8455.38 Utilize the camera systems, controls, and speeds to properly expose an image.
Photography: is the act of capturing light
What is exposure? Exposure is the amount of light that enters the camera and hits the sensor. The more light that hits the sensor the brighter the scene will be. If too muchlight hits the sensor, parts of the image will be “blown out”, this is considered to be over-exposed. A scene that is too dark and the details in the shadows are lost is under-exposed.
Too much light results in an over-exposed photo.
Too little light results in an under exposed photo.
There are 3 basic camera functions that are used to achieve the correct exposure
These are:
ApertureControls the size of the diaphragm in the lens
Shutter SpeedControls how fast the shutter closes to take the picture.
ISOControls the sensitivity of the sensor to light.
This is known as the Exposure Triangle
Aperture Aperture is a little confusing because the larger the number the smaller the size. So besides letting in more or less light, what does the aperture actually do? The more light that comes in at a particular shutter speed, the shallower the depth of field. If you want more depth of field you use a smaller (higher number) aperture setting.
Pro: Larger apertures allow more light in and thus allow shooting in lower light conditions Con: Larger apertures reduce the depth of field which may not be desirable
Shutter The faster the shutter, the less light enters the camera, the slower the shutter the more light will enter the camera. If you are shooting in low light conditions, you may need a slower shutter speed, however, too slow of a shutter and you can introduce blur from the subject moving, accidental camera movement, or both. Sometimes a little blur can help portray movement and action, a sharp bike rider with a blurred background will make the rider look like he/she is moving fast where atack sharp image shows no motion at all and would make the same image look boring. While blurring on other images can ruin the image.
Pro: Fast shutter speeds can freeze action, slow shutter speeds can add a dramatic motion blur. Con: Fast shutter speeds require lots of light, slow shutter speeds are harder to control
ISO Speed As already mentioned, the ISO speed will control the sensitivity of the sensor. The lower the number, the less sensitive. For low light you will need a higher ISO number to make the sensor more sensitive. The downside is that the higher ISO the more digital noise (grainy look) will show up which will degrade the image quality. You currently see high ISO performance as being a major selling point for new DSLR cameras as this allows them to shoot in lower light conditions with less noise. Pro: Higher ISO allows shooting in lower light conditions Con: Higher ISO settings result in more digital noise
2 questions to think about when trying to properly expose an image: