Principles of Photography-ISO – Controlling camera’s light sensitivity

by on November 22, 2009

iso digital photography

In our Principles of Photography Workshop Series we try our best to share what we were able to teach ourselves about photography, in simple, easy-to-understand concepts. These are just some basics to help you get started, there is much more information to learn beyond these basics. But by understanding the most basic principles of photography then building upon them through practice, practice and more practice, you can capture the type of images that you want.

Note: Teaching and understanding photography can be often be complicated and confusing. Of course, there are many ways to explain these concepts & there is no “right” way to teach this. So if you think you can explain it better, then obviously you don’t need our help. :D Now, everyone grab your camera and let’s start figuring this stuff out together! And have fun!

For those of you who have been following this series, we all have gone over most of the elements that make up Exposure. First there was Shutter Speed, then we went over Aperture. With this post we’ll go over the final main element of how your camera gets its Exposure, ISO, then we’ll try to tie them in all together.

What is ISO on your camera?

  • ISO refers to how sensitive your camera is to light. Originally this referred to the film, but with digital cameras, the ISO sensitivity is in reference to the camera’s sensor.
  • Basically, the more sensitive your camera is to light, the higher the ISO number, the more possible it is to shoot in low light situations.
  • Higher ISO number = higher sensitivity to light = better ability to shoot in low light

iso grain noise photograph A “Noisy” photograph is grainy & speckled.

How is ISO measured?

  • ISO is measured by numbers that are based on an older film standard. For example, film comes in different speeds such as 100, 200, 400, 800 and above. Recommended film speeds for daylight or bright, outdoor situations usually calls for 100-200 speed film. Darker situations, indoor shots or sports shots called for the higher speed films.
  • The same number now refers to the the sensors on digital cameras, which are measured in the same numbers.
  • The lower the number, the less sensitive, the higher the number, the more sensitive the camera’s sensor will be. The numbers can range anywhere from 50 to 6400 and beyond, depending on the camera.
  • So, if you’re shooting in lower light situations and your pictures come out too dark, you can increase your ISO number to make it more sensitive to light, making the photographs brighter.

How do you control ISO?

  • Almost all cameras will allow you to manually adjust your ISO setting, however many also offer an Auto-ISO mode, or something named similarly. Usually in this mode, you are able to tell the camera the parameters you want it to stay in (highest ISO, lowest shutter speed.) Check your manual or search online for your individual camera on how to do this. Every camera varies.

Example of ISO light sensitivity: One way to control your exposure is by controlling the ISO

iso digital photography

In the above examples, ISO 100 is dark, but as the ISO is increased to 320 and 800, the exposure is increased, thus, more light into the image.

What is ISO in digital photography ?

As the ISO continues to increase, more light enters the photo. But as the ISO increases you can start to see Grain & Noise (read below)

How will controlling the ISO help with your photography?

  • Increasing the ISO (which increases the camera’s sensitivity to light) allows you to capture images in lower light. However it does come at a cost.
  • Potential Problems– Noise & GrainThe higher the ISO, the more the camera will pic up other atmospheric stuff resulting in “noise” or a graininess in the image. Usually this isn’t appealing although sometimes you can use it stylistically for a very cool image. Ever camera sensor is different, but usually the better the camera, the higher you are able to raise the ISO without experiencing noticeable “noise.” Some cameras will start showing noticeable noise as low as ISO 400, while others may look great up to ISO 800, 1000, or even 1600.
  • Increasing the ISO will expand your camera and lens’ limits in particular environments:
    1. Increasing the ISO, you can use a faster shutter speed, lessening the chances for “camera shake” or allowing you to freeze motion a little better. See Shutter Speed post to help understand this.
    2. Increasing the ISO, you can use a more shallow aperture setting (higher number), allowing you to get a deeper depth of field. See Aperture post to help understand this.

Creative choices with Grain & Noise- Sometimes high grain pictures can be artistic & are used frequently to convey a vintage, gritty, raw and moody quality to your photographs. You can decide!

high grain noise photographabove: the high grain “noisy” images creates a textured, artistic quality to black & white photographs. Grainy images such as these convey an old style photograph reminiscent of film

Final thoughts on ISO

  • ISO is the third and final element to how your camera captures light to get its exposure. Remember, Shutter Speed (how long the camera captures light) + Aperture (how much light – how big the “hole” opening is in the lens)+ ISO (how sensitive the camera is to light)= Exposure (the total amount of light used to create your image).
  • Controlling ISO is usually done creatively more for the purpose of helping either the Shutter Speed or Aperture, or both. By itself ISO doesn’t have much creative qualities other than to introduce “noise” at higher ISO settings (which as mentioned before, can be kinda cool at times.)
  • Play with your camera to see at what point you start noticing noise in your images. There are ways in many editing software programs to help reduce or clean up noise in photos, so even if you have to shoot at a higher ISO than you’d like, sometimes you can still get fairly clean image after editing. A “noisy” image is better than no image or a super underexposed (dark) image.

When you are ready to shoot Manual ~ Putting it all together ~ Exposure= Shutter Speed + Aperture + ISO

After playing with each of the individual elements of exposure & understanding what they all do by themselves, you can develop the freedom of completely controlling your camera by putting it all together and shoot on the Manual Mode.

Here are a few things reiterating on the principles of Exposure and to hopefully help ease the confusion and frustration of shooting on manual:

  • Shutter Speed and Aperture work inverse of each other while ISO is a third party that only increases the sensitivity of the camera. What that means is:
  • If you aren’t touching the ISO, shutter speed and aperture work like two sides of a scale to get a proper exposure. If you increase one, you have to decrease the other in order to get the same exposure.
  • If you are shooting and the shutter speed is more important to you, lets say you’d like to increase the shutter speed (shutter opens and closes faster) in order to freeze the action better; you’ll have to decrease the aperture number (the hole gets bigger letting in more light.) Say f/8 and 1/60 get a good exposure. To get approx. the same exposure but freeze the action better, shoot at f/2.8 and 1/500 (if your lens will get that big of an aperture ~ many won’t).
  • If you are shooting and the depth of field is more important to you, let’s say you want a deeper depth of field, you can make the aperture number got bigger (the hole is now smaller-remember the drapes analogy) then change the shutter speed to a smaller (slower) number and now it will stay open longer and you’ll to get the same exposure. If you shot your image at f/4 aperture and 1/60 shutter speed, you could shoot at about f/13 aperture and 1/5 shutter speed and get about the same exposure.

Now in this situation where we would be shooting using a slow shutter speed, it would be very hard to shoot only holding the camera by hand because the shutter is so slow you will certainly have camera shake. There are three main options to help this.

  1. Increase the light available by using a flash, upping the lights or shooting in a brighter spot. Now you”l be able to shoot using a faster shutter speed to get a good exposure.
  2. Use a tripod or prop the camera on something to take the shot. However, if your subject is moving, you will still get motion blur ~ this can be stylistically cool, though.
  3. Increase the ISO to make the camera more sensitive to light. However increase too much and you’ll start getting a “noisy” image.
  • Obviously, these all work if you want to go the other way, too. If you want a slower shutter to capture more flowing motion, decrease the shutter speed (shutter opens and closes slower letting in more light) and increase the aperture number (making the hole smaller letting in less light). If you want a more shallow depth of field, decrease the aperture number (increases the hole size letting more light in) and increase the shutter speed (shutter opens and closes faster letting less light in).

Is it all starting to make sense? Or is you head spinning like you just pounded 4 Long Island Iced Teas, was spun around and then someone asked you to pin the tail on the donkey? If it doesn’t make sense yet, don’t worry. It takes time, practice, and repetitive experience to fully wrap your brain around this stuff. Remember to practice each element by itself by shooting Shutter Priority, Aperture Priority and by shooting manual and only adjusting the ISO to see how they all behave. Understand each element comfortably, then move on to try and put them all together. This is at least what we’ve done for ourselves and it has helped us learn and understand photography by self-teaching. Hopefully it will help you on your way to becoming fluid and comfortable with you camera.

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Photography Series: Understanding these concepts one step at a time will help you capture the images that you want.

1. Exposure
2. Shutter-Speed – “Controlling Motion”
3. Aperture – “Controlling Depth of Field”
4. ISO
5. White Balance
6. Flash Your Food Photography #1- Using Built-in Camera Flash for DSLR and Point & Shoot. Includes some tips to making your own accessories.
7. Flash Your Food Photography #2- Using Speedlight Flashes ON the camera
8. Flash Your Food Photography #3 – Using Speedlight Flashes OFF the camera with remotes, sync cords, triggers and commander mode. (Cool cocktail shots will be highlighted here! )
9. Flash Your Food Photography #4 – Using multiple Speedlight Flashes or Strobes OFF the camera. Short discussion of Dedicated vs. Non-Dedicated flash mounts.
10. Natural light Food Photography
11. Photography inside restaurants, kitchens and capturing Chefs in action.
12. Editing

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{ 38 comments… read them below or add one }

1 Divina November 22, 2009 at 3:46 am

My head is spinning after reading it. :D But at least I do understand a few parts of it. Well, I have to read it again, right? For me, this is easier to understand than white balance. Someone explain it to me and I still have no idea how to create the correct white balance. Thanks for another wonderful tutorial.

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2 Kalyn November 22, 2009 at 5:38 am

Great series! I am amazed that I understand most of this (so far) although I can’t always choose the settings to get just what I want when I’m shooting (not yet!) Really looking forward to the rest of the posts!

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3 Karina November 22, 2009 at 8:35 am

Fabulous information and illustration. It really is time for me to overcome my fear of going manual (not to mention, actually reading my camera manual, which makes my head hurt). Thanks for this beautiful and educational series!

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4 Lauren November 22, 2009 at 8:42 am

Loving this series! Its a lot to learn, but it certainly helps =D.

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5 Mary November 22, 2009 at 9:52 am

Very helpful post. Thanks for writing it up and sharing it.

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6 A&N November 22, 2009 at 10:05 am

You are a god send, I must say. I’ve been trying so hard to improve on my pics with a simple P&S and I thought I’ve reached a dead end!

This series is helping me a lot, as I’m sure it is, others too! Thanks so much for taking the time and effort.

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7 Charles November 22, 2009 at 11:00 am

Thank you so much for this – your explanation is so much easier to comprehend than the tech writing in manuals. Also, what is the cocktail in your gorgeous photo?

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8 Cheryl November 22, 2009 at 1:38 pm

Complete awesomeness, and not as bad as 4 Long Island iced teas, after which I would probably be dead. Can’t wait for you to get to the Speedlite tutorial. I just bought one and am afraid to touch it.

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9 Maninas November 22, 2009 at 2:21 pm

Very very helpful – well written and clearly explained. THANK YOU very much for this!

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10 Christine@Christine's Recipes November 22, 2009 at 2:39 pm

Now I can understand the meanings of the “numbers” of exposure, shutter speed, aperture at least. My head is spinning while reading how to apply to what situation. :) I need more practice as you said. Thanks for your excellent explanation of those fundamental, yet “complicated” concepts so clearly to a layman like me.

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11 Sara November 22, 2009 at 2:56 pm

i think it’s great you guys are doing this series. I am just setting forth to understand all this stuff, and yes, my head is spinning. I enjoy how you break it down, thank you!

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12 Alanna November 22, 2009 at 3:51 pm

Another building-block of the series.

Maybe along the way, you could talk more about the graininess issue. I think — right? — that graininess will be less obvious if you use an entire shot but that it will become increasingly obvious the more you crop.

And how would you suggest figuring out how high a camera can go? I think mine stops at 400 for food shots but must admit that I once took some amazing pictures after sunset in near darkness at 1600, I expected NOTHING but the camera found light somewhere and they’re quite beautiful and eerie, fog lifting off a pasture. For once, the camera saw more than the eye could.

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13 Rasa Malaysia November 22, 2009 at 4:48 pm

Another great article. Thanks for writing this. Now I know how to create artsy grainy B&W pictures, yay…no more Photoshop effect. :)

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14 Stephanie - Wasabimon November 23, 2009 at 12:23 am

You know, I was surprised to find how many of the food photographers I like shoot on auto. I shoot all manual – at least when I screw up, I know it’s all me and not the camera. ;)

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15 SallyBR November 23, 2009 at 12:29 pm

As a beginner blogger who is not at all good at photography, I enjoy reading your posts, hoping to get some pointers and improve a little… :-)

I have a small hijack on the subject, though. The other day I saw my own blog in a different computer, and was shocked by how intensely red most photos were. I browsed a few other blogs, and some seemed to look better in that computer, others (most) worse. So I guess once you “optimize” a photo, it is not that easy to ensure that it will look great in every single kind of computer… how does a GOOD photographer work around this issue? Do you go for a softness of color, or less harsh contrast as a rule?

Or do you just forget about it, and concentrate on how things work on your own browser?

Sorry if this is too much of a departure, and feel free to direct me to another post if the subject has been brought up before.

Thanks

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16 Jen @ My Kitchen Addiction November 23, 2009 at 12:29 pm

Love your explanation of ISO… I took a photography class a while back, and since purchasing a DSLR, I have been re-learning much of what I had learned previously. I had no trouble remembering all of the aperture and shutter speed details, but I definitely needed the refresher on ISO settings.

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17 Eat. Travel. Eat! November 23, 2009 at 5:11 pm

I can not tell you how helpful your series has been to me so I could easily understand the functions of a DSLR which I just got a month ago. I especially like the sample photos which make everything easy to understand. Sometimes examples are the best way to go!

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18 garrett November 24, 2009 at 9:35 am

Another amazing tutorial! Looking forward to the ones that apply to Point and Shoots. =)

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19 my boyfriend cooks for me November 25, 2009 at 2:22 pm

I’ve been struggling with lighting issues in my food photos – if you go on macro-mode, my (point-and-shoot) camera often warns that there isn’t enough light to get a good focus. My boyfriend and I have been playing with bringing additional lamps into our kitchen with dubious success, but I just did a preliminary test, and switching my ISO setting from “auto” to “hi” might be the (simpler) answer! I can’t wait to try this on food tonight!

Thanks so much!!!

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20 Deb Mele November 25, 2009 at 11:14 pm

Wow, just stumbled upon your photography posts following a tweet by Matt Bites. I have been reading and reading about shutter speeds, apertures and ISO trying to improve me camera skills, and it is coming together but your explanation is so much clearer than what I read in the books. THANKS! I will print your posts and carry them in my camera bag for a refresher when needed.

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21 barbara November 25, 2009 at 11:25 pm

I really appreciate you doing this series. Thank you.

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22 Lydia (The Perfect Pantry) November 26, 2009 at 5:30 am

Really enjoying this series. I’m with you up to now, and really looking forward to White Balance, which has always been a stumbling block for me. Thanks so much for sharing your knowledge.

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23 Angela@spinachtiger.com November 26, 2009 at 6:38 am

Again, thanks, this is really helping me. I’ve sat through photography videos,and gotten lost and bored. You need to put this in a book. I would buy.

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24 Manggy November 27, 2009 at 8:16 pm

Loving the series so far! Unfortunately my P&S is unbelievably noisy even at relatively low ISO, so I have to stick to 80-120 most of the time, unless I’m desperate…

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25 Andrea Meyers November 30, 2009 at 1:29 pm

When I first got my Canon 40D last year I thought it wouldn’t be too difficult to learn since I had been shooting in manual mode on my P&S for two years. Turns out your tutorials would have been very helpful because here I am a year later finally wrapping my head around some of this stuff. Thanks for making everything in these tutorials so clear and easy to understand.

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26 noobcook November 30, 2009 at 8:03 pm

I totally enjoyed reading your photography series – they are easy to understand and so comprehensive. Look forward to the upcoming articles :D

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27 erin December 21, 2009 at 6:48 am

this is amazing, thanks so much

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28 May March 2, 2010 at 7:13 am

amazing stuffs. Thanks
would u share Which lens would u recommend to get for nikon as well
thanks

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29 White On Rice Couple March 3, 2010 at 4:20 pm

It really depends on what would your main shooting be and what your budget is. Nearly all of the faster Nikon lenses are great, but there are different uses for each.

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30 gwen May 29, 2010 at 12:50 pm

Excellent tips! A lot of information and very well put. Thank you so much for posting this!!!

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31 gwen May 29, 2010 at 12:51 pm

I’ve been hearing a lot about DSLR. I’m almost embarresed to ask, but what exactly is it?

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32 White On Rice Couple May 29, 2010 at 7:04 pm

Technically DSLR stands for “digital single-lens reflex camera”. Not very helpful, huh? In simple terms it is used to refer to the type of digital cameras which have a body with interchangeable lenses.

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33 White on Rice Couple November 22, 2009 at 9:57 am

We’ll be going over white balance next in this series. Hopefully it will be soon, but each time we write a photography tip post it takes us forever to go over what we wrote to make sure it is explained in the best way we know how. Don’t forget to practice, practice, practice. Then some of the jumble will start to make sense.

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34 White on Rice Couple November 22, 2009 at 1:36 pm

Charles- the cocktail is a raspberry/pomegranate cocktail! We’ll have to post the recipe soon.

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35 White on Rice Couple November 23, 2009 at 10:24 am

Cheryl- Speedlights can be tricky to work with, that’s why we’re going through these photography principles first. :D

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36 White on Rice Couple November 23, 2009 at 2:05 pm

Actually this will be discussed a bit later, but for a short answer, we try to make our monitors that we edit on as color correct as is practical (we use a Spyder) and leave it at that. If other people’s monitors are incorrectly balanced, we can’t worry about that.

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37 SallyBR November 25, 2009 at 8:48 am

Thank you… that makes perfect sense.

Now of course I worry about my own monitor… :-)

I will be following all your lessons online

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38 White on Rice Couple November 27, 2009 at 9:04 pm

Manggy- Yeah, many P&S camera’s have limitations on ISO and ultimately produce grainy shots on higher ISO’s, like you mentioned. Time to get yourself a DSLR! ;)

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