Canon 70D - AE Lock
Jan 18, 2015 16:49:26 #
I recently upgraded from a Canon T4i to the Canon 70D. I am busily learning all the new functionality.
So here's a question for someone out there who already knows the intricacies of this wonderful camera.
In the manual, p. 170, it seems to say that when you are set for Evaluative Metering, and you press the AE Lock, then the exposure is locked based on the lighting at the chosen AF point.
SO, in the attached picture, the exposure would be locked based on the left side of the picture. Is that correct? If so, that is really handy.
So here's a question for someone out there who already knows the intricacies of this wonderful camera.
In the manual, p. 170, it seems to say that when you are set for Evaluative Metering, and you press the AE Lock, then the exposure is locked based on the lighting at the chosen AF point.
SO, in the attached picture, the exposure would be locked based on the left side of the picture. Is that correct? If so, that is really handy.
Left Zone AF
Jan 19, 2015 22:03:34 #
amfoto1
Loc: San Jose, Calif. USA
First, I don't have 70D... But I do have experience with a lot of other Canon models and I believe their metering systems are the same or very similar (7D, for example).
Put aside the way you have set up AF and AE-Lock for the moment.
Evaluative Metering in all Canon always puts "extra emphasis" on the active AF point. The rest of the image area is considered when calculating exposure, but the metering is biased pretty heavily toward that active AF point and the area immediately around it.
Now, AE-Lock simply does what it says... It locks the exposure at whatever the camera is currently reading with it's metering system (doesn't matter which metering mode or how AF is set up, although it can be different with each of those).
AE-Lock needs to be used sparingly and deliberately. A good example is if you are photographing a person in front of a beautiful sunset, want to be sure to expose their face correctly. So, step closer so their face is most of the image area, press AE-Lock, then step back, re-frame the image and take the shot. The sunset in the background will be over-exposed, of course, but the person's face should be properly exposed.
A lot of the time, shooting in "typical" situations, you really don't want exposure locked. You want it to be able to respond to changing factors in the image. So be a little cautious how you use it.
Besides Evaluative Metering, which I described above, there also are Center Weighted (also puts some emphasis, but it is not as much or as targeted as Evaluative). Partial Metering and Spot Metering are both more narrowly defined and targeted than Evaluative. Spot meters almost exclusively the area within the circle seen in the viewfinder. Partial expands upon that a bit.
Center Weighted, Partial and Spot are not linked to the auto focus points at all...in your camera (...in a few models it's possible to link Spot to the active AF point). Only Evaluative is.
The AF Point has to be "active", though. It has to be locked onto and focusing on something. Just "selecting" any given point or group of points with the 70D's AF system isn't enough... Evaluative will do the bulk of it's metering based upon one or two, sometimes 3 or 4 of those points, though, once they are actively focusing on a subject.
I've used a pair of 7D for over five years now. The AF system in your camera is based upon and very similar to the 7D's.
I've found that the "fancy" or more automated modes need to be used sparingly and in the right situations. I almost never use All Points. Zone Focus can work well in certain situations, but is sort of a scaled down version of Zone Focus.
Single Point remains the most accurate, because it leaves you in charge of where the camera focuses, rather than letting it decide for you. It's what I use most of the time and it works well in conjunction with Evaluative Metering, too. (7D have two more modes that your camera doesn't have: Expansion Points and Spot Focus. I use these more than I use Zone.... Especially Spot Focus, which is a high precision AF using a smaller point than usual.)
Put aside the way you have set up AF and AE-Lock for the moment.
Evaluative Metering in all Canon always puts "extra emphasis" on the active AF point. The rest of the image area is considered when calculating exposure, but the metering is biased pretty heavily toward that active AF point and the area immediately around it.
Now, AE-Lock simply does what it says... It locks the exposure at whatever the camera is currently reading with it's metering system (doesn't matter which metering mode or how AF is set up, although it can be different with each of those).
AE-Lock needs to be used sparingly and deliberately. A good example is if you are photographing a person in front of a beautiful sunset, want to be sure to expose their face correctly. So, step closer so their face is most of the image area, press AE-Lock, then step back, re-frame the image and take the shot. The sunset in the background will be over-exposed, of course, but the person's face should be properly exposed.
A lot of the time, shooting in "typical" situations, you really don't want exposure locked. You want it to be able to respond to changing factors in the image. So be a little cautious how you use it.
Besides Evaluative Metering, which I described above, there also are Center Weighted (also puts some emphasis, but it is not as much or as targeted as Evaluative). Partial Metering and Spot Metering are both more narrowly defined and targeted than Evaluative. Spot meters almost exclusively the area within the circle seen in the viewfinder. Partial expands upon that a bit.
Center Weighted, Partial and Spot are not linked to the auto focus points at all...in your camera (...in a few models it's possible to link Spot to the active AF point). Only Evaluative is.
The AF Point has to be "active", though. It has to be locked onto and focusing on something. Just "selecting" any given point or group of points with the 70D's AF system isn't enough... Evaluative will do the bulk of it's metering based upon one or two, sometimes 3 or 4 of those points, though, once they are actively focusing on a subject.
I've used a pair of 7D for over five years now. The AF system in your camera is based upon and very similar to the 7D's.
I've found that the "fancy" or more automated modes need to be used sparingly and in the right situations. I almost never use All Points. Zone Focus can work well in certain situations, but is sort of a scaled down version of Zone Focus.
Single Point remains the most accurate, because it leaves you in charge of where the camera focuses, rather than letting it decide for you. It's what I use most of the time and it works well in conjunction with Evaluative Metering, too. (7D have two more modes that your camera doesn't have: Expansion Points and Spot Focus. I use these more than I use Zone.... Especially Spot Focus, which is a high precision AF using a smaller point than usual.)
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