a 3-part video done by a Canon rep and he explains -- in great detail -- how the Canon auto-focus system REALLY works.

    Ever wondered how the camera decides which auto-focus points to use when you take a shot? He explains all this and more in pretty good detail. I've been shooting for years and while I knew some of this, there was a LOT of this that I did not know (actually... the rep points out that they've had arguments... sometimes even a little heated where a top pro photographer (people who are published sports or nature photographers etc.) blame the camera for a problem when the real problem is they didn't know how the system works.

    If you own a Canon DSLR then it's definitely work checking out (it is very Canon-specific and wouldn't apply to other brands.)

    Part 1: A Look at The Canon Autofocus System | B&H Photo Online Videos | Podcasts
    Part 2: A Look at The Canon Autofocus System | B&H Photo Online Videos | Podcasts
    Part 3: A Look at The Canon Autofocus System | B&H Photo Online Videos | Podcasts

    Each segment is roughly 30 minutes (give or take about 5) so it'll take about 1-1/2 hours to watch all three.
    Tim Campbell


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    That's an excellent resource! Thank you for posting it.
    Karin


    Taking photos that please me, but if you like them too then it's a bonus!

  • #3
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    Thanks for the links Tim.

    If I could add the following ...

    My model, the 7D, comes in for a lot of criticism but you have to know how to adjust it correctly for what you are doing. It has quite a sophisticated AF system and many ways to adjust it. It also allows you to fine tune the focus for each lens. Unlike other cameras, it may not perform well straight out of the box. Anyway, I'm happy with mine, and here's a link for others who may be struggling with the 7D.

    Here's another link you might find useful regarding the age old comment This Lens is soft.

    Regards
    Graydon
    Graydon

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  • #4
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    That's a good point Graydon. They do discuss the 7D focus system and explain the difference between a primary focus point vs. a "focus assist" point and also talk about the real size of the focus point vs. the size depicted in the viewfinder and that the focus-assist points essentially allow you to "extend" the area of the focus point if you turn them on.

    They also cover the lens micro adjustments on the cameras that support the feature (50D, 7D, 5D, etc.)

    I can imagine it's a bit of a frustration for the camera maker (in this case, Canon) because they take input from the top-shooters and design their new models based on the input they get. A lot of the capability comes from what they've been asked to provide and they have to rationalize how to implement it. In the end, they make the top shooters happy. BUT... if you get people who don't know why they designed the system to work a particular way and how the system worked before they were asked to modify it, then you get people who just expect it to work a miracle and then accuse the manufacturer because they ended up with a pile of soft images. And the tragic part is that, had those people invested the time to learn how the system works, the whole mess could have been avoided.

    Like I said above. I "thought" I knew how the AF system worked on my Canons. I discovered I knew a little... but there was a quite a lot more that I didn't know.

    I even learned that some of the stuff I've read in books about how the various AF modes work turned out to be wrong.
    Tim Campbell

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    Hi Tim,

    Found some time to review these this evening and yes they were extremely useful. It doesn't cover the 7D, but some things mention in the 1D Mk3 I recognise and have. Also, much of the detail is generic it should be of interest to most people.

    Thanks again for the links.

    Graydon
    Graydon

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    Canon 7D | Sigma 10-20mm | Canon 24-105mm L | Canon 70-300mm L

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