Mark III metering

[VirtualRain]

Evaluative metering has frustrated me at time as well, but you need to realize that it gives emphasis to the focus point... and if you're like me, you tend to choose a focus point with high contrast in a scene, and something well lit... that tends to be one of the brightest elements in the scene, and as a result, all my shots done this way come out underexposed.

There's a couple of solutions to this...
1. Business as usual but adjust exposure in post
2. Business as usual but use exposure compensation at the time of shooting
3. Focus and meter on something that's more neutral (mid-tone) and likely get a more pleasing and proper exposure but risk missed focus because your point is not high contrast (maybe less of an issue with the 5D3 and therefore a hard habit to unlearn for those of us coming from lesser focus systems)
4. Meter and focus separately (although this will require experimentation as well to determine what kind of point to meter off to get the right exposure, so I'm not sure it's going to be any better in the end and at least initially probably lead to a lot of poor shots)

Spot metering is not the answer for most of us... it's really for subjects who are not going to get exposed correctly because of strong lighting elsewhere in the scene and where you're willing to sacrifice shadows or highlights in the scene to make sure your very specific target is exposed properly. In most cases, the situations that require spot metering are not going to yield a nice picture, so it's best to think about what you're doing and adjust your angle/composure.

 

[jrista]

Photogs who are coming from an older Canon camera (like the 40D) have to remember/realize that the 5D III has a color metering sensor. It has two layers, the first sensitive to blue-green light and the second sensitive to red-green light. The iFCL meter also takes into account scene focus (even if you are manually focusing), and weights metering to the focused subject. The old Canon metering sensors prior to iFCL were really only sensitive to red light, ignored focus, and that resulted in rather inaccurate metering.

The Canon 5D III meter should be a FAR more accurate meter, and it should be far better at recognizing bright highlights (which have blue and green light as well as red), so your histograms are going to fall closer to the center than the right. Be careful about over-exposing as well. Canon sensors offer a lot of highlight headroom, but a scene can appear to peak in the midtones and stop on a histogram because the quantity of bright highlight pixels is relatively very low in comparison. Overexposing to make a 5D III histogram look like a 40D histogram could very likely blow all your fine highlights. That may be acceptable if you don't overexpose the rest of the image and the blown highlights look appropriate for the scene, and you can probably gain a LOT of shadow DR by doing so...but there are tradeoffs.

It took a little bit of time for me to get used to my 7D iFCL meter when coming from a 450D. I noticed that most of my histograms in LR bulked up in the near-highlight midtones, where as with the 450D they would bulk up more in the highlights themselves. I tend to overexpose the 7D by 1/3rd to 2/3rds of a stop, and I rarely ever actually blow the highlights, but it is often very hard to see if there ARE bright highlights with the in-camera histogram (thanks to the wonderful use of JPEG previews to generate in-camera histograms...wish Canon would provide a direct-meter histogram of some kind in real-time to better indicate tonal distribution before taking a shot.)

 

[swrightgfx]

The nature of evaluative/matrix metering is prone to underexpose an image if a bright light source or surface is present. Technically using the term "underexpose" is not suitable, because it is still an accurate exposure based on what you have requested the meter to do - average the scene. This is most likely why images often appear underexposed when shot indoors (as others have complained about above). There are windows, doorways, reflective surfaces like white walls, etc. When these hit your meter, it flips out and cuts them down in an attempt to hit 18% grey.

This is why other metering modes like spot or centre-weighted average (in the case of a centred area of focus) exist. So, if your mother Jane standing by the window facing you is underexposed while your father Joe is illuminated like Blackpool in festival time, it is probably best to either spot meter to the subject you most want correctly exposed or ask Jane to move away from that window!