What is a simple definition of photography exposure? Before this simple question is answered; a simple process how the camera can capture the object into a good photograph needs to be understood. The camera can capture the object into a photograph image when there is sufficient light coming into the camera sensor.
The photo below is an example of correct photography exposure; the object receives sufficient light from the flash light so the camera sensor can also receives sufficient light to capture the image of the object with the correct photography exposure.
When the camera cannot receive sufficient light from the object; the other word is when there is not sufficient light illuminates the objects; the camera will capture the objects with less light.
As the result the image produced by the camera will be dark grey and this condition is called UE – Under Exposure. An example of photography exposure which results UE is shown in the photo below. The photo below was intentionally made to produce an underexposure example with the condition of low light; no flash; no exposure compensation.
A proper exposure result
When the camera receives excessive light from the objects; the other word is when there is much light received by the objects; the camera will capture the objects with excessive light. Unless the exposure compensation is controlled; the result of the image will be very bright and this condition is called OE – Over Exposure. Photography exposure which results an OE can be shown in the photo below.
An under exposure photo - not sufficent light to illuminate the object
To produce a wonderful photograph, you need to pay attention to the photography exposure techniques. Creating a wonderful color tone to the pictures, can be done by optimizing the amount of light received by the camera sensor. See also the photo light – how to increase the quality
An over exposure (OE) photo result
There are three elements that need to be considered when you play around with photography exposure; it is “The exposure Triangle”
Each of the three elements of the triangle relates to the light and how it enters and interacts with the camera sensor. If we compare light to water, we can consider a glass of water as the amount of light needed to expose a photo correctly. Then, the relationships are established as indicated by the figure below which is a basic photography exposure technique regarding the aperture and shutter speed.
Triangle Exposure
If you allow a large amount of water to flow, you can fill the glass in a short period of time. If you allow a small amount of water to flow, it will take longer to fill the glass. To understand photography exposure in this example, the amount of water flowing from the tap corresponds to the aperture, and the time needed to fill the glass corresponds to the shutter speed.
What about ISO?
The third component of photography exposure is ISO. ISO identifies sensor sensitivity to light; the camera is able to amplify the light received by the sensor. Photography exposure with lower ISO setting; requires longer time to expose to the light. And the detail quality result of the image is higher.
While photography exposure with higher ISO setting; requires faster time to expose to the light. Higher ISO increases noise and the detail quality of the image reduced as the data received by the sensor is amplified.
Which ISO setting?
To get a good photography exposure when you photograph the objects with minimum light; use higher ISO setting in the manual camera setting; say 800 until 1600. Since the camera amplifies the light in relation to higher ISO; the consequence is the noise increased.
At daytime or when the light source is abundant; use lower ISO setting say 100 to obtain higher detail quality of the image.
Aperture
Aperture is very essential in photography exposure. When you open the aperture widely; it will produce a shallow depth of field (DOF). The focus is sharp only to the shallow area. It is commonly applied on the model photography or to create an explicit object.
AV=4.0 and ISO speed = 400
When you open small aperture; it will produce a photo with a wide depth of field; a wide detail area. It is commonly applied on landscape photography which wide detail area needed to cover wide landscape view.
The landscape photo below was captured using aperture f/22 and ISO speed is 100; and the shutter speed is 1/50 s. You can see that the wide detail of the photo covers the whole frame. See also photography composition guidelines.
Small aperture for wide area detail
Diaphragm and shutter speed
A proper combination of diaphragm and shutter speed will produce a proper photography exposure. The camera adjusts the exposure by using the shutter speed and aperture parameters. Small aperture will produce picture with a wide depth of field, a wide detail area. High shutter speed will be able to freeze the fast moving objects.
Fast speed to freeze the moment
Shutter speed and aperture have interrelation each other. If the aperture is small then the camera will receive few amount of light; the shutter speed will be slow. Contrary, when the aperture is wide; the camera receive more light; the shutter speed will be increased.
To evoke a soft effect of a river stream, select smaller aperture so a lower shutter speed will be achieved. In the picture below, the aperture is set to f/22 and shutter speed is 1/6. Be careful if you want to use small aperture to soften the river stream, assure the models to stay put.
Low speed to soften the water stream
The aperture and shutter speed can be represented as follows:
Representation of shutter speed and aperture
The difference between values at successive stages is called a stop. Some cameras can be set in 1/2 or 1/3-stop increments. It is convenient if you become familiar with these values. They appear complex, but if you take a closer look, you will find that the values change according to specific rules.
All digital cameras combine the exposures system and controlling them automatically. However, a sophisticated metering system will not be able to exactly understand what the camera see or what the photographer wants. Your action needed to adjust and control the camera manually to produce the proper photography exposure – the great and natural picture.
Photography exposure in Extreme light
The camera will work harder when targeting extreme level of bright objects. On film camera, this condition is called latitude exposure, while in digital camera this condition is called dynamic range. In a sunny day it is impossible to achieve the photography exposure that records all detail of the shadow without resulting excessive light on the targeted subject and so is vice versa.
Generally digital camera has the same exposure latitude value as film camera does. So the dynamic range value of digital camera can be assumed to be 4EV. It means that you still can see or correct the shadow detail that is 2EV darker than the mid-tone in your camera. So what will you do if the object has the brightness higher than 4EV? See also Tricking the light that will discuss more detail about the dynamic range.
Photography exposure in Mid-tone
Mid-tone concept is very essential in photography exposure. It describes the area of the subject that is in the middle of the tone value. This is the area of the subject that you would like to emerge in the picture. The problem is how bright or dark a mid-tone is?
All digital cameras has classical metering system problem. It is therefore digital camera needs to maximize the exposure by working at the average standard of “grey” tone that is exactly at 18% grey. It is therefore you need to control the exposure about on the level of 18% brightness. See also background issues that will discuss more detail about this classical metering system.
Photography exposure in metering pattern
Light meter in the camera might not be able to capture that different subject has different inherent brightness level. But at least the camera can differentiate the light with high contrast different. By default; digital camera uses ‘multi pattern’ metering mode that measures several points on the targeted object. After detecting the main subject’s position, brightness, background, front lighting and back lighting etc, the camera sets the proper exposure. But some photographer tends to prefer a simple ‘center weighted’ metering that weighted at the center and then averaged for the entire scene. While spot metering weighted at the center covering about 3.5% of viewfinder area.
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