Welcome to the next video in our camera basics series.
In our previous videos I’ve explained Aperture and Shutter Speed - click on the card above
in either corner to watch if you haven’t already.
In this video I will explain how ISO works and how to use it.
This video is part 3 of 4 videos that will eventually explain how the exposure triangle
works so make sure you subscribe to keep up to date.
We have also joined the latest trend on YouTube short videos so don’t forget to check those
out as well for some quick photography tips and tricks.
What is ISO?
ISO is one of the three elements that makes up the exposure triangle.
It’s essentially another tool which helps you to control the light and therefore helps
you to take a well exposed image in whatever condition you’re shooting in.
Aperture and shutter speed both control how much light hits your sensor, but ISO determines
how sensitive your camera sensor or film is to the light.
But what does ISO mean?
As usual, this term dates back to film photography.
It doesn’t stand for something specific to photography.
It stands for International Standards Organisation.
They set various standards across the world, including “Film Speed”.
Film Speed is how sensitive a film is to light.
And now, it’s how sensitive a camera sensor is to light.
It’s measured in numbers using a logarithmic scale.
This means, every time the ISO number doubles, the film or sensor sensitivity increases by
one stop.
When we talk about “stops” in photography, we’re talking about either doubling or halving
light.
An increase of “one stop” means you double the light being taken in, whether this is
by changing your aperture or changing your ISO – or changing your shutter speed.
In simple terms, the bigger the ISO number, the more sensitive your camera sensor is to
light.
Now, when to change ISO...
You’ve already learned about Aperture and Shutter speed in our other videos...
Well, I hope you have.
Youshould now know how to use them creatively or functionally.
ISO is the final piece of the puzzle.
In film photography, you’d choose a film with a higher ISO depending on where you would
be shooting.
If you were taking photographs in bright sunlight ISO 100 would be absolutely fine.
Using something higher might result in your photos being overexposed.
But using ISO 100 in a dimly lit restaurant would mean your images would likely be underexposed.
Or you’d have to use a longer shutter speed to let more light in… but then you risk
having blurry images.
In digital cameras, it’s much easier because you’re not stuck with one ISO for 36 shots.
You can change it as and when you need to – or let the camera change it by using the
auto-ISO setting.
You’re mainly going to change the ISO if you have no natural light or if artificial
light is out of your control.
However…
changing ISO can have a negative impact on your images.
When you increase it, you also increase the digital “noise” in your images.
Noise is the graininess in the image, and this increases the higher the ISO value.
If you’ve ever taken a photo with your mobile phone in low light, you’ve probably noticed
that it looks grainy.
Now, this is the ‘noise’ I’m taking about.
This is because your phone has increased the ISO to compensate for poor lighting.
Different sensors have different points at which noise will start to be noticeable.
On an older digital camera, this is evident at ISO 3200, but on a modern high-end sensor
you’re unlikely to see visible noise at this level.
Low vs high ISO noise visibility: As you can see in this example, the lower
ISO value has no noise, and the higher ISO value has a lot of noise as well as ‘graininess
and blotchy’ colours.
Therefore, you should avoid high ISOs whenever possible, unless conditions require you to
use them.
Here is another example of a range of ISO values in a darker setting to show that in
certain situations you must increase your ISO value to retain more information within
your image.
When to use low ISO: You should try and stick to your camera’s
lowest native value and control the light with your aperture and shutter speed if possible.
This will give the cleanest image.
If you are in a situation where you can’t do that for example, you need a faster shutter
speed to capture some action then this is where you would increase your ISO value.
It’s handy to know how far you can push your ISO value on your camera before noise
is introduced in your image.
You can test this very easily at home.
As you can see here, I’m testing the Sony A7III to see what’s the highest value I
can reach so I know for future reference.
Some cameras are better in low light, and some aren’t, so it all depends on the specific
model you have.
Now, when to increase ISO: Increase your ISO when you can’t control
the light in other ways.
So, the first example: You don’t want to change your shutter speed.
You’re shooting in very low light, for example at a gig.
Changing the shutter speed would mean the musicians aren’t in focus.
Increasing your aperture would affect the depth of field.
Increase your ISO instead.
The second example: You’re shooting a landscape handheld with
a dark and moody sky.
You don’t want to change the aperture as you want the whole scene in focus.
You don’t want to change the shutter speed as your image might not be sharp, but your
image is coming out too dark.
Increase the ISO until you achieve the perfect exposure.
Now the third example: You’re photographing a family gathering
indoors.
You just want the camera to decide on shutter speed and aperture so you can enjoy yourself
and not think too much about the settings.
You don’t want to distract people using a flash and the lighting is dim.
Increase your ISO as required to make sure your shots are well exposed.
As you can see, it’s all about balancing Aperture, Shutter Speed and ISO settings depending
on your desired outcome and the environment you’re working in.
The basic points for understanding ISO are: The higher the ISO, the more sensitive your
camera becomes to light.
This can help you take well exposed images in difficult lighting situations.
The higher the ISO, the more noise you’ll see in your images.
This can reduce image quality.
So now you know about Aperture, Shutter Speed and ISO!
We’ll cover the whole Exposure Triangle together in its own video very soon, but what
other basics of photography do you want to learn?
Let us know in the comments below.
And please don’t forget to like and subscribeto our channel!
And again, don’t forget o check out our YouTube short videos for some quick photography
tips and tricks.
So until next time I will see you all soon.