What is Metering

Oh metering, how wonderful you are if done properly! You make my photos come out perfectly exposed saving me LOADS of work in photoshop. Thank you meter, thank you. So what's a meter and how does it work? Well, here is where I tell you all that I am a science nerd and on top of just loving camera's and photos I love figuring out how things work. I was that kid who took the clock apart and could never get it to work properly again :) Be prepared for information overload sometimes and I'm going to go really basic here. The meter is the little graph in the bottom of your camera view finder that tells you where your exposure should be when setting all of the settings manually and if in auto mode it will set exposure for you to the middle of the graph.  Every DSLR camera has one and their main goal is to expose a picture for something called middle gray (18% gray, 18% of incident light, gray card etc.. Middle gray has a few names). To do this it reads the reflected light of the entire scene (evaluative metering), averages it and comes up with an exposure that would suit middle gray exposure , meaning nothing is pure black and nothing is pure white if at all possible (this can be viewed as a bell curve on the histogram, which is a whole other blog post!). The short of it is that your camera's meter likes a photo where there are no extremes, there is an even distribution of color throughout. Of course when photographing a bride in a white dress and a groom in a black tux things can get tricky because where is middle gray? If the camera is aimed directly at any object lighter or darker than middle gray, the camera's light meter will incorrectly calculate under or over-exposure, respectively. That's where spot metering comes in. To spot meter the camera just meters for the center of the scene so if the tux were in the center it would overexpose the dress and if the dress were in the center it would underexpose the tux. The photographer has a lot more control over what is exposed correctly and what is not. And lets face it, a lot of the time there is some extreme in the shot and a choice has to be made, what to blow (overexpose) or what to underexpose.

Here is a great intro to metering article if I've totally got your head spinning!


I use evaluative metering (exposing for the whole scene) most of the time but my camera shoots dark so I always "overexpose" a stop or two (one or two tick marks to the right of center on my canon 5D) on everything. This ensures proper exposure most of the time for me. I could go into my camera's settings and change the exposure compensation but I'm used to it now and I'd probably start blowing everything! I think each cameras meter is unique so practicing and figuring out how your camera exposes is important.  Just because that little tick mark is in the center doesn't necessarily mean you'll end up with the exposure you want. When I'm in a tricky lighting situation, say back lighting, where there is a light source coming from directly behind my subject I will always spot meter for their skin tone. When I was learning this process I would just get really close to the person and fill my view finder with all skin, set my settings for proper exposure then step back and ignore the exposure because I knew the skin was what I metered for. Now I just shield the light source, my hand is usually in the view finder, I meter then pull my hand back and viole! A nicely metered photo with personal space still intact :) Some people use a gray card. They hold the card in front of the camera, filling it with gray then meter. Theoretically this sets the meter perfectly but what, in reality, it doesn't do is allow you to expose for the subject you want exposed properly. You may end up with a slightly underexposed tuxedo or a slightly overexposed dress and oh how I hate an overexposed dress! You don't have to go out and buy a gray card either if that method seems easier for you. You can easily substitute something in your surroundings for 18% light. Just look for something, any color, in the same shade as 18% gray. A beige wall, a shaded sidewalk, a light blue chair, anything will work really just so long as it's not black or close to black and it's not white or close to white. BTW this is 18% gray;
  Amazing, isn't it!? Ha!!

So that's what I know about meters... and I'm stickin' to it ... unless someone has a better idea :) What do you all do? Spot or evaluative? Any tricks of the trade you've found helpful in nailing exposure in camera? Thanks Lisa for a great question!! And please, if anyone wants to tackle a question posed please feel free to! Again, I am by no means an expert... I'm just a little nerdy ;)