Hi, everybody. Welcome to Episode 26 of the Photography Explained podcast. In this episode, what does ISO stand for in photography? Now it might sound dull, but it’s important, so bear with me.
I’m your host, Rick, and each week I will try to explain one photographic thing to you in plain English in less than 10 minutes without the irrelevant details. My aim is to explain things in just enough detail to help us with our photography, and no more.
What does ISO stand for in photography? This is my answer.
ISO in photography refers to the sensitivity of your camera sensor to light. The higher the ISO number, the more sensitive your sensor is to light (in theory). The lower the ISO number, the less sensitive your sensor is to light (in theory). A low ISO setting is generally better than a high ISO setting. ISO is one of the three elements of the exposure triangle, the others being aperture and shutter.
And if that doesn’t get me that Google snippet I don’t know what will!
You can listen to the episode here
Or keep on reading. Or do both. Entirely up to you!
So what does ISO actually stand for?
Wow. Yet another thing that if we were starting again with photography, we wouldn’t have this term. ISO is International Standards Organisation, an organisation that exists to standardise things across the world.
So absolutely no criticism of this organisation for doing this because it’s dull, very important stuff it is that they do. So fair play to them.
So what does it actually mean?
ISO – well let’s not worry about that. If we go back to the film photography days ISO was a thing. There were other film sensitivity scales, called DIN and ASA.
In there is the origin of ISO in photography.
ISO in photography is used to relate to the sensitivity of camera film to light. Well, it still does. But this has now been applied to the sensitivity of the camera sensor to light.
Exactly the same but rather than physical film there is something electronic and clever called a sensor.
So what do these all stand for?
Well, I don’t really care to be honest with you, ISO is the thing that we need to know about.
So what do the numbers in the ISO range mean?
This is the important bit.
Okay, you can have an ISO of 100 which is a low ISO, and an ISO of 12,800 which is a high ISO.
The ISO Scale
There is something called an ISO scale. And these are the main numbers in the ISO scale. Now this is as dull as the aperture scale and the shutter speed range. But there is at least an amount, well, no, there’s some logic to this scale.
Let me tell you what the numbers are. And then I’ll tell you what I mean.
This is it – wait for it.
- 100, 200, 400, 800, 1600, 3200, 6400, 12800 25,600.
Beyond the scale
Now there are lower ISOs than 100 – I used to have ISO50 on an older Canon SLR, and there is probably ISO 25. There might even be 12.
And there are higher ISOs than 12,800, such as 25,600, 51,200 and onwards into a digital snowstorm.
I guess you would have 102,400. And then you’d have a 204,800 and something 400,000 and something but this is getting ridiculous, isn’t it?
What do I use?
The normal ISO range that I use, is 100 to 400.
That’s it. That’s all I do most of the time.
I’ve only got three real options.
But what do these numbers actually mean?
Okay, you have probably noticed that these numbers, double 100, 200, 400, etc. Each doubling of the ISO is also the doubling of the sensitivity of the sensor to light.
An ISO of 200 makes the camera sensor twice as sensitive to light as 100 is. And this change is known as one stop.
Post podcast episode note – the actual sensitivity of the sensor does not change – that is fixed. The brightness of the image changes. I have had this wrong for many years, so good to finally correct that. It still amounts to the same though.
Stops?
Yes, stops.
Each of these doublings or progressions of the ISO scale is a full stop. Now moving from 100 to 200 is a doubling of the sensitivity to light (well actually how bright the image is).
And it’s the exact equivalent of a one-stop adjustment of the aperture or shutter speed.
ISO, Aperture and shutter
If you change the aperture by one stop, erm let’s use actual numbers here.
If you go from F5.6 to F8, you are having the amount of light which is a one stop adjustment. The same applies to shutter speed, I went through the shutter speed range in a previous post.
These three things are related to each other, but don’t worry – I will explain this lot in more detail in the next episode.
Between you and I, I’m sort of dreading coming out with the definitive explanation of the exposure triangle, because I always mess it up. And that’s why I’ve tried to do it bit by bit. So I’ve done aperture, shutter and ISO separately.
Let’s move on.
What is the best ISO?
Well, the lower the number, the higher the quality in very broad general terms. And the higher the number, the higher the chance of you getting noise in the photo, which will impact on the quality of the photo.
So there isn’t a definitive best number.
The lower the ISO you can use the better.
What’s noise?
Noise is just stuff that makes the photo look grainy and not sharp and messy and horrible. The only good thing about noise is that people outside of photography don’t know what it is. So they might be able to see it, but they wouldn’t know it was a noisy photo unless it was that digital snowstorm I mentioned earlier.
Noisy V blurry photo
There is one thing that people who are not into photography do know though, and that is what a blurry photo is.
Let me explain.
If you’re taking a photograph handheld, you have two options.
One is to use a shutter speed that is so slow that you only get a blurry photo.
The other is to increase the ISO allowing you to use a faster shutter speed and get a sharp photo.
What do you do?
You’re better off getting a sharp noisy photo than a blurry noise-free photo.
Trust me about that – you can do things with noise in Photoshop and Lightroom. And with other plugins which are available, which I don’t really use.
If you take a photo and it’s blurry, it’s blurry forever, there’s nothing you can do about it.
And that’s the facts. So use the lowest ISO you can and if you need to increase ISO to get a sharp photo, do so. That is all you need to know about ISO I promise you.
Tripods again
Take your photos on a tripod and you can just leave it on the lowest ISO possible and not worry about this. I take 95% of the photos for my commercial work on a tripod.
I have left my ISO on my Canon 6D on 100 for, well I can’t remember how long. Every now and then when I’m in poor light and I’m shooting handheld (which isn’t often) I might go for a higher ISO of 200 or 400. 800 even. And every now and then 1600.
But I don’t remember the last time I used ISO800 or 1600 apart from when I was just mucking around and experimenting.
Let’s not overthink this.
The lowest ISO you can use to get a sharp photo the better.
Okay, how do ISO, aperture, and shutter speed relate?
We’ll come back to this in the next episode.
Is there anything else I want to say?
I’m not sure why I put that on my list for this episode. Yes, I have notes (would you believe?)
- Low ISO is good.
- Blurry photo is bad.
(Yes I really said that!)
Okay, so what’s next in the next episode? I am going to explain the exposure triangle again.
Okay. And now we’re on to the thank you section.
Thank you for listening. I hope you enjoyed this episode. If you did, please leave a nice review and rating wherever you get your podcasts from and please subscribe so you don’t miss an episode. And if you could tell one person about my podcast who might be interested you will have my thanks forever.
Check out my website rickmcevoyphotography.com where you can find out all about me and my architectural photography, my construction photography, my landscape photography, and my travel photography. You can also find out how you can get in touch to ask me a question which I will gladly explain to you on one of the future episodes of the Photography Explained Podcast.
You can also see a list of the things that I’ve got down to explain. You can actually go through an episode list as well and you can play old episodes if you want to.
Next episode
What Is The Exposure Triangle? (Revisited)
So yeah, that’s me done. The first episode of 2021.
Let’s hope 2021 is better than 2020
This episode was brought to you by the power of sheer optimism. I’ve been Rick McEvoy. Thanks again for listening and giving me 11 minutes of your valuable time. And I’ll see you in the next episode.
Cheers from me, Rick
OK – that was the podcast episode.
Want to know more?
Head over to the Start page on the Photography Explained Podcast website to find out more.
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Finally, yes this paragraph is all about me – check out my Rick McEvoy Photography website to find out more about me and my architectural, construction, real estate and travel photography work. I also write about general photography stuff, all in plain English without the irrelevant detail.
Thank you
Thanks for listening to my podcast (if you did) and reading this blog post (which I assume you have done as you are reading this).
Cheers from me Rick
