How to get correct exposure?

[john_t]

I have been using a "point and shoot" camera for the longest time until I recently dove into a Nikon D80 DSLR.

I have been reading a lot of books on photography, especially the ones by Bryan Peterson. What confuses me the most was how he gets his exposure by metering off the sky or green colored objects. The technique is new to me and I do not understand it. Previously with my "point and shoot" camera, I just aim my camera at the subject and take the picture.

Does it matter which section of the sky I meter off of? Do I measure the sky that is directly above me or just the sky in front of me by the horizon? What if the sky has different shades of blue. Does metering off of the darker section affect my final result? How do I pick a "neutral" area of the sky or green leaf to use as reference for my metering?

Thanks

[thazooo]

The author uses the sky or green grass to get an exposure value because in nature these colors are closest to 18% gray. 18% grey is the tone range that your camera meter is calibrated too. In theory if you meter off the sky or grass, lock the exposure, and then shoot; you will have the correct exposure.
This works when the subject is equally lit. Contrasty scenes or white objects in the shot will change this.
Try this, put your camera in spot meter mode. Choose a scene with varying tones. Meter off a tone range and shoot. Select another tone range, meter and shoot. Do this for several tone ranges. When done look at your shots and you will see how different meter readings change the appearance of the image.
Also do a search on exposure, theres a ton of articles out there.

[rickl52]

I'm not familiar with the author but finding one portion of the scene for which one can predict the correct exposure is a variation of the zone system. Try googling "zone system" and you'll get hundreds of hits. It was developed by Ansel Adams and has been adapted by many for the more limited range of digital cameras.

The basic idea is to meter off something which you know, by experience, falls right on or predictably above or below neutral exposure by give amount. When you find a list of specific things (light skin, dark skin, grass, blue sky, etc...) and where they fall relative to neutral exposure you'll get the idea.

For those who do primarily portraits, most can meter off the face of the subject and know, by the tone of the subject's skin, if the camera should be reading at, over, or under neutral and by how much to end up with the correct exposure for the scene.