Pro Pix Tips: Speaking Meter Language

Hi everybody! As promised, I'm posting a Pro Pix Tips on metering. So let's get right to it!

I few years ago (there's that phrase again) I called my brother about making a purchase of something that I have forgotten what it was so don't ask cause it don't matter now. I do remember telling him that the price was a large percentage off I guess in an attempt to gain some kind of uh aw response. Instead, what I got was this question; "Percentage off of what? Compared to what?" I tell you this because as we go into this Pro Pix Tips we need to remember that when we talk meter language we have to remember that the basics of metering is based on comparisons. Meters are pretty high tech nowadays but I still haven't found one that reads the photographers mind or correctly identifies the object being photographed and what kind of details the photographer is trying to capture. If you went out and tried to do the suggested assignment of taking a picture of the moon, you would have at least a vague idea of what I'm talking about here. For you that just didn't get motivated enough to do the shots of the moon I will at least touch on it a bit. But to do so I will talk to you as though you did the assignment. Where you surprised at the fact the speed, aperture, and ISO settings were at least comparable to settings you would use during a sunny day? In fact, did it surprise you when you took the picture that the moon came out like a all white ball with little if any contrast to it and just all white even though the meter appeared to be set perfectly on the exposure? How long did it take before you realized that the speed and aperture would have to be set so that the meter gave every appearance that the picture would be under exposed only to find the picture finally yielded out a great picture of the moon along with all it's craters and plateaus? I direct your attention back to the words of my bother.

Simplifying things a tad, most meters today are calibrated to take there readings on items of the photo that fall in the mid tone areas. Things like green grass and tanned skin would be examples of mid tone items. Ansel Adams, a world renown photographer who best know for his work in black and white photography, came up with a chart that named and showed the steady progression of shades from pure black to pure white. He named these zones and labeled them from pure black as zone 0 to pure white as zone 9. In the middle of this shaded zone areas was zone 5 making up the mid tone range. Now keep in mind that pure black absorbs 100% of the light (theoretically) while pure white reflects 100% of the light (theoretically). In between we see varying amounts of reflected light and at varying frequencies which we call colors. With respect to camera meters, they deal with zones 0 to 9 in judging the exposure of a picture. It just so happens that a perfect grayscale level zone 5 reflects 18% of the light that is shining on it (for you more enlightened photographer, does the 18% thing sound familiar? Think white balance!). If you are pointing your camera at a dark surface, the meter is comparing the shade of that surface with zone 5 or mid tone region and, thinking it is metering a mid tone surface, is giving a reading based on how much more or less light is need to make that mid tone surface to reach zone 5 shading. Now as I said, this is a over simplifying of the subject but does give a base concept understanding of how the meter is giving the readings it does. Now other things do come into play such as the type of metering you are using. There are three basic types of metering; spot, center weighted, and matrix. While meters vary some with each manufacturer, with the Nikon cameras I use, these basic meter settings are at least similar enough with other brands that you should get the basic idea.

Each camera has a certain number of measuring point. The more point the better in most cases. Switching between the types of metering settings directly effects how the measurement readings from each of the points is considered. In spot metering only a small portion of the measuring points (amounting to about 2% to the overall picture being taken) is considered. Whatever light or lack there of is in that small area is measures, averaged, and compared to the mid tone level with a reading given accordingly. The other 98% of the picture area is not considered. In center weighted metering, all the measuring points are considered but with center portion of the picture having a much higher degree of consideration then the rest of the picture area. In many of the cameras, the amount of weighting and the amount of the area that makes up the center weight portion of the picture is adjustable. In the Nikon I use the ratio of weighting is 75:25 with the 75% part of the reading taken from the center of the picture and the remaining 25% from the area of the picture outside the center. With the matrix setting, the entire area of the picture is being equally considered. And remember that the meter is taking the average of the levels of light reflected and comparing it to the mid tone region. Now let me make a correction of sorts. With matrix metering or metering which considers the entire area of the picture, the Nikon at least, uses a thing call scene recognition to compare the picture you're taking and compares it to a data base of thousand of image with different characteristics and matches the two with the meter reading coming from there. But folks this is a Pro Pix Tips not a college course.

The idea here is to show you how easy it is to get a reading from your meter that may not jive with the photo you get. Let's look at the moon picture for a second. The area that the moon is occupying in the view screen effects how the meter reads. Remember, the light is being averaged. That is why your picture of the moon is so over exposed even when the meter says it's perfectly exposed. That also explains why you can get some great photos in low light conditions that the meter says you can't get.

When you're focusing and taking meter reading be sure to note what your meter is taking it's reading off of. Remember mid tones is what the meter is looking for. What type of metering settings are you using? How much of the picture is being considered in the reading and how much dark and light areas are within the metering's area and which if any is more dominant.

One final tip is to take the picture anyway no matter what the meter is saying. Look at the results yourself and make the call. Just remember about the ISO factor as it pertains to "noise" in your picture in low light conditions. The meter is a valuable tool but it should not control you completely. You take control and responsibility for taking and judging the picture. You brought that picture into this world with the shutter and you can take it out with the trash can.

Well as promised, I brought a Pro Pix Tips and I will plan on doing another one really soon. Hope this one was a help in understanding your meter a bit better. Have a great day everyone and happy Labor Day!

Richard