Manual Exposure Mode (M) - Nikon D5100 Experience Manual

Nikon D5100 Experience
A full stop difference means the amount of light that reaches the sensor is either doubled or
halved. For example, if your aperture is set to f/5.6, changing it to f/4 will double the amount of
light reaching the sensor, and changing it from f/5.6 to f/8 will halve the amount of light that hits
the sensor. The area of the aperture opening was doubled or halved. Since the area of an
aperture opening is nearly circular, doubling or halving that area involves an equation with Pi,
thus resulting in the seemingly random steps from f/2.8 to f/4 to f/5.6, etc. With shutter speeds,
changing from, say, 1/125 to 1/250 halves the amount of light, and 1/125 to 1/60 doubles the
amount of light hitting the sensor. The time that the shutter was open was doubled or halved.
With ISO settings, changing from, say, 400 to 800 doubles the sensitivity, and going from 400 to
200 halves it.
The reality is you don't need to know all this math to take a successful photo. When you have
your camera set on A or S, it figures much of this stuff out for you. You will inevitably learn
more about it through experience and as you follow up on why your camera did a certain
something or why an image looks as it does when you used certain settings. But you don't need
to know how a watch works to tell time, and you don't need to immerse yourself in exposure
values to start out with a digital SLR. So while some of this other stuff might be complicated, I
will try to avoid stops and EV so as not to make it even worse.

Manual Exposure Mode (M)

Many people seem to believe that the epitome of camera skill is demonstrated by the use of
Manual Exposure Mode (M). Old-school photographers might scoff at those who need to rely on
fancy exposure metering systems and nostalgically brag about how they can approach a scene,
read the light, and set their exposure manually. But the truth is, digital SLR photography just
isn't done like that. There is no need to turn yourself into a human light meter and spend years
honing your ability to detect subtle changes in lighting levels. There is no need to consult the
camera's Exposure Indicator and set both shutter speed and aperture for every shot when the
camera can automatically adjust one of those settings for you. Aperture-Priority Auto Mode and
Shutter-Priority Auto Mode are perfectly acceptable and common ways to use your camera and
its intelligent built-in exposure metering system that Nikon spent years developing.
But there are times you may wish to use Manual Exposure Mode. For example, if you are taking
several photos to stitch together into a panorama, you want them all to be taken with the same
exposure so that the lighting is consistent across the entire scene. Or if you are working in a
studio setting and the lighting will remain consistent, you can set the exposure once and then not
worry about it. Or in any other situation where the lighting or your desired exposure will remain
consistent such as an indoor performance or sunny day portrait session where the lighting does
not change.
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