Camera Basics : An Overview – Part I
The camera consists of a lens that gathers and focuses light, an iris that controls how much light enters the camera, and a shutter that controls how long the light is allowed to contact the film. When you open the shutter, light from your subject is allowed to contact the film. The film has a coating on it that contains silver halide crystals, which are extremely sensitive to light. When exposed, the light causes a chemical reaction, changing the salts into black silver. Naturally, the more light allowed in, the more crystals that are affected. The lighter areas (such as the sky or sun) cause more silver to form and thus are darker. That’s why the end result is called a negative, because it is the opposite of what you normally see. The development process reverses this, putting the colors back where they are normally.
There are literally hundreds of different kinds of cameras and each one is designed for a specific application. Talking about camera basics, we’ll take a look at one of the more common cameras, the 35mm SLR. The 35mm is a compromise between simplicity and quality. They use negatives about 1″x 1 1/2″, big enough to render decent quality, page size prints. The SLR refers to Single Lens Reflex. It is a very simple design. A mirror reflects light from a single lens to the viewfinder. The lens is usually removable, allowing you to use special purpose lenses.
Some people do things one way, and others do it a different way. The same is true with photography, so many different types of cameras have emerged. Some find the 35mm too big, so smaller “pocket cameras” were made. In addition to being very small themselves, they also use very small film cartridges. They’re useful for making prints up to the size of a postcard. There are also instant cameras, that eject a print intermediately after taking your picture. It usually takes a few minutes for the image to develop fully, but is still far quicker than taking it to a photo-lab.
For high quality prints, there are a variety of larger cameras with correspondingly larger film sizes. One of the most common uses 120 rollfilm, which produces negatives 2 1/4″ wide. Though bulkier, these cameras are still hand-held and render high quality prints even when the negatives are blown up to many times their original size. With faster shutter speeds, it isn’t quite as crucial to hold yourself steady, but with slow shutter speed, even slight movements can make a picture blurry. The easiest way to counteract this is to use a tripod, but sometimes you can even just brace yourself.
Camera Basics : Focusing
In order to have sharp images, you need to insure your camera is focusing correctly. Though the size of the aperture lens can affect the size of the area that is in focus, the main factor is how close to the lens your subject is. Most cameras have a simple focusing ring that moves the lens forward and backward, changing its distance from the film and affecting the focus.
Some of the simplest cameras have a ring with distances in meters and feet marked on it. You focus it by selecting the appropriate distance. There are much more accurate methods of focusing, such as split-image. The most common split-image focuser has two semi-circular prisms that split images down the middle. You adjust it until the two halves match up and focus properly. Another version of it is one composed of many tiny micro-prisms that have the same basic effect, but break it up into many hundreds of pieces, similar to a kaleidoscope.
Range-finder focusing creates a double image of the unfocused subject. It is very easy and clear to tell whether the image is correctly focused. This makes it particularly useful for focusing Single Lens Reflex cameras in dim light, when it is often difficult to get one to focus properly. The area that will be in sharp focus is relatively narrow at close range, the background and surrounding area will be somewhat out of focus. The farther away your subject is, the wider your field of focus will be.
Camera Basics : The Shutter
When firing a gun, you don’t jerk the trigger because it throws your aim off, you gently squeeze it so it stays on target. The same basic principle applies to your camera. When you get everything centered and just right, carefully press your shutter so everything stays the way you want it. The shutter controls your film’s exposure time, so it is very important you pick a speed appropriate to what you are doing. Most of them are set by a numbered dial. The numbers stand for fractions of a second, so 100 means 1/100. Most SLR cameras go up to 1/1000, but you can find some of them that go as high as 1/4000 second.
The faster the speed, the less time there is for any movement on the part of the subject or camera to have an effect, so for sharp pictures, the faster the better. The normal workhorse speed is about 1/125, which is fast enough to take shots of everything but rapid motion. Close-ups usually require higher speeds, in excess of 1/250, and so do “active” pictures, like children playing. Low-light conditions often require longer exposure times in order to get a decent amount of light. This does increase the risk of blurring, so usually a tripod or other support should be used to insure a stable image.