question light metering modes

[gail]

Don't know if I'm in the right place to ask this are not. didn't know what forum to post to for this question. But anyway here goes.

Witch one of these is most used and why? I don't quite understand witch one of these I need to use. I'm confused. :?

Evaluative
Light Metering

Center-Weighted
Averaging

Spot AE Point

Is there a need to change this at different times?
mind usually stays in the Center mode. I've never really notice it till now. I just happen to hit the button one day and was thinking now what is this?

So witch one of these do you all mostly use? :?:

[Scottes]

Well, on the 10D...

Evaluative splits the view into 35 zones and averages them to get a good overall exposure of the entire scene. It leans towards the area around the active focus point. Even if you use the center focus point to focus and then recompose you're most likely to get a decent exposure because it averages the entire scene. But it's best to use all 7 points, or manually choose the point that falls on the subject. This is generally a good, safe mode that will work most of the time.


Partial looks at the 9.5% of the view in the center circle displayed in the viewfinder. This allows you to properly expose a specific subject and basically ignore everything else. If you use the center focus point to focus and then re-compose you just about always DO NOT want this mode. (Unless you also use AE lock, too.) If you have a scene where your subject is dark but the sky is bright this mode is for you - but you probably have to combine this with AE lock.

Partial is also good if you move your camera around the scene looking at the exposure values for specific areas. This would give you an idea of each light zone in the scene. Then you could flip to manual or adjust EC based on the info gathered from the scan.


Center-weighted looks at the entire scene but weighs heavily to the general center of the view. If you always put you subject in the center of the frame then this is for you. Otherwise you probably do not want it.

[shniks]

Hi Gail, I only just started playing aroung with this function. I normally use evaluative metering for most shots. It takes the best overall reading.

However, on the occassion when the main subject has very different lighting to the background I have been using the Spot AE point, because it concentrates on getting exposure right for the subject, not the entire scene. It does this by exposing for whatever is in the green box on the lcd, so make sure your subject is in there, or you can lock the exposure on the subject first then move the camera.

[stopbath]

For most subjects (snapshots) you can get away with evaluative metering which looks at the entire scene, and compares the scene to a database of scenes (landscape, portrait...) it renders a pretty decent guess.

Center weighted is more of just a guess putting more weight on the middle portion. Its a good guess.

Spot meter ignores everything but the green box. No guessing.

Generally, use Evaluative for snap shots as it can generally handle most things. But complex scenes (back light, or strong side lighting) may require spot meter.

All meter readings will try to render all pictures as middle grey. Have fun.

[pradeep1]

Spot metering baby. Once you get used to the controls and thought process involved in using spot metering, you photography will improve considerably.

[gail]

Thanks everyone for the replies. I'm still just kind of playing with the 3 trying to see the difference in them but have not yet notice any difference in using them. May be I'm doing something wrong.

But to me I've taking pictures using all 3 of them and they look the same. So maybe I'm I doing something wrong are should there be a change in the pictures? I will just go play with it some more till I figure it out LOL.

Thanks,, :lol:

[Scottes]

Find something white and something black, preferably about the same size. Sit them up on the sofa or something that's a mid-color, like a medium blue or grey or green. Place them somewhat apart from each other.

Put the camera in Partial metering mode (center-only), Av mode and center focus point. Set it to f/8 and keep it there. Using flash is OK. Aim at the black thing, take a picture, aim at the white thing, click, and in the middle, click.

Try to set it up so that the middle shot doesn't have either thing near the center circle. Make sure that both the white and black things are visible in all the shots.

When you aim at the black thing the camera thinks that it's not reflecting enough light if it were medium grey, so it adds exposure time. This means the black thing will show up as grey, and the white thing should be far too white or even blown out.

When you aim at the white thing the opposite happens. The camera thinks that the white thing is reflecting too much light if it were medium grey and reduces the exposure time. The white thing will come out greyer, the black thing will be very black and lose all detail in the blackness.

When you aim in the middle the picture should be more actual. The mid tone in the sofa/whatever reflects just about the same amount of light as if it were medium grey so the camera thinks it's perfect and exposes perfectly. The black thing is black and the white thing looks white.


Push the white and black things close together and flip to Center-weighted mode. Aim so the white thing covers the center circle but the black thing is still in the picture somewhat. Take a picture and then aim at the black thing and take a picture.

With center-weighted the camera comes closer to averaging but pays more attention to the object within the circle. So for the "white" picture a lot of white + a little black = bright gray, so the camera will subtract *some* exposure time. The white thing will be bright grey, the black thing will be too black.

For the black picture, a lot of black + a little white = dark grey, and the camera will add exposure time, so the black thing will be dark grey and the white thing will be bright white but not blown out.


Now set the camera to Evaluative mode and push the white and black things close together and take a picture. Since the camera is averaging things out, black + white = grey, so the exposure should look pretty close to perfect. A black and a white thing in the same picture is too much of a range for the camera, but they should be close.


Also, since you left the camera on Av and f/8 the only thing that should change is the shutter speed. Check the EXIF info and compare shutter speeds.

[cell0518]

Thanks for the info. Was wondering the same stuff, so this seems to explain it. I'm going to try this out. :)

[digitallure]

Wow. Very good ifno. I had no clue. Thanks!

[vinunleaded]

wow good stuff
you pretty much explained everything that the books try to explain to me


Find something white and something black, preferably about the same size. Sit them up on the sofa or something that's a mid-color, like a medium blue or grey or green. Place them somewhat apart from each other.

Put the camera in Partial metering mode (center-only), Av mode and center focus point. Set it to f/8 and keep it there. Using flash is OK. Aim at the black thing, take a picture, aim at the white thing, click, and in the middle, click.

Try to set it up so that the middle shot doesn't have either thing near the center circle. Make sure that both the white and black things are visible in all the shots.

When you aim at the black thing the camera thinks that it's not reflecting enough light if it were medium grey, so it adds exposure time. This means the black thing will show up as grey, and the white thing should be far too white or even blown out.

When you aim at the white thing the opposite happens. The camera thinks that the white thing is reflecting too much light if it were medium grey and reduces the exposure time. The white thing will come out greyer, the black thing will be very black and lose all detail in the blackness.

When you aim in the middle the picture should be more actual. The mid tone in the sofa/whatever reflects just about the same amount of light as if it were medium grey so the camera thinks it's perfect and exposes perfectly. The black thing is black and the white thing looks white.


Push the white and black things close together and flip to Center-weighted mode. Aim so the white thing covers the center circle but the black thing is still in the picture somewhat. Take a picture and then aim at the black thing and take a picture.

With center-weighted the camera comes closer to averaging but pays more attention to the object within the circle. So for the "white" picture a lot of white + a little black = bright gray, so the camera will subtract *some* exposure time. The white thing will be bright grey, the black thing will be too black.

For the black picture, a lot of black + a little white = dark grey, and the camera will add exposure time, so the black thing will be dark grey and the white thing will be bright white but not blown out.


Now set the camera to Evaluative mode and push the white and black things close together and take a picture. Since the camera is averaging things out, black + white = grey, so the exposure should look pretty close to perfect. A black and a white thing in the same picture is too much of a range for the camera, but they should be close.


Also, since you left the camera on Av and f/8 the only thing that should change is the shutter speed. Check the EXIF info and compare shutter speeds.

[vinunleaded]

quick question
Lets say if I want to take a picture of my wife against the bright sky and I want to properly expose for my wife. What metering mode should I use if I put my wife somewhere else on the frame other than the center? Do I use Partial metering, then manually select the focus points?

[Wilt]

quick question
Lets say if I want to take a picture of my wife against the bright sky and I want to properly expose for my wife. What metering mode should I use if I put my wife somewhere else on the frame other than the center? Do I use Partial metering, then manually select the focus points?

Partial or Spot only work in the center. If you want to use other focus point to meter from, you need to be in Evaluative and select your focus point, and the metering occurs at that same position (when using Canon)

[PhotosGuy]

Is there a need to change this at different times? I usually don't, but I use this:
Need an exposure crutch? (http://photography-on-the.net/forum/showthread.php?t=89123)