Locking exposure on the 7D

I might have asked something along this line before, but I'm having a problem trying to figure out how to lock exposure with any of the movable focus points. It appears that wherever I chose the focus point the camera exposes at the center of the frame. I want to be able to lock focus and exposure at any ONE of the 19 chosen focus points. Can this camera do that? With every dSLR that I have owned in the past I can focus and expose at any given focus point. Could someone assist me with this please. Thanks guys.

Cheers

Wayne

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"Every day the world turns over on someone who was just sitting on top of it."

What metering mode are you using?

Canon's evaluative metering, weights the exposure to the active auto focus point.

I seem to remember that you were shooting in Center weighted avg mode.  Correct me if I am wrong.  But in that mode, you are correct, it still meters at the center.

On the other hand, if you switch to evaluative mode, the metering STRONGLY follows the selected AF point.  I actually like this method better than spot focus linked to the selected AF point, because you are less likely to get completely blown out highlights.  But, the exposure still pretty much follows the selected AF point.  I did some tests with mine and was surpirised at how strongly it followed the selected point and how well it all worked.  Evaluative mode is the key.

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kind regards
Dale

Thank you for responding. I just got off the phone with a Canon rep and he mentions that the only Canon camera that will allow spot metering at any given focus point is the 1DX. All other Canon models will only spot meter at the center point within the frame no matter what focus point I choose. If I chose evaluative metering, the camera will take a valued reading of the entire frame no matter what focus point I choose. So if I choose spot, center weighted of evaluative, the metering starts from the center of the frame. I don't know why they do not allow for spot metering at any given focus point other than their expensive 1DX, but I do know that with all the Nikon dSLR cameras that I have owned, they will allow that. I am disappointed, but what can I do.

Cheers

Wayne

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"Every day the world turns over on someone who was just sitting on top of it."

That is encouraging Dale. I just got off the phone with a Canon rep and he mentioned that even if I had the camera set to evaluative, the exposure is an evaluated value taken across the entire frame starting out from the center of the frame no matter what I choose, either spot focusing or an selected cluster.

Dale, which focus point did you select, was it the center focus point, or was it one of the outer points?

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"Every day the world turns over on someone who was just sitting on top of it."

Hate to dispute what the Canon Rep told you but:

Evaluative: Metering is directly linked to, and concentrated on, the area around the active AF point, whether you’ve focused on something in the center or off-center. Light values measured at the active AF point are compared with light values measured from the metering segments across the remaining areas of the scene, and the camera's metering system attempts to provide an accurate exposure based on that comparison. This metering pattern is often effective when photographing people, but may not be quite as effective when photographing snowy landscapes depending on other elements in the scene. Note that because Evaluative Metering is linked to active AF points, focusing on a different subject may result in a very different exposure — even within the same scene.

http://www.learn.usa.canon.com/resources/articles/2011/qt_photograph_snow_article.shtml

Let me see if I have this correct. If I select a focus point dead center of the frame, the camera will concentrate the exposure value around that point, but take into consideration the rest of the frame. Now if I was to select the farthest focus point to the right, the camera will concentrate the exposure around that farthest selected point and then evaluate the rest of the frame outward from that point. If that be the case then, it will work very well for outdoor portraits. So if I select a focus point at the subjects face without having to recompose the picture, the exposure will be concentrated on my subjects face, but an evaluation of the exposure outward from that point will be taken into consideration. If the focus point exposure is given more prominence, then this system is truly remarkable.

Edit: This scenario is based on the camera being in evaluative mode, correct?

Cheers

Wayne

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"Every day the world turns over on someone who was just sitting on top of it."

In evaluative choose an AF point shoot then change it from or towards a constant lightsource,your metering should be different.

I just put my 7D on tripod in evaluative. In same conditions centre to outer right AF I was metering -1 to -2 so TTMartin is right.

Thanks,very groovy.

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Cheers Mike

That is correct.

And, which is why I cringe whenever people recommend not using Evaluative Metering.

If you are shooting manual, I can see taking a spot meter reading, and setting your Tv, Av, and ISO.

But, if you are using any sort of automation in the camera P / T / A or Auto ISO, you are much better off using evaluative metering and if needed exposure compensation.

He is wrong and doesn't understand the camera properly, Wayne.  What I told you and what TTMartin told you is correct.  That's the way it works.  In evaluative mode, the camera moves the strong "center evaluation to the selcted point.  It effectively center weights whichever point you have chosen, including the outer points.  So it is an evaluated exposure, he's right about that, with some input coming from all over the frame.  But, the strongest weight centers around whichever point you have selected -- not just the center.  (See PP 269 of the manual)

Dale, which focus point did you select, was it the center focus point, or was it one of the outer points?

I moved the point selection around and tried selecting several different focus points on a scenic.  Some points were on light areas, then I moved to some on darker areas.  I could see the scene exposure change depending on which point I selected, even though the center point stayed in the same place.  ie., the camera was on a tripod shooting the same scene, and with point selection I could see the exposure change.  When I selected a point up in the sky, then in made the scene look darker.  When a selected a point in deep shadow, then it made the whole scene get lighter.  There is no question, in evaluative mode, the selected point heavily weights the exposure.  Try it for yourself.

edit:  When I read PP 269 in the manual, which I referenced for you.  It said 'linkable to any AF point'.  I may have had to do a link operation to achieve what I and TTMartin have told you about.  I can't remember.  But I know that my camera is linked, so that the in evaluative mode, the strong exposure weighting follows the selected AF point.  Try and see if yours is linked.  I can't remember doing it, but I may have had to link them.  This much I am positive of, the camera can do it!!

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kind regards
Dale

As you've realized by now, spot metering only reads a very small portion of the scene, around 3% if memory serves me. And how many compositions have the point to be metered sitting right in the middle? Not many as we both know.

If you're going to insist on using this metering style you'll need to accept that it will require some extra work. I fully understand the value of this metering mode and use it mostly with extreme back lighting of a subject. My technique is to compose the scene and adjust the AF point, then recompose with the center AF point on the subject to be metered, press AE lock, recompose to my original composition, half shutter press to confirm AF, and then take the picture.

This requires a bit of work but the results are always metered correctly. With practice this technique can be accomplished in the matter of maybe 2 or 3 seconds.

I'm personally not overly impressed with the 7D evaluative metering and switched to center weighted metering a couple years back. When shooting high contrast scenes the 7D (at least mine) would consistently overexpose the image. I sent the camera back to Canon for a check up and the work order stated "camera was working within specifications" and that "metering was calibrated". When I read reviews here on DPR this tendency to overexpose high contrast scenes pops up on some of the best DSLR's around.

Or the very opposite, like in gigs shooting a performer.

Always something isn't it?

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Cheers Mike

A good point.

Yes, it is.

Every Canon P&S I own allows spot metering at any selected AF point. I suppose they'll eventually relent and add this feature to at least the higher end cropped body cameras. But that might take a few years.

Until buying the 7D, evaluative metering was almost all I ever used. My 300D and 40D consistently expose scenes properly that the 7D struggles with. It's a shame too since the 7D metering is supposed to be a more mature product.

I have a cousin that literally uses spot metering all the time and wonders why the exposures all over the place. It's the least used metering mode for me by a considerable margin.

Could it be the metering of the 7D is better and you need to change your metering routine?

If I say something silly just let me know and I can learn

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Cheers Mike

Anything is possible. It could certainly be a short between the headset.

I ran around with the 40D and the 7D for awhile trying to get the metering sorted out. Both were set to evaluative metering with various AF points selected. The 40D almost never got it wrong. At a Canon seminar a few years ago the tech had a nice slide show on the 40D metering, the evaluative metering also links or weights the exposure based on the selected AF point. There's just something odd about the 7D even though they claim it is within specs. I've moved the 7D AF point around to different areas in a scene and see the exposure varying so I know that part of the metering logic is working. You can also see this in Live View when you move the AF point to a darker area in a scene.

A few months ago I was out give the 300D some exercise and was impressed by the metering, it was uncanny how well it performed under conditions that would fool the 7D.

I moved up from T1i (500D) to 7D and don't find anything wrong. I use single point AF so maybe using multiple I see the same thing you do, but for now i haven't. I will have it a go this week.

Interesting topic.

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Cheers Mike

If I have all 19 AF points selected the exposures are consistently better even though the metering should be technically weighted to the AF points that have actually achieved focus. But that's not my preferred choice. Most of my shooting is single AF point, next most used is AF point expansion, and Zone AF is a distant third. I normally have Spot and 19 point AF disabled via the menus.

FWIW: I use AE lock quite a bit with the 7D and that has minimized the amount of chimping required after a shot.

Maybe a silly question, all19? What did you get a 7D for?

Kick my ass if I missed out on something.

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Cheers Mike

I was only using 19 point AF in an attempt to figure out the evaluative metering exposure problems. Like I said, single point AF is the most used configuration, true on all of my DSLR's.