Focal Length

Focal Length

The focal length tells us the angle of view—how much of the scene will be captured—and the magnification—how large individual elements will be. The longer the focal length, the narrower the angle of view and the higher the magnification. The shorter the focal length, the wider the angle of view and the lower the magnification.

Standard Lens—FX format approx. 50 – 60mm / DX format approx. 35mm

Standard lenses are popular as they are closest to the angle of view we humans see. These lenses have minimal distortion, which can be flattering to the subject. They tend to use large apertures and allow a lot of light to enter the lens which makes them fast in low light conditions. The large apertures also produce a pleasing out-of-focus effect to the background which concentrates the attention of the viewer on the subject. Standard lenses are the popular choice for a wide range of photography including portraiture, nature and low light situations where the photographer can not use a flash or is looking to capture the scene with available light.

Dave Black

Depth Of Field

Depth of field

depth of field is used to create distance in the image and have one point of the image more clearer than the rest. 
The edges of the image are defined by the point where the loss of sharpness becomes noticeable. Depth of filed is known as the 'Zone of acceptable sharpness'. 

How to control the depth of field

For control of the depth of field you will have to fiddle around with the aperture settings.

For a shallow depth of field you will have to use a larger aperture size. As you can see in this image, the background is in  focus and the subject in the foreground isn't. For me, a shallow depth of field is perfect for landscape photography.  

A small aperture size gives a deep depth of field. the get different types of aperture sizes, it all depends on your camera lens and the elements inside. 



Circle of confusion

The term ‘Circle of Confusion’ is used to define the ‘Depth of Field’.

when taking an image using DoF, we see the 'circle of confusion, which is small circle of sharpness. As the subject in the image starts to walk to the lens, the circle of confusion starts to gets gradually bigger, as the subject is on edge of the DoF, the focus becomes less apparent and the image becomes unfocused and un-sharp. 

 It will become more blurred as the subject continues to walk toward the lens. In other words, outside the DoF we see a larger circle of confusion overlapping with other points nearby creating a blurred area of the image.

Size Matters with the 'Circle of confusion'.

Size is the critical factor. An ‘acceptably sharp’ circle of confusion is defined as one which is unnoticed on an 8 x 10 inch print viewed from one foot away. In practice this works out to about 1/100th of an inch on that print size. Of course a different standard size would apply to different print sizes. Manufactures use these standards to create DoF markers for lenses.

In the modern digital camera we already have a standard preset for the circle of confusion on the sensor. In practice the individual pixel on the sensor makes a convenient focus-point definition. If the circle of confusion exceeds the size of one pixel it will start to affect the surrounding pixels and the sharpness will be lost.

Rule of thirds

The rule of thirds

Rule of thirds is a basic technique in photography.As the grid breaks down the image, you understands that four main image points which gives you points of interest.

Not only does it highlight the four main areas, it also gives you lines to help you take more effective image. Using these points of interest it gives the image more balance and it becomes more pleasing to the eye.

For example, in this photo the point of interests are in the subjects eyes, hair and mouth.
this really draws the audience into the image, also it becomes very intimate because you link direct eye line with the subject.

My own Examples

Aperture

A lens's aperture determines how much light it lets through. More often than not, a wider aperture (lower f-number) is preferable, as it will allow you to take photos indoors and in other situations with little or no natural light.

Wide aperture also allows you to use a faster shutter speed, which is important when photographing fast-moving subjects.

The down-side of having a wide aperture is the cost - lenses with wider apertures can cost significantly more than a normal lens.

Slow Sync Flash photography. 

Slow sync flash photography is a simple but very effective way to create a dramatic image. basically slow sync flash photography is using your flash whilst having a slow shutter speed. This will keep your subject in focus but yet capturing a motion in the image, also it picks up any dark shadows in the background.      

                                   

With a normal image, the shutter is open for a few seconds, so the flash is using most of your exposure but with a long exposure your camera's shutter is open for longer than your flash. 

UNDERSTANDING CAMERA LENSES

All but the simplest cameras contain lenses which are actually comprised of several "lens elements." Each of these elements directs the path of light rays to recreate the image as accurately as possible on the digital sensor. The goal is to minimize aberrations, while still utilizing the fewest and least expensive elements.

Optical aberrations occur when points in the image do not translate back onto single points after passing through the lens — causing image blurring, reduced contrast or misalignment of colors (chromatic aberration). Lenses may also suffer from uneven, radially decreasing image brightness (vignetting) or distortion.

The're many different types of camera lenses but it's important to get the correct for the indented image. 

Standard Lens

Typically you would use a standard lens to get a natural image which is comfortable for the viewers eye.
Standard camera lenses usually have a fixed focal length and wide aperture, giving them excellent performance in low light.

A standard lens is typically used for a wide angle, portrait and landscape shots.  

Macro Lenses

A macro lens are designed for close-ups shot which are suppose to give the viewer impact. The lens are constructed differently to any normal lens so it can give cleaner, more shaper images. 

Macro lenses are used for close-up images of nature, insects but also popular for a extremely detailed images of everyday objects.