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Photography 101 - Tips and Editing Techniques

Reassigning your AF Button – I think it’s Amazing!

I found this tip absolutely amazing! Perhaps I took to it so quickly because I am still a novice camera holder I still have to think for a second when I want to change the ISO or something on the camera. So obviously my camera is  not second nature in my hands… yet.  When I made the change it felt natural to me not once did I try to Auto Focus on the front of the camera after the switch. So for me I love it, plus I feel like my pictures are more in focus because of it!

When you take a picture your shutter button represents the focus, light meter and takes the picture.  That is a lot for one button! I have two kids so someone is always running in front of the camera as chaos swirls around me. I am constantly pushing the button halfway down trying to re-focus. Most of the time I end up with a blurry subject or the wrong subject in the focus.

Back-Button Auto Focus

If the distance between you and your subject stays the same. Go ahead and focus on your subject take your thumb off the button. It doesn’t matter if anyone walks in front of you your subject will remain in focus.

Once you focus on your subject you can re-compose your shot – take as many pictures as you like and your subject still stays in focus.

For more questions check out Canons article on Back-Button Auto Focus Explained. Canon also has a chart explaining how to activate this setting on different Canon EOS  models.

How to Activate back-button AF (Canon Rebel XSi)

Turn your camera dial to Creative Zone Exposure Mode (P, Av, Tv or M)

Go to Custom Function in the menu – you want to change C. Fn 10

to number 3:AE/AF, no AE lock

Give it try… If you don’t like it you can always switch back!

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4 Responses to “Reassigning your AF Button – I think it’s Amazing!”

  1. Great article.

    Back button autofocus seems to fit with with your application since it was greatly requested by sports shooters, and kids in motion always makes me feel like I’m shooting sports.

    If you are on a machine that doesn’t have a separate AFon button there is a pretty major tradeoff if you need to spot meter from somewhere other then where you are focusing or the center of the image.

    For example, say your kid is wearing all black and their face is painted white for Halloween. The center of the scene is dark but they are standing under a streetlight. Metering off of the face, clothes, or center of the scene will all give you a very bad exposure. One solution may be to meter off the sidewalk with the AE lock button * then focus on the painted face with a half press of the shutter release, then recompose and press the shutter button the rest of the way down.

    There are often times where you would like to pick your middle gray.

    Your kid is standing in the shade near the Grand Canyon. You don’t want to loose that beautiful background so you meter off the bright blue sky (* button maybe EV-1) and let your flash light your child.

    On my main body it wouldn’t matter, but whenever I jump on my 5D which doesn’t have the AFon button, I would have to reprogram myself for another way of shooting. I really fall into habits and always forget to change custom functions and reprogramming habits while action is taking place has never worked out well for me.

    Using the back button certainly has it’s place, but I’d make sure you are getting more out of it then you would having that * button an AE lock and your habits locked in accordingly.

    For the record I have my AFon button reprogrammed for AF Stop on my main body. On the 5D I just flip the AF switch on the lens.

    Posted by cyberjim | March 29, 2010, 7:52 pm
  2. My current and previous camera both have dedicated AF buttons on the back, and you know I never used them for the longest time? I could figure out what the point was at first, but then I finally got smart and realized what a help having a second AF button can be – especially when I’m out shooting wildlife and tracking focus between shots is vital. Good for you for picking up on this so much faster than I did!

    Posted by Brent Pennington | March 29, 2010, 8:47 pm
  3. Well I was just lucky to have it pointed out in the beginners photography class I took! If I hadn’t taken that class I don’t think I would have figured it out since it’s not in the manual and I haven’t come across it online, but I guess I never asked the question.

    Posted by admin | March 29, 2010, 9:16 pm
  4. @cyberjim Before I responded I wanted to play with the camera a bit to get a real feel for what you’re saying. So I switched the custom function back to its original AF settings. Then tried using the AE Lock for locking the exposure. I see your point in the trade off since I would have to actually go into custom functions every time I wanted to use the AE lock button.

    Right now I always choose Aperture Priority combined with Evaluative Exposure (Av is really where I live) and I move to Manual if I want to spot meter something. I am just starting to mess with the Manual settings as I try to understand spot metering. Metering is definitely still a bit confusing to me. If you have a picture with too much white you need to add more light so it doesn’t come out dark gives one something to think about. (I might have even said that wrong)

    As for where I am today I really do like the AF on the back with the kids running here and there. In the future I might switch it back – thanks for keeping my mind open, and for such a wonderful review on the pros and cons!

    Posted by admin | March 30, 2010, 5:01 am

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