20D Metering Modes

[Tparr]

The Canon 20D has three metering modes, Evaluative, Partial and Centerweighted. Is there a link anywhere that gives a more complete explanation of when to use each of these modes. That given in the manual seems to be very superficial. I would be particularly interested in which mode is best used when using a speedlight or flash. Thanks

[Jon]

You'd use partial when you only want to meter that central circle in your viewfinder. If you're considering a subject that spills out of that area, go to center-weighted. But most of the time, you'll want Evaluative, which assesses a number of areas throughout the field and determines the optimum exposure for the entire frame based on those readings and Canon's analysis of thousands (or more) photo exposure readings and subjects.

Basically, you can use Evaluative 90+ % of the time and worry about the others only if special cases arise.

[Tparr]

Thanks Jon! I have been using the evaluative mode most of the time but thought maybe I was missing something. I guess what I really need to learn is how best to use my new 580ex speedlite when using the Av mode.

[big_ipaq]

20D does not have a circle in the viewfinder, just in the documentation...

[kawter2]

20D does not have a circle in the viewfinder, just in the documentation...


Then you got jipped.. might want to see if the maker is CANNON vs Canon hehe

[robertwgross]

20D does not have a circle in the viewfinder, just in the documentation...

20D has a circle that is visible through the viewfinder, although it is probably found on the focus screen.

---Bob Gross---

[cmM]

it's only a matter of which part of the frame is metered for;
Evaluative (AKA matrix metering) divides the frame into a bunch of little rectangles (don't remember the number exactly), meters all of them and averages.
Partial - as mentioned above, only meters 9% (I think) of the frame ... the circle in the viewfinder - it does exist ;)
Center weighed - meters the entire frame but calculates exposure for the center of the frame (this is in between partial and matrix).

Now what you wanna use depends on what you are shooting. I use center weighed a lot, especially when shooting people - weddings, because it's important to get the subject properly exposed, the rest I don't care about. YOu wouldn't wanna use evaluative when you have a backlit picture, because it will throw your exposure off big time. If you shoot landscapes though, you want pretty much the entire scene exposed as close as possible, so you use matrix metering.... and so on :-P :D

[PacAce]

it's only a matter of which part of the frame is metered for;
Evaluative (AKA matrix metering) divides the frame into a bunch of little rectangles (don't remember the number exactly), meters all of them and averages.
Partial - as mentioned above, only meters 9% (I think) of the frame ... the circle in the viewfinder - it does exist ;)
Center weighed - meters the entire frame but calculates exposure for the center of the frame (this is in between partial and matrix).

Now what you wanna use depends on what you are shooting. I use center weighed a lot, especially when shooting people - weddings, because it's important to get the subject properly exposed, the rest I don't care about. YOu wouldn't wanna use evaluative when you have a backlit picture, because it will throw your exposure off big time. If you shoot landscapes though, you want pretty much the entire scene exposed as close as possible, so you use matrix metering.... and so on :-P :D
On the contrary, if you are going to be shooting a backlit subject, Evaluative metering would be the better choice than center-weighted average metering. The problem with CWA is that although it weights the center more than the rest of the scene, the center weighting isn't all that drastic. A strong backlight will "fool" the metering and cause the main subject to get underexposes. Evaluative metering, on the other hand, uses algorithms that evaluates the scene and, using a database of similarly lit scenes, tries to determine the best way to set the exposure to properly expose the more important subject.

In short, for your average scene shots, CWA is OK. For not-so-average scenes, you have to know how to "read" the lighting and set the proper amount of EC. \

If you are a beginner or can't differentiate an average scene from a non-average scene, then Evaluative will perform better for you most of the time than CWA.

[Todd Jacobsen]

On the contrary, if you are going to be shooting a backlit subject, Evaluative metering would be the better choice than center-weighted average metering. The problem with CWA is that although it weights the center more than the rest of the scene, the center weighting isn't all that drastic. A strong backlight will "fool" the metering and cause the main subject to get underexposes. Evaluative metering, on the other hand, uses algorithms that evaluates the scene and, using a database of similarly lit scenes, tries to determine the best way to set the exposure to properly expose the more important subject.

In short, for your average scene shots, CWA is OK. For not-so-average scenes, you have to know how to "read" the lighting and set the proper amount of EC. \

If you are a beginner or can't differentiate an average scene from a non-average scene, then Evaluative will perform better for you most of the time than CWA.

Wouldn't you want to use Partial for high contrast scenes (background vs subject)?

[kawter2]

Wouldn't you want to use Partial for high contrast scenes (background vs subject)?

depends how harsh your flash is when it lights the subject, but 90% i would say yes

[cmM]

On the contrary, if you are going to be shooting a backlit subject, Evaluative metering would be the better choice than center-weighted average metering. The problem with CWA is that although it weights the center more than the rest of the scene, the center weighting isn't all that drastic. A strong backlight will "fool" the metering and cause the main subject to get underexposes. Evaluative metering, on the other hand, uses algorithms that evaluates the scene and, using a database of similarly lit scenes, tries to determine the best way to set the exposure to properly expose the more important subject.

In short, for your average scene shots, CWA is OK. For not-so-average scenes, you have to know how to "read" the lighting and set the proper amount of EC. \

If you are a beginner or can't differentiate an average scene from a non-average scene, then Evaluative will perform better for you most of the time than CWA.

I was reffering to partial metering in a backlit situation, forgot to specify it :oops: . I didn't say center weighed is better in backlit situations, I just said I use it most of the time.

[PacAce]

Wouldn't you want to use Partial for high contrast scenes (background vs subject)?
Yes, you can use partial metering for that purpose, if you wanted to. The point I was trying to make was that evaluative metering will give you better results with backlighting than CWA metering would.

[SAZABI]

Ok... going thru all the replies, but I still don't know the difference between partial, and centerweighted....

sounds like the same to me... see if I interpret this wrong
partial - only evaluate the part inside the circle (isn't that the center part?)
center weighted - only center
:confused: what is the diff? help please....

[Marshy]

Ok... going thru all the replies, but I still don't know the difference between partial, and centerweighted....

sounds like the same to me... see if I interpret this wrong
partial - only evaluate the part inside the circle (isn't that the center part?)
center weighted - only center
:confused: what is the diff? help please....
Centre weighted takes a meter reading from the centre of the frame and averages it for the whole frame but partial takes a slightly smaller centre reading but just uses that for the whole frame it doesn,t average for full frame like the other two do , my understanding of it anyway , i,m still struggling to know when to use what for what scene !

[robertwgross]

Ok... going thru all the replies, but I still don't know the difference between partial, and centerweighted....

Page 71 in the manual.

---Bob Gross---

[SAZABI]

Centre weighted takes a meter reading from the centre of the frame and averages it for the whole frame but partial takes a slightly smaller centre reading but just uses that for the whole frame it doesn,t average for full frame like the other two do , my understanding of it anyway , i,m still struggling to know when to use what for what scene !

thank you! :)

[PacAce]

Centre weighted takes a meter reading from the centre of the frame and averages it for the whole frame but partial takes a slightly smaller centre reading but just uses that for the whole frame it doesn,t average for full frame like the other two do , my understanding of it anyway , i,m still struggling to know when to use what for what scene !
Center-weighted average metering takes the reading from the whole viewfinder area. The center area of the viewfinder is then given a little more weight than the other areas in the viewfinder (and hence the name center-weighted). The newly derived reading over the entire viewfinder is then averaged to arrive at the exposure reading.

[SAZABI]

oh, i got it now. thx PacAce