Digital Single-lens Reflex Camera

Digital Single Lens-Reflex Camera, are digital cameras combining the parts of a single-lens reflex camera and a digital camera back, replacing the photographic film. The reflex design scheme is the primary difference between a DSLR and other digital cameras. In the reflex design scheme, light travels through a single lens and a mirror is used to reflect a portion of that light through the view finder - hence the name Single Lens Reflex. The image that is seen through the viewfinder is also the image that is captured by the camera's sensor.

DSLR Camera Functions

• Auto Mode. This mode pretty much does exactly what it says on the dial. In Auto Mode, the camera will set everything for you -- from your aperture and shutter speed right through to your white balance and ISO. It will also automatically fire your pop-up flash (if you camera has one), when needed. This is a good mode to use while you familiarize yourself with your camera, and it is particularly useful if you need to photograph something quickly, when you don't have time to set the camera up manually. Auto mode is sometimes represented by a green box on the camera dial.

• Program Mode (P). Program Mode is a semi-automatic mode. The camera still controls most of the functions, but you are able to control ISO, white balance, and flash. For example, in Program Mode, you could prevent the flash from firing automatically and instead raise the ISO to compensate for low light conditions, such as when you don't want the flash to wash out the subjects' features for an indoor photo. Program Mode can really add to your creativity, and it's great for beginners to start exploring the camera's features.

• Aperture Priority Mode (A or AV). In Aperture Priority Mode, you have control over setting the aperture (or f-stop). This means that you can control both the amount of light that comes through the lens and the depth of field. This mode is particularly useful if you're concerned about having control over the amount of the image that is in focus (i.e. depth of field), and are photographing a stationary image that won't be affected by shutter speed.

• Shutter Priority Mode (S or TV). When trying to freeze fast moving objects, shutter priority mode is your friend! It's also ideal for times when you want to use long exposures. You'll have control over the shutter speed, and the camera will set the appropriate aperture for you. Shutter Priority Mode is especially useful with sport and wildlife photography.

• Manual Mode (M). This is the mode that pro photographers use most of the time, as it allows complete control over all the camera's functions. Manual mode means that you can adjust all functions to suit lighting conditions and other factors. However, using manual mode requires a good understanding of the relationships between different functions -- in particular of the relationship between shutter speed and aperture.

Aperture

An aperture is a hole or opening that light can travel through, so specifically, the aperture is an opening that determines the cone angle of rays that travel through. The aperture stop of a photographic lens can be adjusted to control the amount of light reaching the film or image sensor. In combination with variation of shutter speed, the aperture size will regulate the film's or image sensor's degree of exposure to light. Typically a fast shutter will require a larger aperture to ensure sufficient light exposure, and a slow shutter will require a smaller aperture to avoid excessive exposure.

Diagram of decreasing aperture sizes (increasing f-numbers) for "full stop" increments (factor of two aperture area per stop)

Typical ranges of apertures used in photography are about f/2.8–f/22 or f/2–f/16, covering 6 stops, which may be divided into wide, middle, and narrow of 2 stops each, roughly (using round numbers) f/2–f/4, f/4–f/8, and f/8–f/16 or (for a slower lens)f/2.8–f/5.6, f/5.6–f/11, and f/11–f/22. These are not sharp divisions, and ranges for specific lenses vary.

ISO

In digital Photography ISO measures the sensitivity of the image sensor. The same principles apply as in film photography - the lower the number the less sensitive your camera is going to be to light, and the finer the grain.

Higher ISO settings are generally used in darker situations to get faster shutter speeds (for example an indoor sports event when you want to freeze the action in lower light) - however the cost is noisier shots.

When choosing ISO settings you should ask yourself:

1. Light - Is the subject well lit?

2. Grain - Do I want a grainy shot or one without noise?

3.Tripod - Am I using a tripod?

4. Moving subject - Is the subject moving or stationary?

If there is plenty of light, I want little grain, I'm using a tripod and my subject is stationary, it is probably good to use a low ISO rating.

Situations needing a higher ISO include:

Indoor Sports Events - Where your subject is moving fast yet you may have limited light available

Concerts - Also low in light and often 'no-flash' zones

Art Galleries, Churches - Many Galleries have rules against using a flash and of course being indoors are not well lit.

Birthday PArties - Blowing out the candles in a dark room can give you a nice moody shot which would be ruined by a bright flash, Increasing ISO can help capture the scene.

Shutter Speed

In photography, shutter speed or exposure time is the effective length of time a camera's shutter is open. 

The total exposure time, or duration of light reaching the film or image sensor.

For fast moving objects you will want a fast shutter speed, the slower the speed, the more bury the moving subject matter will be, having faster shutter speeds is important for this fact. 

In early days of photography, available shutter speeds were not standardized, though a typical sequence might have been 1/10 s, 1/25 s, 1/50 s, 1/100 s, 1/200 s and 1/500 s. Following the adoption of a standardized way of representing aperture so that each major step exactly doubled or halved the amount of light entering the camera (f/2.8, f/4, f/5.6,f/8, f/11, f/16, etc.), a standardized 2:1 scale was adopted for shutter speed so that opening one aperture stop and reducing the shutter speed by one step resulted in the identical exposure. The agreed standards for shutter speeds are:

• 1/1000 s
• 1/500 s
• 1/250 s
• 1/125 s
• 1/60 s
• 1/30 s
• 1/15 s
• 1/8 s
• 1/4 s
• 1/2 s
• 1 s