beginner photography

Exposure triangle

Episode 3


The Exposure Triangle relates to the three fundamental concepts in photography - Aperture, Shutter Speed, and ISO.

In this series, I will take you through all three of these aspects, plus more, and break down each one simply - giving you the stepping stones to explore and research each in more depth as you gain confidence and experience with your camera.


ISO


ISO is the last piece of the puzzle in the exposure triangle.


What is ISO?

Technically speaking, it refers to the sensitivity of your camera’s sensor to light. The term began back in the days of film photography, where it referenced the film's sensitivity. However, in digital cameras, ISO controls how sensitive the image sensor is to the light that enters the lens.

ISO is represented by numbers like 100, 200, 400, 800, and beyond. A lower ISO number means the sensor is less sensitive to light, while a higher ISO number makes the sensor more sensitive.

My basic explanation to it, especially now in the digital age, think of ISO as a way to digitally lightening your images.

Once you have chosen your subject and have set the aperture and shutter speed to your required result, the image may still be too dark, or under exposed; and this is an issue. So ISO is the last effort to lighten the image to gain the correct exposure.


A lot of photographers will tell you that keeping to an ISO of 100, the lowest (and 'darkest') setting available in ISO, is best, as dialling up your ISO can present some issues, as we will discuss shortly, however, this can also be a personal choice depending on the creative look you are going for.



NOISE

The main downside of increasing your ISO is the introduction of what is called "noise", or grain, into your image. This noise looks like a sandy filter over your image, and is generally more noticeable in smooth areas of your image, like a soft background. Noise is especially noticeable with very high ISO settings (1600 and up).

The higher the ISO, the more grainy your photo may appear, which can potentially reduce the overall quality; 'quality' meaning sharpness in this context.

I have found throughout my journey in photography, that a lot of photographers seem to demonise a high ISO, and are very quick to tell you to keep it as low as possible. However, every camera is different and can handle different amounts of light, so test out your camera in low light conditions to see what sort of noise appears at the different ISO levels and gain an understanding of what your camera can handle. Make sure to evaluate these images on your desktop computer to get a close up view of the noise, as the LCD screen on the back of the camera doesn't show much. Once you have determined your max ISO, some camera's have a setting in which you can choose to set a max ISO amount the camera can go to; saving you if you are in any setting other than manual mode (eg. aperture priority), as the camera will not go about your set ISO setting.



LIGHTING CONDITIONS

Daylight/Outdoor Shooting: When there’s plenty of light, stick to a low ISO (like 100 or 200). This will give you a cleaner, crisper image with no noise.

Indoors/Low Light: In dimmer conditions, increase your ISO to around 800 or 1600, depending on how dark it is. This will brighten your image, but may increase the noise.

Night Photography: If you’re shooting in near-total darkness or at night, you’ll often need a high ISO (3200 and above). This will help capture more light, but you may see a lot of noise.



Conclusion

ISO is short and sweet. Really, it is just an electronic way to increase your exposure to get the shot. But the main thing to remember about a high ISO is that there may be noise present in your images. So really, if raising the ISO and getting noise in the image is the only option for getting the shot - which would you rather?



what's next?

Get out there with your camera and explore! Use low apertures to soften backgrounds, use slow shutter speeds to create motion blur.

Go out and have fun!

Come back and see me to explore more about photography!


Low ISO


With a low ISO, you can see in this image of a background that the transitions are soft. Again, this can be a stylistic choice.

High iso


This image of a high ISO background clearly shows the noise. The colours and edges are not smooth. I included the models face in this one to demonstrate what effect noise can have on the face - to me it doesn't look too bad, but that is open to interpretation, depending on what you like.