Cambridge in Colour

Lenses

There are many different variations of lenses that can be used with a variety of cameras. Although most lenses look the same, they are all very different. I myself have various lenses such as 50mm prime, 75-300 and 85mm prime. The 2 different types of lenses are prime/fixed and zoom. These names are based on the focal length of the lens. Personally, I favor specific lenses depending on the task in hand. If I don't require a zoom in the image, prime lenses are perfect for many reasons. The main reasons why I usually prefer a prime lens is because of the depth of field. The short depth of field enables the focus to be very specific and can more often than not, also make the image look more professional. 

"The focal length of a lens determines its angle of view, and thus also how much the subject will be magnified for a given photographic position. Wide angle lenses have short focal lengths, while telephoto lenses have longer corresponding focal lengths." 

"The focal length of a lens may also have a significant impact on how easy it is to achieve a sharp handheld photograph. Longer focal lengths require shorter exposure times to minimize blurring caused by shaky hands. Think of this as if one were trying to hold a laser pointer steady; when shining this pointer at a nearby object its bright spot ordinarily jumps around less than for objects farther away."

Zoom VS Prime 

"A zoom lens is one where the photographer can vary the focal length within a pre-defined range, whereas this cannot be changed with a "prime" or fixed focal length lens. The primary advantage of a zoom lens is that it is easier to achieve a variety of compositions or perspectives (since lens changes are not necessary). This advantage is often critical for dynamic subject matter, such as in photojournalism and children's photography."

"The primary advantages of prime lenses are in cost, weight and speed. An inexpensive prime lens can generally provide as good (or better) image quality as a high-end zoom lens. Additionally, if only a small fraction of the focal length range is necessary for a zoom lens, then a prime lens with a similar focal length will be significantly smaller and lighter. Finally, the best prime lenses almost always offer better light-gathering ability (larger maximum aperture) than the fastest zoom lenses — often critical for low-light sports/theater photography, and when a shallow depth of field is necessary."

http://www.cambridgeincolour.com/tutorials/camera-lenses.htm

Exposure

http://www.cambridgeincolour.com/tutorials/camera-exposure.htm

One of the most important things while taking photographs or shooting film, is the lighting. Lighting can make or break your work so it's very important to get it right from the start. The exposure determines how light or dark the image will be - this is determined by 3 different camera settings: aperture, ISO and shutter speed. 

Aperture: controls the area over which light can enter your camera. 

Shutter Speed: controls the duration of the exposure.

ISO speed: controls the sensitivity of your camera's sensor to a given amount of light. 

You can use many combinations of the above three settings to achieve the same exposure. The key however, is knowing which trade-offs to make, since each setting also influences other image properties. For example, aperture affects the depth of field, shutter speed affects the motion blur and ISO speed affects the image noise.

Aperture

A camera's aperture setting controls the area over which light can pass through your camera lens. It is specified in terms of an 'f-stop'. As the f-stop decreases, the area increases - the bigger the f-stop, the smaller the hole in which the light can pass through. 

Aperture Setting	Relative Light	Example Shutter Speed
f/22	1X	16 seconds
f/16	2X	8 seconds
f/11	4X	4 seconds
f/8.0	8X	2 seconds
f/5.6	16X	1 second
f/4.0	32X	1/2 second
f/2.8	64X	1/4 second
f/2.0	128X	1/8 second
f/1.4	256X	1/15 second

I am going to use my own images as examples of wide aperture and narrow aperture. The wider the aperture, the shallower the depth of field - meaning the less in focus. The narrower the aperture, the larger the depth of field - meaning the more in focus. 

Narrow Aperture: 

Wide Aperture: 

Shutter Speed
A camera's shutter speed determines when the camera sensor will be open or closed to incoming light from the camera lens. The shutter speed specifically refers to how long this light is permitted to enter the camera. Shutter speed's influence on exposure is perhaps the simplest of the three camera settings: it correlates exactly 1:1 with the amount of light entering the camera. For example, when the exposure time doubles, the amount of light entering the camera doubles. 

Shutter Speed	Typical Examples
1 - 30+ seconds	Specialty night and low-light photos on a tripod
2 - 1/2 second	To add a silky look to flowing water Landscape photos on a tripod for enhanced depth of field
1/2 to 1/30 second	To add motion blur to the background of a moving subject Carefully taken hand-held photos with stabilization
1/50 - 1/100 second	Typical hand-held photos without substantial zoom
1/250 - 1/500 second	To freeze everyday sports/action subject movement Hand-held photos with substantial zoom (telephoto lens)
1/1000 - 1/4000 second	To freeze extremely fast, up-close subject motion

Shutter speed is a powerful tool for freezing or exaggerating the appearance of motion. The slower the shutter speed, the more motion blur and the faster the shutter speed, the less motion blur and faster it captures the subject. I am going to use my own images to show examples of these. 

Slow shutter speed:

Fast shutter speed:

ISO Speed
The ISO speed determines how sensitive the camera it to incoming light. Similar to shutter speed, it also correlates 1:1 with how much the exposure increases or decreases. However, unlike aperture and shutter speed, the lower ISO speed is almost always desirable because the higher ISO speeds dramatically increase image noise. 

Low ISO speed:    High ISO Speed: