Getting the right exposure the first time

Started Jul 8, 2012 | Discussions thread
Veteran MemberPosts: 8,373
Setting Exposure - Part 2
In reply to Marathon Man, Jul 8, 2012

Nikons provide various options for practicing exposure. Of course, you should use Spot metering, as Center Weighted covers too large an area to evaluate effectively, and Matrix is a completely separate animal that applies EC for you definitely don’t want to use that. Spot metering will let you isolate and evaluate tones.

Manual mode requires the least amount of thought to use, and is a bit I tend to avoid it. I only use M mode when the meter doesn’t work, as with astrophotography, fireworks, certain types of flash photography, etc. Otherwise, if the meter works then I’m using an auto mode. Manual mode’s only advantage is that once you set exposure, the settings don’t change. However, that’s only somewhat helpful in constant-light conditions, and useless in changing light conditions. With manual mode you simply adjust your aperture and shutter while viewing your Exposure Display in the viewfinder. If you are spot metering light skin and want to overexpose by +1, then you simply adjust your settings until the meter indicates an overexposure of +1. Now your exposure will be correct.

I prefer auto modes (P, S, and A) as I gain much flexibility and speed over manual mode. To facilitate the use of auto modes, I make two changes to the camera settings. First, I set the AE-L button to “AE Lock (Hold)”. Second, I set the Auto Meter-off Delay to 30 minutes. With these two changes I can now lock an exposure level and keep that level for multiple images. I also make a third change, just a personal choice. I enable Easy EC...that places Exposure Compensation on the unused command dial full-time.

So here’s how you’d set exposure with auto modes. First, spot meter your subject...say it’s a light-skinned face. Next, press your AE-L button. That’s locks the exposure level. Finally, you apply +1 of EC. Take your shot, and you’ve got correct exposure. But how did that happen?

Auto modes perform a single act of automation...that of providing Standard Exposure. That’s the same as centering the exposure indicator in manual mode. So you can view auto modes like a manual mode where the meter is continuously centered. That’s all that auto modes do. Once you understand this, you can see that exposure is easily and fully controlled using the EC function. In fact, when you apply EC, your Nikon will display the amount of EC using the same Exposure Display that manual mode uses to set exposure. That is to say...when +1 exposure is set in M mode, and +1 EC applied in PSA modes, the Exposure Display looks exactly the same.

By locking exposure with the AE-L button you can now point the camera at something else, and the exposure will be correct as long as the light remains constant. In this way, it’s the same as M mode. However, using an auto mode provides greater flexibility. With your exposure locked and compensated, you can now change your settings. So if you’re in A mode, you can now select a different aperture and the camera will adjust the shutter to maintain the locked exposure level. This is great for experimentation. You can shoot a subject at different apertures for different DOF effects, or if you’re trying to catch motion in the waves at the beach you can use S mode and tweak the shutter speed to get the desired amount of blur. Locking exposure relieves you from the task of exposure management. If you were in M mode, for every shutter speed you’d want to try you would have to also adjust the aperture appropriately.

On a Nikon you can also enable Auto-ISO, which is a great feature. In A mode, Auto-ISO maintains the lowest possible ISO until the camera’s shutter speed drops to a preset level. At that point, Auto-ISO will not allow the shutter to go any lower, and will raise ISO instead. This is great protection against blur while always using the lowest ISO possible. With a locked exposure you can actually cause three settings to change with one turn of a command dial. If you decide to go from f/4 to f/16, you’ll change your aperture, shutter, and ISO as well...if the shutter needed for f/16 is slower than the “Minimum Shutter Speed” set in Auto-ISO. This really gives you the freedom to just shoot and change your aperture without worrying about blur.

So in constant-light conditions, the idea is to spot-meter a known tone, lock exposure, apply EC, and you’re ready to shoot. But what about changing-light conditions? An example of changing light is when small puffy clouds are rolling across the sky, blocking and exposing the sun. At first thought, auto modes would seem ideal because they’re continuously providing Standard Exposure. But you still have to compensate the exposure, and you can’t lock your exposure. So how do you get consistent, controlled exposure?

The solution is in the fact that with Nikon cameras, spot metering follows the selected focus point. So first you select one spot on your subject to be the “focus” of AF and exposure (the subject’s face, for example.) You evaluate the tone of that spot and apply EC to compensate for the tone. Now it’s time to take some shots. As you photograph your subject and change your framing and composition, you will shift the focus point so that the selected focus point is always over the same spot (the person’s face, in our example.) So you’re “locking” your exposure by virtue of the fact that you’re always setting exposure from the same place. Now, as the clouds roll by and the light changes right before your eyes, your exposure will be consistent shot after shot.

So that’s how you set exposure correctly, the first time, with a Nikon. What I’ve described requires skill and knowledge to implement. But skill and knowledge is what separates a hobbyist/amateur from some Joe at the zoo with his pocket superzoom. Otherwise, your results won’t be any better than Joe’s. So practice and develop those skills!


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