Photo Settings B

***Camera Settings in a Nutshell 2***
by Bryan Pakingan

In the first round of information I went through the core units of exposure, sometimes referred to as the “trinity” by some photographers: aperture, shutter, and ISO.

Now I want to talk about some other functions of the camera. I will assume that you have a digital SLR in my guides, but some of these things might apply to point and shoot owners, and a majority should apply to film owners.

I will also assume that you have read about what shutter/aperture priority/and manual exposure modes do, and how each of them can affect your shots.

Therefore I will go over some relatively heavier concepts in this guide. I will not get too particular, but I do have books I can recommend to supplement this reading. I also recommend that you BUY these books if you are into photography and plan on making it a lasting hobby.

For this guide, the following book would make a great supplement:
- Understanding Exposure by Bryan Peterson

I will discuss:
1. How to Meter in a Nutshell
2. How to do exposure compensation (not flash exposure compensation)

How to Meter in a Nutshell

What is metering?:
Have you ever wondered how your camera calculates the proper shutter speed or aperture to achieve the “correct” exposure for your shot? In every camera, you have a meter that measures the reflected light off a subject (at least, most if not all cameras nowadays). This meter tells the camera basically what values you need for your shutter or aperture in order to get a “properly” exposed shot.

Will it be properly exposed every time? Unfortunately no because of the fact the meter can be fooled by extremely bright or dark objects.

One very important thing you need to know about is the function of each metering mode: evaluative/matrix, center weighted, spot/partial metering.

Types of Metering
I will skim through each function, but you can read more about what each does in your manual, and when one is usually used:

1) Evaluative Metering:
You camera meters clusters of the frame of the shot. By metering a number of clusters throughout the frame (more-so around the area where your focus point is at), the camera can make a guess of the correct values for “proper exposure” by averaging the values around these clusters.

This mode of metering usually fails when you have a subject that is significantly darker or brighter than the rest of the background because the averages will be thrown off.

2) Center-Weighted Metering:
You camera will meter off the center of the frame (usually where you see a round circle in the middle of the frame). So basically the metering is weighted towards the middle of the frame and this is where all the averaging will be done.

This mode of metering is pretty similar to evaluative metering so you will usually get similar results.

3) Partial/Spot Metering:
Usually in these modes of metering, you are metering off a specific portion of the frame only. Partial meters off a relatively larger area than spot metering. Spot metering usually will meter off the size of your “focus point” shown on the frame. Partial is like spot but it meters off a larger area than spot does, but much less than center or evaluative. Your manual will tell you how much spot and partial will meter for your particular camera.

You may want to use this when you want to properly expose something that is much brighter or darker than your background, if the background isn’t of much importance (there’s also other uses, but this is one of the important uses of it). If someone is dark and the day is bright, but you want to properly expose the dark person, you might want to use spot/partial metering and meter off the skin of that person. Therefore, the camera will give you the reading to accurately expose the person (based off their skin). As a result, the background will get brighter since the exposure will take longer, but at least the person will be properly exposed.

This is basically a method of selective exposing. Whenever you want to make sure something is exposed the way you want it compared to the rest of the frame, it’d be good to use partial/spot.

18% Reflectance:
Why is it that the meter gets thrown off when you are trying to take a picture of very bright or dark objects (like a white wedding gown or a black cat)? This is because of the fact that the meter only reads 18% of the light reflected off an object. Therefore, when something is very dark or very bright, it can get fooled. The way to make sure you have an accurate exposure in this case is to meter off an 18% grey card and underexpose the shot or overexpose the shot accordingly.

What the 18% grey card will do is give you an ACCURATE reading of the proper exposure under a particular light source. So let me give you an example.

Lets say you want to take a picture of a black cat in a regular day. You point your camera at an 18% reflectance grey card and your camera will give you the proper shutter speed/aperture value (depending on what exposure mode you’re in). Now if you point your camera at the cat, it will give you a different value for your shutter speed/aperture value (almost always).

The true value for that situation is whatever is reflected off the grey card. The value when you meter off the cat won’t be right because the cat is throwing off the meter. It’s telling the meter that it’s dark so you will get an overexposed picture overall because it’s compensating for the cat’s darkness. Therefore, what you want is to compare the shutter speed or aperture value metering off the cat, and the shutter speed or aperture value metering off the grey card.

Lets say you meter off the cat and it give you a reading of 1/100 of a second at f/4

Then when you meter off the greycard and it gives you a reading of 1/200 (as an example, this might not be the case when you do it), we now know that the reading is off exactly 1 stop (since you’re getting double the amount of light in the greycard reading opposed to the cat reading).

Therefore, when you take a picture of the cat, you want to adjust your shutter or aperture value so you’re one stop faster. In this case you’d adjust the shutter to 1/200 when you take a picture of the cat, or adjust the aperture to f/2.8.

This also applies to taking a picture of things that are very bright. It just requires overexposing instead of underexposing (as you can see, we underexposed in the cat’s case because we adjusted from the reading of 1/100 on the cat, to 1/200, so we made the shutter faster, therefore the camera gets less light).

How to use Exposure Compensation

Using the Exposure Compensation Dial:
If you’re using any of the aperture/shutter priority modes, you can adjust exposure using the exposure compensation dial. (It might be called EV compensation in your camera – exposure value compensation). But it usually looks like this: -2 ‘ ‘ -1 ‘ ‘ 0 ‘ ‘ 1 ‘ ‘ 2 (in 1/3 stop EV intervals). The negatives mean you’re underexposing, and the positive means you’re overexposing.

So if you were in Av mode (aperture priority) and it read 1/100 on the cat. You would set it to -1 (underexpose 1 stop) on the EV compensation and it would basically do the same thing as I stated above.

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Revised: 07/19/2008