Measuring the Intensity of Light

In order to shoot an image with the correct exposure, you have to know the correct value of the intensity of light. Photographers use light meters to measure the intensity of the reflective light in a scene. Digital cameras have built-in light meters that are very sophisticated and incredibly accurate. However, their accuracy is subjective. The recommended aperture and shutter values are determined by how light falls in the scene and by how the light meter is set.

The Color Temperature of Light

Color temperature is a term used to describe the color of light. Every light source has a color temperature. However, color temperature refers to the color value of the light rather than its heat value. Light’s color temperature is measured in units called Kelvin (K). This temperature scale measures the relative intensity of red to blue light.

How White Balance Establishes Color Temperature

When you take a photograph with a digital camera, the color temperature of the scene is not taken into account until the image is processed by the camera’s processor. The camera refers to its white balance setting when it processes the image.

The Human Eye’s Subjective View of Color

Elements of a good photo include composition, color, and brightness. One of your jobs as a photographer is to capture the colors you see as intentionally as possible. Whether you intend to show the color exactly as you see it or you want to enhance the color by adjusting the color temperature, it is your job to understand your choices and intentionally compose your picture.

Reducing Digital Noise

Digital noise is the polka-dot effect in images with long exposures or images shot at high ISO settings in low-light situations. The effect is most noticeable in images shot in low-light situations. Many consider digital noise to be a synonym for film grain. Although the causes are the same, the effects are quite different. Some film photographers purposely shoot images with enhanced grain for artistic effect.

Minimizing Red-Eye in Your Photos

Red-eye is the phenomenon where people have glowing red eyes in photographs. This is caused by the close proximity of the flash (especially built-in flash) to the camera lens, which causes light from the subject to be reflected directly back at the camera.

Reducing Camera Shake

Camera shake is caused by a combination of the photographer’s hand movements or inability to keep the camera still, slow shutter speed, and long focal length. Camera shake results in a blurred image. The focal length of the lens, combined with a slow shutter speed, creates a situation in which the shutter speed is too slow to freeze the image before the camera moves significantly.

Why Shoot RAW Files?

There are many reasons to capture images as RAW files rather than JPEG files. However, it’s important to note that RAW image files require additional work to achieve the color balance you’re looking for, whereas JPEG files are color-balanced by the camera for you. JPEG files are also smaller than RAW image files, requiring less storagespace.

Understanding RAW, JPEG, and TIFF

It’s important to understand the differences between image file types. RAW, JPEG, and TIFF file types are described below.

RAW : A camera’s RAW file is an uninterpreted, bit-for-bit digital image recorded by the camera when the image is captured. Along with the pixels in the image, the RAW file also contains data about how the image was shot, such as the time of day, the exposure settings, and the camera and lens type.

Memory Card

After the digital image sensor has captured the image, the camera employs a series of processes to optimize the image. Many of these processes are based on camera settings established by the photographer prior to taking the shot, such as the ISO setting. After image processing, the camera stores the digital information in a file.

RESOLUTION and ISO

Resolution : A camera’s resolution capability is measured in megapixels. This measurement is based on the number of millions of pixels of image information that can be captured by the light-sensitive elements on the digital image sensor. Thus, a 15 megapixel camera is capable of capturing 15 million pixels of information.

Digital Image Sensor

When the reflective light from the photographed subject passes through the lens and aperture, the image is captured by the digital image sensor. A digital image sensor is the computer chip inside the camera that consists of millions of individual elements capable of capturing light. The light-sensitive elements transform light energy to voltage values based on the intensity of the light.

Using Reciprocity to Compose Your Image

You can adjust the aperture setting and shutter speed to create several different correctly exposed images. The relationship between the aperture and shutter is known as reciprocity. Reciprocity gives the photographer control over the depth of field of the Image, which controls the area of the image that remains in focus. This is the easiest way to control what part of the image you want the viewer to pay attention to.

For example, opening the fens aperture by one stop and decreasing the shutter speed by one stop results in the same exposure. Closing the aperture by one stop and increasing the shutter speed by one stop achieves the same exposure as well. Therefor, f4 at 1/90 of second is equal to f5.6 at 1/45 of a second. The reason is that the camera's aperture setting and shutter speed combine to create the correct exposure of an image.

SHUTTER and SHUTTER SPEED

Shutter

The shutter is a complicated mechanism that precisely controls the duration of time that light passing through the lens remains in contact with the digital image sensor. The camera’s shutter is activated by the shutter release button. Prior to the digital age, the shutter remained closed to prevent the film from being exposed.