Basic Photography Course Lesson 1 - Sept 29th

Part 1: DSLR Camera, Focal Length & Angle of view, ISO, Focusing, File Types

DSLR camera
DSLR stands for Digital Single Lens Reflex.

Why DSLR camera?
It is the far most popular among the professionals and serious amateurs. It solves many problems associated with the compact camera such as the Parallax Error is corrected with a built-in mirror and prism. Now the viewfinder and the image capturing lens are one in the same when the TTL (Through-the-lens) light passes through the lens is bounced off a mirror and up into the viewfinder, which allowing you to view the object through the same lens that takes the picture. So when you press the shutter release, the mirror is flipped up so that the light can pass on to the image sensor.

Focal Length and Angle of view
Focal length is the distance between the lens and the image sensor when the subject is in focus.

The angle of view is the visible extent of the scene captured by the image sensor, stated as an angle. Wide angle of views capture greater areas, small angles smaller areas. Changing the focal length changes the angle of view. The shorter the focal length (e.g. 18 mm), the wider the angle of view and the greater the area captured. The longer the focal length (e.g. 55 mm), the smaller the angle and the larger the subject appears to be.

Two types of basic lenses
Prime lenses and Zoom lenses

Prime Lenses

Prime lenses have only one focal length.  For example: A standard/normal lens range at 50 mm. It captured images without distortion, which makes the picture looks natural. This lens is generally fast and can have maximum aperture as high as f1.4. This makes it great for low-light situation especially for taking action picture.
Disadvantage: The only way to adjust the image size is by moving closer or further away from the subject.

Zoom Lenses
Zoom lenses can be adjusted to cover a range of focal lengths. Lenses with a wide picture angle are referred to as wide-angle lenses, lenses with a small picture angle as telephoto lenses.

A zoom lens with a focal length of 18–55 mm offers the widest picture angle at 18 mm and the smallest picture angle at 55 mm. If the only lens available is an 18–55 mm zoom lens but you want wider angles—say, for landscape shots—you should buy a lens that offers focal lengths shorter than 18 mm, for example, a 10–24 mm lens. If, on the other hand, you want to photograph at greater distances, you should choose a lens that offers focal lengths longer than 55 mm, for example 55–200 mm. Disadvantages: Heavy, expensive and slower than other lenses.

Lens	Picture angle	Focal length	Area captured	Apparent size
Wide angle	Wide	Short	Large	Small
Telephoto	Small	Long	Small	Large

Wide Angle Lenses – As their name suggests, these lenses enable their users to take shots with a very wide perspective. They are useful for landscapes and for getting in nice and close to subjects still fitting a lot of them in. At the extreme end of the ‘wide angle’ range are ‘fisheye lenses’ which purposely distort your image in a curved way to get more into the shot.
Disadvantage: For close-up picture, easily get distorted images. This lens is meant for landscape.

Telephoto Lenses
Telephoto lenses are used for capturing distance objects like wildlife and spot events.
Disadvantage: When using telephoto lens, it must be held still using a tripod when the shutter is pressed or else the picture will be blurry.

ISO
It is a measurement that indicates a film's sensitive to light. The greater number of ISO the more sensitive it is to light and speed. Base on international standard, the ISO sequence is; 50, 100, 200, 400, 800, 1600, 3200, 6400 and etc. Each step between the numbers effectively doubles the sensitivity of the sensor.
Used low ISO number to produce sharp and better image quality, good shadow detail and greater colour saturation and contrast. For example ISO 50 for landscape and ISO 200 is a good all-round for most purposes. Disadvantages: Not suitable for low light situation and usually tripod is needed when shooting in indoors or flash is needed.
Used high ISO number for low light shooting or when flash is not allowed. Also, ideally used for shooting action photos and moving objects. Disadvantages: It produces grains and noise.

Focusing
Step 1: Without moving the camera, press the shutter release button halfway. Both Focus and Exposure will stay locked. Keep the shutter release button in this halfway position until you are ready to take the picture.
Step 2: Re-frame the picture so it includes the elements you want and excludes anything that is not important to the picture.
Step 3: Pressed the shutter release button completely to take the picture.

File types
There are three basic file format options available when working with a digital camera. Each has its strength and weakness, and each can impact the final image quality.
JPEG
- it's convenience.
- most software support jpeg images.
- small file size.

TIFF
- no compression is applied to the pixels.
- an excellent way to store archival images.
- large file size.

RAW
- it's nota file format.
- developed by individual manufacturer. Example: Cannon - CRW file format and Nikon - NEF file format.
- must convert these files in the computer before you can edit the image.

 Part 2: Shutter Speed, Aperture, Depth of field, Metering System, Prospective and

Polarizing Filters

There are 3 things that affect your image quality in photography; ISO, shutter speed and aperture. All 3 of these things depend on one other factor which is light.

Shutter Speed
What is shutter speed?
In its simple definition, the amount of time that the shutter is open. In film and DSLR cameras, the shutter is the device that opens and closes to control the time that light is allowed to pass through the aperture to the sensor to influence the exposure and action stopping capability.

How does it works?
The shutter speed can usually be changed via the command dials on the camera.

Type of shutter speeds
1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000, 1/4000
Shutter speed is measured in seconds – or in most cases fractions of seconds. The bigger the denominator the faster the speed (i.e. 1/1000 is much faster than 1/30).

Why has variable shutter speed?
- to achieve the desired exposure for different aperture settings
- to affect the way moving subjects appear in resulting photos

How does shutter speed affect a picture?
- fast shutter speed is used to freeze a motion.
- slow shutter speed is used to create a "motion blur".

Note: The ‘rule’ of thumb to use with focal length in non image stabilized situations is to choose a shutter speed with a denominator that is larger than the focal length of the lens. For example if you have a lens that is 50mm 1/60th is probably ok but if you have a 200mm lens you’ll probably want to shoot at around 1/250.

Aperture
What is Aperture?
In its simple definition, the size of the opening in the lens when a picture is taken. The aperture that you set impacts the size of that hole. The larger the hole the more light that gets in – the smaller the hole the less light.

How does it works?
When the control ring is turned the blades move slowly to increase or decrease the size of the aperture vial the command dial on the camera.

Type of aperture measurements
Aperture is measured in f/stops or f/number. For example: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32 and etc. Large aperture = smaller number; Small aperture = bigger number

Why do lenses have variable aperture?
- to vary the amount of light passing through the lens so as to achieve the desired exposure when using different shutter speed.
- to affect the depth of field in the resulting image.

How does aperture affect a picture?
- large aperture like f/2.8 or f/4 have a shallow depth of field.
- small aperture like f/16 or f/22 have a larger depth of field.

Note: Aperture influence the depth of field of a picture.

Depth of Field

What is depth of field?
Depth of Field (DOF) is that amount of your shot that will be in focus. Large depth of field means that most of your image will be in focus. Large aperture reduce DOF, blurring objects behind and in front of the main subject. Small aperture increase DOF, bringing out details in the background and foreground.

Three factors that affect depth of field:
- Aperture
- Focal length
- Focus distance

Note: Short (shallow) field depths are generally used in portraits to blur background details, whereas long field depths in landscape photographs to bring the foreground and background into focus.

Metering System
The goal of the cameras metering system is to create an image that is properly exposed. To get a properly exposed image, besides setting the cameras aperture, shutter speed and ISO, you need to select the metering to analyze the overall brightness of the scene.

Three Kinds of Metering Systems

1. Matrix Meters
Recommended in most situations as this mode works very well for most averagely lit scenes. The camera divides the frame into zones, takes light information from some of them, and calculates a reading from the combination.

2. Center-Weighted Meter
A center-weighted meter measures a much larger area than a spot meter, but focuses most of its attention on the center of the frame. This mode works very well when shooting subjects that fill the frame or are larger in the viewfinder. 

3. Spot Meter
A spot meter uses a very small area of the frame to take a reading from. This is a very useful mode for scenes that are extremely high in contrast and when you have to get the exposure of a small part of the image correct.

Perspective
Perspective in Photography an important composition techniques. It refers to the relationship between the objects in an image. Perspective is about the objects relative position, size, scale and space between them. When you know the principles of perspective in composition you can render the subjects form and shape and give the viewer a sense of space, depth and distance and a sense of scale or character in your image.

Polarizing Filters
A polarising filter looks a lot like a lens from sunglasses. The filter is dark and works by cutting our some of the aspects of light (similarly to sunglasses). As a result less light gets through to your image sensor and you’ll need to either use longer shutter speeds, a larger aperture or to beef up your ISO setting to account for this. The difference that you’ll need to account for is 2 stops.

Advantages of using Polarizing filters
- make blue skies bluer.
- reduce and eliminate glare and reflection.
- reduce haziness in both black & white and colour shots.

Two types of Polarizing filters
- The linear type is used on manual SLR cameras.
- The circular Polarizing filters work well with the focusing and metering systems on automatic SLRs.

Note: Do not use a polarising filter at night. Also, shooting in low light, overcast days or at night with a polarizing filter is not advisable.