LESSON 2 - Camera Tutorial, Part 1
(DSLR vs Point-and-Shoot, Lenses and Focal Length)
Article by Stephen J. Kristof
© 2010, all rights reserved
Have you ever considered what makes your camera "tick"? In this section, you'll learn about the main parts of a camera, how they work together and what role they play in producing an image.
Much of the learning that is to follow will apply to basic point-and-shoot digital cameras, but as the concepts become more complex (such as, for example, making manual adjustments to exposure), owners of Digital Single Lens Reflex (D-SLR or DSLR) cameras may better relate to some of more advanced
information. Regardless of what you own, though, all readers of FreePhotoCourse.com will make gains in both progress and application.
Now, read on and enjoy this college-level learning...for free!
(DSLR vs Point-and-Shoot, Lenses and Focal Length)
Article by Stephen J. Kristof
© 2010, all rights reserved
Have you ever considered what makes your camera "tick"? In this section, you'll learn about the main parts of a camera, how they work together and what role they play in producing an image.
Much of the learning that is to follow will apply to basic point-and-shoot digital cameras, but as the concepts become more complex (such as, for example, making manual adjustments to exposure), owners of Digital Single Lens Reflex (D-SLR or DSLR) cameras may better relate to some of more advanced
information. Regardless of what you own, though, all readers of FreePhotoCourse.com will make gains in both progress and application.
Now, read on and enjoy this college-level learning...for free!
2.1.1 The Lens
What one element is the most important to photography? Of course, it's LIGHT and without it there would be no photography at all.
The camera’s lens allows light to pass into the otherwise light-proof ‘box’ which is the body of the camera. The lens captures, concentrates, focuses and projects an image onto the light-sensitive, image-sensing digital "chip" inside the camera. This chip (also called a CMOS or CCD) converts the light image into electronic data that can then be processed and transformed back into a visible image.
The lens is one of the most important parts of the camera, as it is responsible for the clarity of your images. Take a look at the front of your camera. How wide is your lens? This is a very important consideration in terms of the flexibility a photographer has and with regard to the clarity of the images that a camera can produce. In general, the wider lens is, the higher quality its photos will be (and the more expensive it will be as well).
Why is this? It's because the wider a lens is, the more light it will allow into the camera. More light equates to improved clarity, better edge definition and truer colors. White light is comprised of all of the colors in the spectrum, so more light means more color. Look at photos that you've taken that should be very colorful, yet look drab, muddy and colorless. Chances are that when you took that photo, the environment along with your subject matter were too dark, your flash was not on and/or your lens is too small to let much light through.
If the lens on your camera is smaller than a half inch across it is not likely very efficient at delivering a lot of light. In practical terms, this means that you are restricted to composing photos in conditions of high rather than low light. It also means that colors may be rendered with less saturation than in real life. Further, the small lens may make it more difficult to photograph moving objects clearly, because the reduced light requires slower rather than the fast shutter speeds necessary to freeze motion.
The camera’s lens allows light to pass into the otherwise light-proof ‘box’ which is the body of the camera. The lens captures, concentrates, focuses and projects an image onto the light-sensitive, image-sensing digital "chip" inside the camera. This chip (also called a CMOS or CCD) converts the light image into electronic data that can then be processed and transformed back into a visible image.
The lens is one of the most important parts of the camera, as it is responsible for the clarity of your images. Take a look at the front of your camera. How wide is your lens? This is a very important consideration in terms of the flexibility a photographer has and with regard to the clarity of the images that a camera can produce. In general, the wider lens is, the higher quality its photos will be (and the more expensive it will be as well).
Why is this? It's because the wider a lens is, the more light it will allow into the camera. More light equates to improved clarity, better edge definition and truer colors. White light is comprised of all of the colors in the spectrum, so more light means more color. Look at photos that you've taken that should be very colorful, yet look drab, muddy and colorless. Chances are that when you took that photo, the environment along with your subject matter were too dark, your flash was not on and/or your lens is too small to let much light through.
If the lens on your camera is smaller than a half inch across it is not likely very efficient at delivering a lot of light. In practical terms, this means that you are restricted to composing photos in conditions of high rather than low light. It also means that colors may be rendered with less saturation than in real life. Further, the small lens may make it more difficult to photograph moving objects clearly, because the reduced light requires slower rather than the fast shutter speeds necessary to freeze motion.
2.1.2 Zoom Lenses and Focal Length
If you have a DSLR, you will choose the power of magnification and the width of view by purchasing zoom lenses or, less commonly, telephoto lenses with a fixed (single) magnification power. As the photographer becomes more knowledgeable and interested in different types of photography, he or she may also invest in special application optics, such as wide angle lenses, dedicated macro lenses, and even professional level super-zoom lenses.
The magnification power of lenses for DSLR cameras is noted in millimeters. This is also referred to as the "Focal Length". Have you ever heard the term "long lens"? This refers to a zoom or telephoto lens that has a long focal length. It also looks longer than a lens that provides less magnification.
The lower the number, the wider the view and, conversely, the higher the number, the more magnified the view. A 28 mm lens will provide for a very wide angle, while a 300 mm lens will bring an image in approximately 10 times closer than it actually is. Lenses with a focal length of 50-55 mm provide the same field of view as your unaided eye - meaning that objects appear to be at the same distance through the lens as they do in real life. As focal length increases, so does magnification and the relative size of objects. As it decreases, things conversely look farther away and smaller. Super wide-angle lenses can be as short as 10mm.
Some lenses are so big (and expensive!) that they need a special mount so that the tripod is supporting the lens (with camera attached) rather than the other way around! For example, the Canon EF 600mm F4/L IS USM telephoto lens is a profesisonal-level lens with a VERY wide opening, called an aperture, which is unusual for a lens of this magnification. You've likely seen many of these lenses attached to cameras on the sidelines of pro football games. Sports magazine, newpaper and website photographers, as well as nature photog's that shoot wildlife from a distance, need to capture bright, clear and close images and the use of a professional-level high zoom lens is an absolute necessity.
These pro's need to show an athlete's expressions as they make the big play. The particular lens mentioned above (and other pro-level super-telephoto lenses as well) retails out at just over $8,000. But why is it so expensive when most zoom or telephoto lenses in this magnification category retail for under $300? The reason is that huge opening in the lens. As noted above, in the average lens, as the magnification increases, this opening decreases, meaning that there is a tradeoff. The picture will get progressively darker with progressive magnification; if your subject is moving quickly, the lack of light is not a good thing, because low light prevents the photographer from using a high shutter speed that would be required to freeze motion. The fine optics in this particular lens nullify the light vs length tradeoff; that's why the pro's use these types of lenses - the only remaining tradeoff is the cost of the lens!
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What's the difference between a digital point-'n-shoot (PNS) camera and a DSLR? One very obvious difference is the size. DSLR cams are much bigger than their PNS cousins. That's because there's more going on inside the DSLR, in terms of mechanical movement. The PNS has virtually no mechanical movement with the exception, perhaps, of a servo motor that slides the internal zoom lens forward or backward as the user presses the "T-W" toggle to zoom in or out.
A DSLR camera boasts a complex shutter system that uses a physical process consisting of a moving mirror, sliding curtain and/or metal leaves, and other moving parts that allow light into the camera for a predetermined and precisely accurate amount of time. The DSLR always has manual metering, manual focus abilities and manual exposure controls. As well, DSLR cameras use removable/interchangeable lenses for different purposes, as discussed in the paragraph about Focal Length below. |
 a basic POS (Point & Shoot) camera  a DSLR (Digital Single Lens Reflex) camera  interchangeable DSLR lenses |
Consider the two images below. The photograph on the left showing the helicopter was captured using a zoom lens with a focal length of 600mm. This expensive "wide aperture" lens allowed the photographer to bring the chopper FAR closer than it was in reality. At about 1,500 feet (457 metres) from the lens, it's easy to see what an efficient job this lens accomplishes. Best of all, the wide aperture in this expensive lens allows for a bright image. The photographer needed to use an extremely fast shutter speed in order to freeze the very fast motion of the rotor and the aircraft itself. Had the lens been a standard lens with a smaller aperture, insufficient light would be available to use such a high shutter speed. (If you need some help understanding these terms, read Lesson 3 on DSLR Technique (Exposure Control) on this website for a very indepth explanation and training.)
The image of the peacock to the bottom right was shot with a standard 70-300mm zoom lens. The magnification was at full focal length; 300mm. See the difference? This image is darker, less clear and "grainier" than the one on the left. As well, there appears to be some barrel distortion near the edges of the photo; a hallmark of a cheaper lens.
 600mm focal length with wide aperture of f-4 |
 300mm focal length with smaller aperture of f-8.5 |
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