So many of my readers are getting into employing back button focusing more since I started talking about it here on this guest post for RTS. But then I introduced metering modes in my Backlighting 101 series and now, everyone’s wondering ‘how do I tell the camera what point to meter from AND where to focus at the same time?’
Incase you’re already feeling lost, let me quickly explain the 4 things you need to understand about controlling these elements in your photography. Now, bear in mind I’m a Canon girl and these terms are as I know them for Canon models but I’m sure the concepts remain the same for other cameras.
Metering – When I say ‘tell the camera where to meter from’, what I mean is when you’re in one of the semi-manual modes like AV, you set your aperture and other settings which you’re able to control and then select a metering mode which is appropriate for your scene which will help the camera choose the right shutter speed. For example, with regards to backlit photography which we’ve been talking about recently, using ‘partial metering’ means you can make sure the camera is setting the ISO and shutter speed to properly expose the scene for the subject and not the super bright backlit background. If you’re shooting in completely manual mode, you can still set a metering mode but instead of changing any settings for you when you press the shutter halfway, the camera will just show you in the viewfinder screen exposure level indicator if you’re on target with your settings for the type of metering you’ve chosen. That part of your screen looks like this:
When the moving target is in the middle of the line {where the 0 is} then that’s the camera telling you that it thinks your settings are right for the correct exposure. So if you choose a different metering mode in manual, no setting will change, only the reading on that indicator will change. If you use a metering mode in a semi-manual mode like AV, then some of the settings will actually change when you press the shutter halfway.
Focus Points – Another thing you might be toying with now is your focus points. I always manually select my focus point by toggling the little red square in my viewfinder. More on that, using the Canon 7D as an example, here.
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Back Button Focusing – Like I said in the beginning of this post, I recently introduced my readers to BBF {back button focusing} over on Rock the Shot. No need for me to be redundant and explain that all here again. Click here to read that super plain english explanation for why you might want to use it and how to dive in.
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AE Lock – This is something new which I’ve never explained here on the blog before. The AE lock button locks your exposure settings. It freezes the camera’s settings so that if you move your camera slightly or are following a moving subject, the settings will remain the same.
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{How to focus in one area and meter from another}
So all that leads up to the big question I’m getting from readers: ‘how do I choose one spot to expose and another to focus on?’ You’ll find that since the camera uses the red focus point in your viewfinder for both the meter/exposure reading and the focusing, this can present a problem.
It’s all about the AE lock button. What you do is press the shutter halfway to meter the scene and grab the setting you want the camera to use. Then, press the AE lock button to lock the settings and you’re free to then move your camera without any of the settings changing. You’ll see the * lit up in your viewfinder screen until after you take the shot. However, should you then press the button to toggle to a different focus point, the AE settings will no longer be frozen and you’ll have to take another reading for your meter and re-lock it before proceeding. The way you can combat this problem is to use the center focus point, press the shutter halfway to take your exposure reading, press the AE lock button to freeze those settings and then, instead of moving your focus point, hold the back button to focus where you want {still using the center focus point} and then recompose and hit the shutter.
Please feel free to discuss the scenarios where you find this method useful below I’d love to know how everyone deals with this in their own ways.
{Other Ways}
Other ways to do it which have come in since this post first went live:
Change the custom setting of the shutter release to be the AE lock when the shutter button is half-pressed so you can keep your forefinger on that and your thumb on the back button ready to focus. First, choose which focus point you want to use, then point that where you want to meter and half press the shutter. Then recompose to get the focus square to your desired focus point and press the back button. Then fully press the shutter to take the image.
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