EXPOSURE

In photography, exposure is a critical element that determines what is actually recorded on a camera's image sensor. There are three adjustable elements that control the exposure - ISO, Aperture, and Shutter Speed. So what is the perfect exposure?

Well technically, every scene we shoot has a dynamic range. The dynamic range is the difference between the brightest part of that scene and the darkest part. Our sensor or film has a dynamic range too (technically it's exposure latitude - but we're picking hairs).

What we hope to accomplish is to capture that dynamic range of the scene into our image. So that the brightest part of the image (say the sky) is not blown out and devoid of detail, and the darkest part (shadows or foreground dark areas) are not lost into noise.

Sometimes the dynamic range of a scene can exceed the dynamic range of our camera, so we have to make a choice of what part we want to have the best exposure. Usually with digital it is best to have the brightest areas in good exposure and not blown out. But it can depend on the situation.

If we are shooting a portrait, we want our subject to be perfectly exposed even if that mean that another part of the image my not be. Some times that is a sacrifice we have to make, if we cannot change the conditions of the shoot nor have the option of supplementing the lighting.

This first image is underexposed. There is good light on the rocks but the sky and clouds are missing detail because of overexposure.so does the last image. The image is too overexposed, too many light.

THE EXPOSURE TRIANGLE IN PRACTICE

Now that we have a basic understanding of the three elements of exposure. Let's examine how we might use them and see the interaction between them.

Let's say we wanted to shoot an automobile race and we want to stop the action. It's a bright sunny day so we are going to use ISO100. We want to stop the action of the car going by us very fast, so we choose 1/1000 of a second shutter speed - but with that shutter speed according to our meter in our camera that would give us an aperture of 5.6.

So we know from what we learned about aperture, that may give us a shallow depth of field and there are other race cars we want to be within reasonable focus. So how could we fix this? We can't change our shutter speed, so we turn to the other part of our trio; ISO.

If we move our ISO up two stops to 400, we can then make out aperture two stops smaller and get the depth of field we need plus the shutter speed we need to stop the action.

We still have our camera set the same, but while we are at the races we spot a beautiful classic car in the parking lot. We want to isolate it from the ugly background so we decide that we now need a shallow depth of field. So we open our lens up to f4 on our 200mm lens.

This gives us great separation and DOF but that drives our shutter speed up to 1/6000th of a second! This would be OK - we are hand holding our camera, not stopping any action - but we want this to be a great shot worthy of a very large print.

So why don't we lower our ISO two steps to ISO 100, That brings our shutter speed down two stops to a still fast 1/1600 but because we lowered our ISO we will have much less noise in our image to be printed large.

BALANCE IN PHOTOGRAPHY

Balance is one of the least-discussed principles of good composition, but it is perhaps the most important. Photographers, consciously or not, make an important decision for every image: should the composition be balanced or imbalanced? To some degree, every photograph in existence has elements of both balance and imbalance, which makes this topic crucial for photographers looking to improve the strength of their images at the most fundamental level.

What is Balance photography?

Balance in photography is observed when an image has subject areas that look balanced throughout the composition. It is achieved by shifting the frame and juxtaposing subjects within it so objects, tones, and colors are of equal visual weight. An image is balanced when subject areas command a viewer’s attention equally.

There are two main techniques of balance: formal and informal. However, there are also other kinds of formal and informal techniques that photographers have been practicing to balance out lightness and heaviness, varying shapes, and even meanings behind a composition.

SYMMETRICAL BALANCE

Symmetrical balance refers to balance that is achieved by arranging elements on either side of the center of a composition in an equally weighted manner. Symmetrical balance can be thought of as 50/50 balance or like a mirror image. In other words, the image would look the same on either side of the center.

ASYMMETRICAL BALANCE

Also known as informal balance, it is the most common compositional technique taught in photography and art workshops. Since it requires intentionally placing your subject off center, it’s more difficult to achieve but gets easier with daily practice.

The rule of thirds puts asymmetrical balance to your advantage, as it suggests that the center of interest lies along the intersecting lines of an image that is divided vertically and horizontally by four lines. Other ways to create asymmetrical balance within the composition is by balancing out your main subject with another, less important subject that contrasts with the former in terms of size, color, or general appearance.

In the photograph above, the viewer’s eye is initially drawn to the stones in the foreground, but is soon dragged to the mountains in the background. While the stones, being darker, hold a lot of weight, the brightness of the mountain in combination with the area it covers holds an equal weight. The range of highlights and shadows in the rest of the composition only reinforce this balance. Without the rocks, there would be too much negative space in the foreground. Without the mountain, there would be too much negative space in the background. Even though this photograph is not symmetrical, it is still equally balanced.

Few types of balance below is a type of asymmetrical balance;

TONAL BALANCE

While we have touched on tones before, tonal balance can be seen most clearly in photographs that are nothing but black, whites, and grays. Balance can be seen in terms of contrast between the light and dark areas of an image.

COLOUR BALANCE

We’ve seen how different tones hold different weights, but did you know that different colors hold different weights as well? Think about it this way: if you were looking at an image that was half bright red and half muted yellow, which color would your eyes automatically drift to? For most of us, the answer is the red. Brighter colors are ‘heavier’ than neutral colors, which is why a pop of color within a photograph can easily balance out a scene that would otherwise be too heavy on one side.

CONCEPTIONAL BALANCE 

If you’re just getting used to using balance in your own compositions, take time to perfect the above types of balance before branching out to the more philosophical type. It’s important to note that for a photograph to be conceptually balanced, it should also be either asymmetrically or symmetrically balanced as well.

In the photograph above, you can see how the composition is beautifully tonally balanced. The deep shadows are perfectly countered by the bright shadows, and the darker industrial scene in the background balances the large, bright branch in the foreground. The balance doesn’t stop there, however. The branch, which is no longer alive, speaks to the effect of industrialization on the environment. The juxtaposition of industrialization and nature is only one of many ways that you can play around with conceptual balance in your own images

RULE OF THIRD

The rule of thirds is a powerful compositional technique for making photos more interesting and dynamic. It's also perhaps one of the most well known. Using the 'Rule of Thirds' is not something that you have to do, but it goes a long way to improving your photography.
The rule of thirds states than an image is most pleasing when its subjects or regions are composed along imaginary lines which divide the image into thirds — both vertically and horizontally:

The rule of thirds is applied by aligning a subject with the guide lines and their intersection points, placing the horizon on the top or bottom line, or allowing linear features in the image to 
flow from section to section.

How to apply rule of third

1- Check your camera to be sure it has a grid

2- With this grid in mind the ‘rule of thirds’ now identifies four important parts of the image that you should consider placing points of interest in as you frame your image.

The theory is that if you place points of interest in the intersections or along the lines that your photo becomes more balanced and will enable a viewer of the image to interact with it more naturally. Studies have shown that when viewing images that people’s eyes usually go to one of the intersection points most naturally rather than the center of the shot – using the rule of thirds works with this natural way of viewing an image rather than working against it.

3- With the 'visual' of the rule of thirds, take a photograph. Be sure the subject of your image is at the crosshatch whenever possible. Even if it isn't at the crosshatch, but at the location of a third; left, right, top, bottom. In this screenshot, you see that the eyes are at the top third.

SHUTTER SPEED

WHAT IS CAMERA SHUTTER?
WHAT IS SHUTTER SPEED?
HOW SHUTTER SPEED IS MEASURED?
WHERE AND HOW TO FIND SHUTTER SPEED? 

Shutter speed is one of the three pillars of photography, the other two being ISO and Aperture. Shutter speed is where the other side of the magic happens- it is responsible for creating dramatic effects by either freezing action or blurring motion.

WHAT IS CAMERA SHUTTER?

Well, camera shuter is a curtain in front of the camera sensor that stays closed until the camera fires. When the camera fires, the shutter opens and fully exposes the camera sensor to the light that passes through the lens aperture. After the sensor is done collecting the light, The shutter closes immedicately, stopping the light from hitting the sensor. The button that fires the camera is also called shutter or shutter button because it triggers the shutter to open and close.

WHAT IS SHUTTER SPEED?

Shutter speed is also known as exposure time stands for the length of time a camera shutter is open to expose light into the camera sensor. If the shutter speed is fast, it can help to freeze action completely. If the shutter speed is slow, it can create an effect called motion blur" where moving objects appear blurred along the direction of the motion. This effect is used quite a bit in advertisement of cars and motorbikes.

How shutter speed is measured?

Shutter speeds are typically measured in fractions of a second, when they are under a second. For example 1/4 means a quarter of a second, while 1/250 means one two-hundred-and-fiftieth of a second or four milliseconds. Most modern DSLRs can handle shutter speeds of up to 1/4000th of a second, while some can handle much higher speeds of 1/8000th of a second and faster. The longest shutter speed on most DSLRs is typically 30 seconds (without using external remote triggers).

How to find the shutter speed?

go to the setting the camera to “Manual” mode, where you set both shutter speed and aperture manually. Look through the viewfinder, it should also be the number on the bottom left side of the screen. On most DSLRs, you will not see the shutter speed as a fraction of a second – it will typically be a regular number. When the shutter speed is slower than or equals to one second, you will see something like 1″ or 5″ (the ” sign indicates a full second).

If you still can’t find the shutter speed, set your camera to “Aperture Priority” mode, then look into the viewfinder and point at a really dark area. Remember the numbers in the display, then switch to a very bright area and see what number changes. The number that changes is your shutter speed.

APERTURE.

APERTURE

What is aperture?
How does it work?
What is the effect?

Aperture refers to the opening of a lens's diaphragm through which light passes. It is calibrated in f/stops and is generally written as numbers such as 1.4,2,2.8,4,5.6,8,11 and 16. The lower f/stops give more exposure because they represent the larger apertures, while the higher f/stops give less exposure because they represent smaller apertures.

So basically on the camera, where we can find aperture is at ;

That way, your aperture opens up and let more light into the camera sensor and increases your shuter speed. For your 18-105mm lens, The aperture varies between f/3.5 and f/5.6, so try to keep it in that range. If you are still getting blurry images, try increasing your ISO to a larger number such as 1S0 800. All lenses have a maximum aperture, and all NIKKOR lenses list the widest possible aperture on the lens barrel. Some zoom lenses will detail something like f/3.5-5.6 on the lens barrel or 1:3.5-5.6 (below right). These numbers, the 3.5 and the 5.6, are referring to the maximum aperture or widest opening the lens can achieve for each end of the zoom range. Some higher end lenses can maintain the largest aperture throughout the entire zoom range, so only one number is detailed (below left).

HOW APERTURE AFFECT DEPTH OF 

FIELD

Depth of field is defined as " the zone of acceptable sharpness in front of and behind the subject on which the lens is focused" Simply put on how sharp and blurry is the area behind your subject. Here's the equation.

The lower the f/stop- the larger the opening in the lens- the less depth of field- the blurrier the background.

The higher the f/stop- the smaller the opening in the lens- the greater the depth of field and the sharper the background.

How the aperture affects shutter speed the f/stop also affects shutter speed. Using a low f/stop means more light is entering the lens and therefore the shutter doesn't need to stay open as long to make a correct exposure which translate into a faster shutter speed. Again, the reverse is true, using a high f/stop means that less light is entering the lens and therefore the shutter will need to stay open a little longer which translate into a slower shutter speed