A Basic Guide to Choosing Your ISO Setting

A Basic Guide to Choosing Your ISO Setting

One feature of our digital cameras that evolves with every single generation of sensors and processors is ISO performance. With astronomical ISO numbers now available, just how high should you push your ISO?

I spoke in my article last week about how most modern cameras have exceptionally good ISO performance and that for most applications, ISO isn’t really something you even need to worry about. Today we’ll take a deeper look into that topic by starting with the positive and negative outcomes of raising your ISO sensitivity. Then, we’ll move on to how far you should raise your ISO. Finally, we’ll take a look at ways of reducing some of the detrimental effects of high ISO on your images. 

Pros and Cons of Raising Your ISO

Raising your ISO effectively makes your sensor more sensitive to the light coming in through the lens. Exactly how this is done varies from sensor to sensor, but there are some common effects that boosting ISO has on the resulting image. 

A sensor with a higher ISO setting will record a given scene more brightly than one with a lower ISO setting. Thus by raising the ISO sensitivity, you are able to achieve higher shutter speeds, deeper depth of field, or both. This can be of great benefit for freezing motion or getting more of a given scene in sharp focus.

There are some trade-offs for this magical ability to record light more brightly, however. These include image noise (which can be ugly or reduce detail), reduced color fidelity, and reduced dynamic range. Typically the higher your ISO setting, the more prominent these effects become. 

So, knowing these things, just how high should you go with your ISO setting?

In this image, my lowest possible ISO setting of 100 in combination with an ND filter allows for a long exposure to blur the water.

How High Should You Go?

The Short Answer

The short answer is “as high as you’re comfortable with” or “as high as you need to for the photograph you’re trying to make.” Essentially, it boils down to “it depends,” which isn’t really all that useful. Let’s dig a little deeper.

The Long Answer

Consider Your Final Output

Remembering that noise, reduced color fidelity, and reduced dynamic range are the results of increasing your ISO, will these changes affect your final output? 

Perhaps you’re working for a client who needs an exact color to be represented in the resulting image. In that case, you will probably want to keep your ISO at the sensor’s base ISO to ensure the highest fidelity in your images. 

Another situation where you might want to keep the ISO as low as possible is a scene with a wide dynamic range. An example of this is a landscape scene with deep shadows and also bright highlights. By keeping your ISO at its base setting, you are able to record as much information in the shadows and highlights as your sensor will allow. 

Consider the Scene

One of the benefits of raising your ISO is being able to use faster shutter speeds. So, for example, if you need to freeze action, raising your ISO can be beneficial. It can also help you to avoid camera shake induced by slower shutter speeds when handholding. This is one of the times when I will raise my ISO as high as I need.

It might also be that you need more depth of field. In this case, raising your ISO one or two stops to allow the stopping down of your aperture might be the best solution for your exposure. For example, you may need 1/60 s to freeze the motion of people in your photograph, but not have enough light to do this with the desired depth of field. In this case, raising your ISO is a great solution. 

Personally, I shoot quite a few corporate events in dimly lit rooms. Most of the time, my clients do not want a flash going off because it breaks up the flow of their event. At these events, I routinely shoot at ISO 3,200 or 6,400 on my Fujifilm X-T2 or X-H1. Even though these cameras are considered to be inferior to full frame sensors at these ISO values, they perform well enough for the required output of these events. The client would much prefer to have a slightly noisy image of their VIPs than a blurry one!

In this case, ISO 800 gives me a shutter speed of 1/500. This is enough to freeze the motion of the child, which is exactly what I need.

Consider Your Subject

As we mentioned earlier, high ISOs can affect color rendition, dynamic range, and detail recording. For subjects such as people, this can have negative consequences. The natural gradation or color of skin can be negatively impacted and fine details such as eyelashes can be lost to noise. It is always important to consider your subject and how important detail and fidelity is.

Which ISO Value Should I Use?

So, all of this is great, but it still boils down to “it depends.” We are a little better informed, but we’re right back to the same problem we started with. So, how can we solve this puzzle?

The one piece of advice that applies to most situations would be to use the lowest ISO value you can get away with. This will produce the highest quality file for a given situation. So, run through the considerations above and then set your ISO as low as you can while still achieving the desired image.

Test Your Camera

Not all sensors are made equal, so it is good to test your camera in your typical shooting situations. This will give you an idea of how far you are personally willing to push your ISO on a photoshoot. For me personally, I don’t mind pushing the Fujifilm X series cameras up to even ISO 12,800 for a corporate event, but I would never do that at a family or couple session unless I really needed to. For those, I would usually stop at ISO 1,600. By that point, the noise introduced reduces the detail too much for my preferences. You might find that with a full-frame camera like the Nikon D850 or the Sony a7 III that you can go much higher and still be happy with the outcome.

In this case, an ISO setting of 6400 gives me 1/250. This is enough for me to handhold the camera and still get a sharp image. The noise is not a concern here.

How Can I Reduce The Negative Effects?

Two things primarily influence the amount of quality lost due to ISO in our day-to-day photography. Those are the ISO value and the amount of light hitting a given area of the sensor (shadow areas are the first places noise becomes visible and loss of detail is common due to a reduction in dynamic range). With the first, all we can really do is keep the ISO as low as possible. In terms of exposing, we can try to avoid deep shadows by exposing a little brighter than we normally would, or filling in shadows with reflectors, etc. 

In postproduction, we can also use our software's noise reduction features to improve the look of noisy images. Of course, this won't bring back lost color, detail, or dynamic range, but it can make an image appear smoother and more pleasing. 

In Conclusion

Now that we understand more about how changing ISO affects our images and in what situations we might want to raise or lower our ISO, we are better equipped to make decisions on what ISO value to use. The final pieces of the puzzle are your camera and your preferences. How much noise or loss of detail are you willing to accept? Do you really need all the dynamic range your camera offers for the work you do? 

As one final piece of advice, I would suggest that you not consider the effects of ISO on your image unless they adversely affect it. Do not let a little noise or lower dynamic range stop you from making your art. Take the time to understand ISO, master it, but do not let it master you. 

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Anonymous's picture

Boop

Anonymous's picture

And out comes the heuristic that "professional" is a synonym for 'excellence' and "amateur" is a synonym for 'low quality'.

But hey, you're the one getting upset at any criticism of your incredibly average images.

Anonymous's picture

Beep

Anonymous's picture

You should have stopped at the concert shot, which really isn't bad, but nothing I haven't seen. If that's the best landscape you've shot...

SMDH

Anonymous's picture

Boop

Anonymous's picture

Wait, you're now asserting that you are posting garbage photos?

Anonymous's picture

Beep

Anonymous's picture

Boop

Anonymous's picture

You don't get it, I don't care what you think about me. And honestly, I've seen as much of your work as I care to see.

Anonymous's picture

But let me phrase that differently, I deal with people suffering from mental disorders in my day-to-day professional life, I have no desire to add one to my social network.

Anonymous's picture

Beep

Anonymous's picture

Sorry, did I stutter when I said "I don't care what you think about me"?

Anonymous's picture

It's adorable the way you have edited out the comments that you are particularly embarrassed about.

I truly feel sorry for you. It must be terrible having such a fragile ego, and being so terribly insecure.

And to think all of this was because you referenced your "gear limitations" and I was rude enough to suggest an affordable way into a pro spec body.

Anonymous's picture

Boop

Anonymous's picture

You edited out your comment before I read it.

Pro tip: if you are not prepared to stand by your comments, and feel the need to delete them, then you shouldn't be making them to start with.

Anonymous's picture

Leave me alone for goodness sake! I've told you before that I can't take you seriously cos you don't have any convincing work to display. The more you comment, the more I beep and boop.

Anonymous's picture

What's the issue? One can only conclude from your behaviour, specifically the unnecessarily aggressive responses, that you want an argument. Now you are crying because you got one. You're not terribly bright, are you?

You have repeatedly tried to upset me by referencing my work, and repeatedly I have told you that I don't care what you think about me; that is the lens of your worldview, and your comments say far more about you than they do about me.

But then, if you had any insight at all, you would realise that art is subjective.

Anonymous's picture

It's like you enjoy talking to yourself. Well, here come the beeps and boops!

Anonymous's picture

You can only imagine how much I am threatened by your absolute mediocrity, and by your fragile ego and insecurity. Oh no, whatever will I do.

And again, I'll remind you that all this is because I politely suggested an affordable entry to a professional body.

You are just sad.

Anonymous's picture

Beep

Anonymous's picture

Yes, congratulations, you're a moron.

Anonymous's picture

Boop

Alex Cooke's picture

Ok, this thread is closed. Steer clear of one another.

Anonymous's picture

I never meant any harm from the beginning, but I'm not the type to keep grudges so William, I'm sorry, and I forgive you.

Krzysztof Kurzaj's picture

Nima, I'm trying to put it all together. As a professional photographer you are presenting photos from a portrait session which are shot at an unusually high ISO. You claim those are just test shots because you were testing your camera's ISO during a photo session for which you were paid considerable sum. While you present those photos as a statement to camera's great high ISO performance you further claim that you rarely shot portraits for clients who want them at ISO above 400. This statement itself is quite puzzling on its own since I've never heard of anybody requesting portraits at certain ISO setting. Also never heard of photographers testing their camera's ISO capabilities during a high paid session. Maybe testing light setup but not ISO. So in the end I'm not sure what to make out of this.

I checked your Instagram gallery. Personally I don't believe there is anything wrong with it. There are some exceptionally good photos as well as some OK ones. Altogether a nice mix of different subjects and themes. As a gallery of an amateur/enthusiast photographer it's a really solid collection of photos. But as a gallery of a professional photographer it is just not convincing. There I said it. And there is no hate here. I'm just telling you what is my impression. If you insist on being a professional photographer ans make a living (or at least half of your income) via photo assignments then I will be admittedly surprised but I honestly wish you all the best at the same time.

If you go over your various comments on this photo forum you may realize how often you refer to yourself as "professional" and how often you mention your D5300/D5500/D5600 camera and how capable it is. Someone already suggested you being insecure about your skills and gear and in all honesty you are giving every reason to believe this is the case. And I'm not sure why. I don't understand why those things seem to be so important to you. There are plenty photographers out there who produce magnificent photos. Most of them are actually enthusiasts and few are professionals. It is often hard to tell them apart because quality of their work may be very comparable at times but the truth is those who make living by taking photos rarely call themselves "professional". There is simply no reason for that as their work speaks for them. They usually also don't brag about their cameras as they use whatever they feel comfortable with and have no need to justify it.

There is no question for me that you are passionate about photography. I can tell just by looking at your gallery. You try new things, you experiment, you learn, you challenge yourself shooting different subjects. All this is very good news. Just keep doing that. There is no need to tell everyone you are professional and make a lot of money as a photographer even if that is actually the case. You also don't have to justify the fact you use entry level DSLR whenever it is for financial reasons or actual preferences. Whatever works for you. I've shot some great photos, which I'm still proud of, on my 6 megapixel Nikon D40. Nothing wrong with that. Lately I've been using mostly a point and shoot camera. Also nothing wrong with that.

Just do photography man. Express yourself and be yourself. Don't try to impress anyone by telling who you are or what camera you use. Do better photography and show people your work and you will see them really impressed.

Finally, my sincere advise, when you get into a heated exchange on the forum and it goes too far just call it a day but don't edit all your posts to "beep" and "boop" because nobody will take you seriously from that point on. Just imagine one of your clients running into those posts. It's not worth it.

Anonymous's picture

I appreciate all you've just said, but please, note that I'm coming from a different background and I've gone through things in the past that you may or may not understand. If I choose to do something, I'm not doing it because I'm foolish, insecure, or desperate, but it's because I have experienced similar things in the past and this is the best way to handle things.

Yes, I am a professional photographer with many years of experience. My Instagram account is just a gallery I use to display all my works, not a portfolio for my clients. I don't mean to brag or anything, but when someone starts attacking me because I refused his suggestion to purchase a Nikon D700, then I have to respond accordingly.

I don't try to impress people with my achievements unless they're directly attacking me. If I did, you would be able to tell from the way I caption my photos on my Instagram page.

About the beeps and boops, that's the best way to handle haters, apart from not engaging them in the first place. None of my clients will run into this, and even if they do, they most likely would not care.

Krzysztof Kurzaj's picture

And so he is gone.

Francesco Mallamo's picture

Raising iso will not increase sensor sensitivity to light, it just amplifies the signal generated by the sensor right in the camera. The statement in the article is false. It is similar to increase exposure in post. In fact some cameras are isoless at certain ranges.

Mr Hogwallop's picture

I like the hands

Ralph Law's picture

You're splitting hairs at this point.

Why shouldn't "signal gain on sensor input" not be considered "sensitivity" for the purposes of an introductory article?

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