Back to Basics #5- White balance
White balance is a process that your camera carries out in order to ensure the whites that are seen with they eye appear as white as possible in the final digital image. On my Nikon D3200 I have multiple white balance settings such as: Auto, cloudy, cool-white fluorescent, direct sunlight, flash, incandescent and shade. The auto function allows the camera to decide white preset to use, however this can sometimes leave blue or green casts on the photo when taken. For this reason the manual settings are often used to decide on the right white balance for a particular object or scenario. Here of some examples of what happens if you change the white balance settings:
As you can see some of the above pictures have a blue cast on this which was avoidable by using other, more appropriate settings. The auto mode worked quite well here, selecting direct sunlight as its white balance which I agree with.
It is also possible to manually set your white balance using a grey card, often used by professional portrait photographers.
Back to basics #4- The ISO
The ISO is the last of the 3 settings which help determine the exposure. So far we have spoken about the shutter speed and the aperture, the ISO helps adjust these settings. The ISO is the sensitivity of the sensor and is measured in numbers. For example 100, 200, 400, 800, 1600, 3200 and 6400 are avaliable on my Nikon DSLR. The ISO may need to be raised if a shutter speed isn’t fast enough because of lack of light. By increasing the ISO the amount of available light is picked up more by the sensor allowing a usable shutter speed to be used.
There is one issue with increasing the ISO is noise. As the sensor becomes more sensitive to light, digital noise can be found on an image. Modern DSLR’s now have some great noise reduction capabilities which make high ISOs usable. Noise can also be removed by some photo editing software.
So thats it for the ISO, come back next week for an article on white balance.
Back to basics #3- The aperture
Within a lens you have aperture blades which control how much light gets into the lens and reaches the sensor, this is called the aperture. This setting called the aperture and is controlled with an F/number. The larger the F/number the more the aperture blades are going to be closed, therefore less light will reach the sensor and on the other hand the smaller the F/number the more the aperture blades will be open so more light will reach the sensor. For example F/8 is going to let in much more light that F/22 This aperture setting is essential to the exposure.
The aperture you use to take an image also affects how much of the photo is in focus, also known as the depth of field. The depth of field can be useful to change depending on the desired effect. During a landscape you might need a deep depth of field to keep everything in focus however portraits might want only a shallow depth of field to blur out the background. The blurred background is known as ‘bokeh.’ The quality of the bokeh can be very soft depending on the lens you use. The lower F/number allows you to have a shallow depth of field, resulting in more of the photo being out of focus and higher F/numbers give a deep depth of field making most of the photo in focus. The two photos in this article use a deep depth of field. This photo uses a shallow depth of field, leaving only some of the track in focus.
When you buy a lens the smallest F/number will be written on the front. The average 18-55mm kit lens is 4-5.6. There is a range of smallest apertures on most zoom lenses because as you zoom the smallest F/number possible changes. With prime lenses you will have one smallest aperture. For example Nikons 50mm is available in F/1.8 or F/1.4 models, the 1.4 being the more expensive options.
Back to Basics #2- Shutter speed
Within the camera you have multiple components. One of the most important of these is the shutter. The shutter opens when the picture is being taken and shuts to cut off the light. In film photography the shutter was key as it would allow the film to be exposed to light for a set amount of time. This is the same in digital cameras but they have a sensor rather than film. The length of time the shutter is open for is determined by a setting called the shutter speed.
This is often found in fractions of seconds and whole numbers. The fastest shutter speed available on my Nikon D3200 is 1/4000th second. This would expose the sensor to light for a very sort amount of time, useful on a very sunny, bright day. The slowest shutter speed is 30 seconds, leaving lots of light to get to the sensor. This would be used at night when it is very dark. There is also one more option available if you scroll all the way to the 30 second end and go on a bit. It is called ‘bulb mode.’ Bulb mode allows you to choose any length of time for the shutter to be open for. It is activated by the first click of the shutter button and turned off by a second. For this setting I use a remote trigger to prevent camera shake. Click here to see the remote I use.
Shutter speed is also key when you are trying to capture movement. Using shutter speeds like 1/2500th second on a waterfall will freeze the action. If a slow shutter speed of 1/5th second is used on a waterfall it will begin to blur out the water in long streaks as it falls. This can be nice to the eye. People often used 5 second or slower shutter speeds on rivers to give the water a glassy, smoothed out effect. This isn’t always possible during the day though because too much light gets to the sensor, leaving an under-exposed image. This can be prevented by using an ND-filter. (One item on my Christmas list!) The ND-filter prevents so much light entering the lens which allows those slower shutter speeds to be used in broad daylight. These can be brought in multiple ‘stops’. A 10 stop will lower the amount of light by 10 stops, perfect for a long shutter speed. With a 2 stop you can step your shutter speed down by 2 stops so a shutter speed of 1/500th second will be able to become a 1/125th second shutter.
Slow shutter speeds can also be used in light painting. Click here to see an example of light painting. The faster shutter speeds are useful for freezing movement so I used them here, here,here and here.
Above is an example of a 1/50th second shutter speed, fast enough to capture the ripples in the water
Above is taken on the same day in exactly the same place as the other, however this was taken with a 3 second shutter speed. This long exposure allowed the water to be smoothed out and given a glassy look.
Back to basics #1- Exposure
This is now the first in my back to basics series where I will cover all the key aspects to get you started in photography. The first part I will cover is the settings, this one being on the exposure which is determined by the ISO, Shutter speed, Aperture and white balance.
This first one as I said is on the exposure, the most fundamental part to learn when getting into photography. The exposure is basically how much light is reaching the sensor during the capture of the photograph. This is a very important thing to get right as if you under expose your image then it will be really dark but if you over expose it you’ll end up with a white, washed out image.
To make sure that your exposure is correct you can look at your cameras built in light meter. This is just a line that the pointer moves either way until your setting allow a what it believes to be a well exposed image. This however can be incorrect so a bit of experimentation is required.
I hope you’ve enjoyed the first post in my back to basics series. Come back next week to learn about the first setting which determines the exposure, the shutter speed!