Photography, as has been mentioned before on the blog, is a function of light. There is only a certain amount available in a scene (assuming no artificial light is being used, like a flash or spotlight), and it is up to you the photographer to decide what to do with what is available. The sum of all the light coming in and the way it affects your photograph is called the exposure.
Three elements above will determine the exposure; Shutter Speed, Aperture and ISO. All three are connected, and as a result, changing one will affect the other two.
Briefly, these three elements mean the following:
Shutter Speed: The amount of time the shutter is open.
Aperture: The size of the opening in the lens through which the light comes through.
ISO: A measure of the camera’s sensitivity to light.
The more you start moving away from Automatic or Program modes on your camera, and the more you move into the realm of Shutter Speed or Aperture priority, or even full Manual, the more you control the above three elements yourself. A simple diagram, known as the Exposure Triangle, shows the relationship between the three as follows:
While a combination of the three elements affects exposure primarily, other things are affected as well, eg. the depth of field is affected by a change of aperture or the extent to which motion is frozen and affected by shutter speed.
Using some simple, everyday metaphors can often help understand these concepts. A good one for aperture is to compare the lens, or to be more specific, the hole through which the light comes in, to a window. Opening the window wide will allow more light to come in, while the more you close it, the less light comes in. This analogy can also be used to describe shutter speed: the longer you leave the window open for, the more light can come in.
To work out the right combination of settings, it is important to firstly know which one you are prioritising. It is most likely that you will want to capture a sharp image, which means the highest shutter speed possible in the given conditions. If the light is low, a fast shutter speed will make the photo look darker, so to compensate you will need to make your aperture as wide as possible (which lets more light in), and increase your ISO (the camera’s sensor becomes more sensitive to light). I know it sounds like I’m starting to repeat myself here, but bear with me.
We haven’t looked at ISO properly yet, but briefly, changing it alters the amount of ‘noise’ in your picture. Have a look at the following two crops of a photo of the scar-nosed Majingilane:
The ‘grain’ of the photo is a lot more visible in the second photo than the first. It is one of the drawbacks of boosting your ISO; you start seeing this ‘noise’ creeping in. Certain cameras eg. the Canon 5D perform better in low light, and the noise will not be as noticeable, but it is a tradeoff you will have to make sometimes, as the higher ISO will allow you to get a faster shutter speed, and a sharper image as a result. A grainy yet sharp image is far better than a non-grainy, blurred one!
Here’s an example:
Say it’s getting towards evening and you are shooting on Aperture priority. Your tracker finds a leopard and she’s lying on a fallen log in the evening light. To the human eye it may seem like the light is beautiful and there is more than enough for a photograph. Your camera sees differently, and even though your aperture is as wide open as possible, you are only managing a shutter speed of 1/40th of a second. If your camera is dead steady and the leopard is not moving this can still be ok, but what would you do to achieve a higher shutter speed? You’d raise your ISO to increase the camera’s sensitivity to light. Note: Raising the ISO does NOT simply mean lifting the camera higher up, as has been seen before!
It takes a while to master exposing your photos correctly. It is largely a matter of trial and error when you start out, but thanks to the advent of digital photography, you can snap away and not worry about wasting money on expensive film. I would certainly recommend moving away from the Automatic and Program settings on your camera. Once you’ve taken the responsibility for that first step, you’re away! As I’ve mentioned before, you are smarter than the little microchip on your camera, so what the camera is telling you, you can or can’t do and what is actually possible are often two very different things.,
The above photo of one of the Majingilane roaring into the night would have probably been impossible had I been using an automatic setting. The camera would have read the scene as being far too dark and probably exploded. Ok that might not have happened. But it was only by switching to Manual mode and controlling the settings to expose for the very small bit of light in the photo (provided by a spotlight off to the side) that I was able to capture the outline of the lion.
This photo of the Tamboti female in the Maxabene was one in which I wanted to draw attention to her face. In order to do so I kept my depth of field narrow by opening my aperture wide. Now remember a wide aperture lets in a lot of light (remember the window!) so my shutter speed was hopefully going to be nice and high to freeze her movement. She was down in a riverbed however, walking in the shade, so to ensure a high shutter speed I upped my ISO to 800.
Fiddle around with the various settings to find what works for you. If you have been using Auto or Program modes, I would certainly not recommend moving to full Manual straight away, rather Shutter speed or Aperture priority. It is also important to properly familiarise yourself with your camera and its various buttons and dials, as an amazing photo opportunity may present itself without warning, and if it takes you five minutes to get the right settings, the moment will have passed!
Hope this helps. Feel free to add comments below…
Written and Photographed by James Tyrrell