Photography Tutorial: Metering.

Metering: Most cameras have a built-in light meter that measures the amount of light in a scene and allows the camera to adjust the shutter speed and aperture for a proper exposure. To meter is to take a light reading.

Before we go on, you should be aware that:
- The AE/L means Exposure Lock on a DSLR/SLR or any other camera that has that button, if you press and hold that button it will lock the exposure data that you metered.
- If you depress the shutter half way and hold it, on most other camera, that is the AE/L and AF/L most likely, which means Exposure Lock and Auto Focus Lock.
- You can meter whatever you want, lock your exposure, and recompose the scene.

First of all, i would like to explain to you that there are generally 3 types of metering:

Matrix / Pattern / Multi-Pattern Metering:

It measures the lights of the whole scene + the camera makers own formula to give you the best reading.

Center Average Metering:
It measures only the center of the whole frame, and averages it out.

Spot Metering:
It measures only the Very center of the frame, and gives out the reading.

Why do we need to know specific methods of metering:
Most of the time in more tricky lighting situations, but still want the ability to Not shoot in manual, we can simply change the metering method and also need to choose where and how to meter your scene.

Example:
In a concert like the photo below:
Pattern: CenterAverage:

Reason why you should use Center Average Metering?
It is because the lights off the stage are much stronger than the surrounding area (walls). If we use pattern metering, the meter will try to correct itself, to make the surrounding a little brighter, but, at the same time, the brightness of the whole orchestra will actually be over exposed, and we are shooting the orchestra, not the wall, right? So, what you should do is, use the center average metering and metering at the orchestra itself, to get a better result.

When to use Spot Metering?:
If the object you are trying to meter off is smaller than the center average metering area, you might want to switch to Spot. Or, if you are doing selective metering, you might also want to use spot, to pin point where exactly you want to meter.

Selective Metering:
When the Patter Metering Fails. You can decide where to meter on your own to get a better result, this is really handy especially on most digital camera nowadays you can see the immediate change on the LCD screen of the whole scene. And its time to use Center Average or Spot Metering.

To Show you the difference of metering at different spot of a scene. Using a Canon SD800 IS point and shoot digital camera:

-The first photo is spot metered at the light casing itself. The casing is black = dark , thus the over exposure at the whole scene.

-The second photo is spot metered at the top left corner of the LCD screen at the wall. Results in better exposure. But at the bottom left of the computer its overexposed.

-The third photo is spot metered at the bottom left corner of the computer (right above the word "Satellite"), result at a slightly darker exposure but notice nothing is over exposed.

1.) 2.) 3.)

Some might say the "prefect" one is dark. Yes it is, and i am not saying that one is absolutely prefect but that one is Not overexposed at anything, and not way too under exposed on too many things especially the important objects minus the wall. You can't add in whats lost (overexposed), but you can always bring back up the shadows in processing. To lighting this whole photo up, just use the curves. *And for those who does not agree with me on this, i am sorry and please just ignore this part and try not to argue too much*

Case Study:
Now you see what difference it makes when you meter at different spots, convert this info when you are encountering over exposure in a scene. Such as but not limited to. Taking portraits of 2 people standing in front of a brighter background eg.(person are indoor and behind them is a big glass window), and the background is a larger area then the 2 person. Chances are, if you use pattern metering, the 2 people will be underexposed because of the large bright background.

To correct this:
- We can use Center Average Or Spot Metering, it depends on how big the area is we are metering. Spot probably works more precisely.

- Now We need to look at the scene. Determine where we are gonna meter, logically, we are going to find a spot that is average between the dark people and the brighter background.

- We do not necessary want to meter just anywhere on the person, because that would result in the over exposure at the background. its more than that.

- Pick a spot with the lighting that is average between the background and the people. Be aware, color of objects DOES matter (Explained below), if you are metering the persons dark color clothes, that tells the camera, its dark, and light color clothes meaning its, bright, most of the time with most cameras.

- So look for the color that is in average tone, nothing too dark or bright again, average. Most of the time, we can start trying to meter at the light blue jeans, or, the person's skin tone (depends on skin color), it also can be a shirt they have on, if we fail to find the color on the either person, look around the floor or something right next to them.

- Do the AE Lock as mentioned at the top of this article

- Recompose the Scene, and Shoot.

- Grab your camera and try it until you understand it all.


*Last, but not least, to show you why the colors DOES matter*
Photo 1.) Metering the blue color
Photo 2.) Metering the purple color

1. 2.

Photo 2 is brighter than photo 1, because, purple is a darker color, so it tells the camera is darker, but in reality, its side by side same lighting condition. This is just an example for color difference, but of course, if you use pattern metering in this case, its a perfect exposure.

Now you can use your camera in a more flexible way, enjoy. You got it, might as well use it.

2008 March WTF