Very straightforward spot metering question

chris321

chris321

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Chris
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Right, never used spot metering before, but might have to tonight. Just a really quick question, if I focus and recompose (and I know I shouldn't really, but let me off this once :D), does it do the metering when it autofocuses, or when you press the shutter?

I.e. if I focused on someone's brightly lit face, then recomposed so the face was in focus, but the centre was pointing at something very dark, would it meter for the face, or the dark bit?

Thanks sooo much,

Chris
 
chris321 said:
Right, never used spot metering before, but might have to tonight. Just a really quick question, if I focus and recompose (and I know I shouldn't really, but let me off this once :D), does it do the metering when it autofocuses, or when you press the shutter?

I.e. if I focused on someone's brightly lit face, then recomposed so the face was in focus, but the centre was pointing at something very dark, would it meter for the face, or the dark bit?

Thanks sooo much,

Chris
Click to expand...

What exaclty is wrong with focusing and recomposing the image :shrug:

It is a useful way of ensuring that you have the subject in focus wherever they might be in the frame. (especially useful when the camera has limited focus points) and it doesn't coinside with the desired lcoation of the subject.
 
I would imagine that when you recompose, the camera will meter for the dark in your situation.
Time to get to grips with the AE lock button
 
Just shoot in manual, meter your subject than when you focus and recompose your settings won't change.
 
Ok, say you have it set to spot metering, you half press to focus then recompose, where is the spot looking at the moment the shutter is pressed as that will determine exposure. If it is now looking at soething darker it will adjust the exposure and the face will be overexposed.

If you say are using evalutive metering, it will be looking at the overall light values of the whole scene, if the bright area ie the face has just moved and the overall light value of the scene is the same then the exposure will not change.
 
Not got the the book with me, so please correct if I go astray. If you focus on the the rarget area in spot metering you can press the * button on the camera, this will hold the exposure setting so should not change when you re-frame.
 
DrRusty said:
What exaclty is wrong with focusing and recomposing the image :shrug:
Click to expand...

Read this for a full explanation: http://visual-vacations.com/Photography/focus-recompose_sucks.htm

To answer the OP's question... if you're going to focus and recompose with the shutter half pressed, get the subject in the centre of the frame (that's where the spot-metering zone is on the xxD models) and half-press the shutter. This should lock focus and exposure. You can then recompose and shoot.

I'm pretty certain it doesn't but if the exposure does change when you recompose (I haven't used spot metering in a while so my memory is hazy), you'll have to use the * button to lock exposure, then focus and recompose. Just try it out and see what happens.

Just remember that the spot metering zone is in the centre of the frame. If you were using the other AF points, the metering zone doesn't shift to that AF point so you'd have to lock exposure, recompose, focus and shoot.

On a related note, does anyone know if the 5DMkII, 7D or 1D models have spot metering zones attached to the active AF point?

Hope this helps!

George.
 
Nikon have an AE/AF Lock button, so you can chose to lock the focus, or exposure or both. Dunno about Canon though.
 
martsharm said:
I know Nikon allow you to assign different functions to the AF-lock button, AE only, AF only or both together. So you can choose whatever you like.
Click to expand...

That's a good point, I'll have a look at the custom functions, I'm sure there was something in there!


DrRusty said:
What exaclty is wrong with focusing and recomposing the image :shrug:

It is a useful way of ensuring that you have the subject in focus wherever they might be in the frame. (especially useful when the camera has limited focus points) and it doesn't coinside with the desired lcoation of the subject.
Click to expand...

The majority of the time I'd agree with you, but I'm going to be shooting in low light, which means big apertures, and shallow depth of field. Focussing and re-composing can shift your subject just OOF, not enough to notice a lot of the time, but it's something I'd rather avoid.


KenL61 said:
I would imagine that when you recompose, the camera will meter for the dark in your situation.
Time to get to grips with the AE lock button
Click to expand...

That little button might be a bit of a lifesaver!


foggy4ever said:
Just shoot in manual, meter your subject than when you focus and recompose your settings won't change.
Click to expand...

Unfortunately I'm shooting a play, it's a completely new situation, I'm a bit out of my comfort zone, and I'd rather it not be my first time in complete manual!


artyman said:
Ok, say you have it set to spot metering, you half press to focus then recompose, where is the spot looking at the moment the shutter is pressed as that will determine exposure. If it is now looking at soething darker it will adjust the exposure and the face will be overexposed.

If you say are using evalutive metering, it will be looking at the overall light values of the whole scene, if the bright area ie the face has just moved and the overall light value of the scene is the same then the exposure will not change.
Click to expand...

Thanks for that. The reason I don't want to use evaluative is if there's a bright face and a dark background, it'll try getting something in the middle, overexposing the face, and still; keeping a dark background.


Mike54 said:
Not got the the book with me, so please correct if I go astray. If you focus on the the rarget area in spot metering you can press the * button on the camera, this will hold the exposure setting so should not change when you re-frame.
Click to expand...

This might be the solution!


BadgerLover said:
Read this for a full explanation: http://visual-vacations.com/Photography/focus-recompose_sucks.htm

To answer the OP's question... if you're going to focus and recompose with the shutter half pressed, get the subject in the centre of the frame (that's where the spot-metering zone is on the xxD models) and half-press the shutter. This should lock focus and exposure. You can then recompose and shoot.

I'm pretty certain it doesn't but if the exposure does change when you recompose (I haven't used spot metering in a while so my memory is hazy), you'll have to use the * button to lock exposure, then focus and recompose. Just try it out and see what happens.

Just remember that the spot metering zone is in the centre of the frame. If you were using the other AF points, the metering zone doesn't shift to that AF point so you'd have to lock exposure, recompose, focus and shoot.

On a related note, does anyone know if the 5DMkII, 7D or 1D models have spot metering zones attached to the active AF point?

Hope this helps!

George.
Click to expand...

Thanks a lot, good advice there :thumbs:

Off to play with the custom functions and '*' button now! Cheers guys!
 
my cameras set the exposure when you do the soft touch on the shutter
the problem is that it also sets the focus which may not be suitable
so i do a spot reading and then make sure the camera reads that when i compose
using...the +/- setting or on manual
spot metering is a means to an end and has to be used objectively
 
I think you can lock the metering by pressing the * button before you recompose.
 
I have the 1d and the 40d set up with Focus on the back " * "button and exposure Lock on the half press of the shutter button.

My shots are usually Focus, Meter, half press (Lock metered values), (re-compose if required) and Shoot

It retains the Exp lock for as long as i have the shutter button half pressed, independent of focus or composition
 
Remember when using spot metering(unless your creatively under or over exposing) to meter off a neutral mid tone in the image or subject.

I would meter from a mid tone lock the exposure in what ever way your camera allows,recompose and shoot.
 
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