Day 187 – Metering

A quick look at metering functions on my canon camera, following on from this earlier post on exposure … cause practice reinforces understanding 🙂

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. Note: In the simulated viewfinder, Evaluative mode is shown with the left-most AF point active.  Evaluative metering is by far the most commonly-used system by EOS users

Spot: The most selective metering option, it reads exposure information only from the single exposure zone in the center of the frame (approximately 3% of the total picture area)

Partial: Similar to Spot Metering, but covers a somewhat larger area, reading only the cross-shaped central five metering zones (approximately 10% of the total picture area) — some shooters think of it as a “fat spot”

Center-weighted Average: This metering mode averages the exposure for the entire metering area, but with greater emphasis on the center metering zones. Unlike Evaluative metering, it does not compare brightness readings from different parts of the scene; it simply reads overall brightness.

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

But what does all this mean when I take a photo.

ISO500, 1/400 sec, F6.3,spot metering
ISO500, 1/400 sec, F6.3,spot metering
ISO400, 1/400 sec, F6.3,  partial metering
ISO400, 1/400 sec, F6.3, partial metering
ISO250, 1/400 sec, F7.1,  evaluative metering
ISO250, 1/400 sec, F7.1, evaluative metering
ISO320, 1/500 sec, F7.1, -2/3 exposure centre weighted metering
ISO320, 1/500 sec, F7.1, exposure centre weighted metering

First of all todo experiments like this, I need to make sure all the settings and the focus remain the same – so I should have used a tripod and manual settings… I didn’t 😦 , so we have changing ISO and changing shutter speeds. but this was a great concept to experiement with as the bee was very dark, the flowers bright and the background brightly lit by snshine, so to capture detail on the bee I needed to have full control of what light I exposed for. I think that with the bright background, spot metering did the best job.

I then had a little play with exposure compensation when I was at it… and I think this enabled me to get the best shot of the bee. You can see the detail in its wings, and although I used the evaluative metering mode, I took full control over the exposure – which is what happens of course, when you shoot manually.

ISO2500, 1/500 sec, F11, 1 1/3 exposure compensation, evaluative metering
ISO2500, 1/500 sec, F11, 1 1/3 exposure compensation, evaluative metering
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