Photography basics: ISO

Have you ever been in a situation where you’ve taken one great shot after another only to get home and realize that the photos are all pixellated and grainy-looking when you pull them up on your computer? If so, there’s a pretty good chance that your ISO was high. I don’t know about you, but I’ve had several cameras and phones that would consistently give me grainy photos when I was shooting indoors on Auto. In today’s photography basics post, we’re going to take a look at ISO and what you can do to about it.

ISO is an acronym that stands for International Organization for Standardization. It’s a standardized scale for measuring your camera’s sensitivity to light; in the olden days, this actually had to do with the kind of film you were using. You can read more about that here since I’m focusing on digital photography. In the digital world, ISO determines how sensitive your camera’s sensor is to light. A higher ISO makes it more sensitive, so you can take photos with a high shutter speed or with a small aperture in low light. However, ISO also introduces noise to your images, which can be undesirable.

I zoomed in on this one so the noise would be more apparent. Click to see the full version.

The noise comes from the way your camera’s sensor works. A high ISO setting causes it to group pixels together, which is what creates those grainy off-color dots you see in a noisy photo. Cameras with larger sensors tend to have more pixels and smoother images in low light. Full frame cameras, which have sensors the same size as a 35mm film frame, are really good for shooting smooth images at higher ISO settings. Of course, a full frame camera is going to set you back more than a few pennies…It may not be worth the investment if you don’t have money burning a hole in your pocket and you’re not inclined to go pro. Newer cameras (say those made within the last 3 years or so) also get better low-light photos than older cameras; they’re designed to reduce the amount of noise and give the grain aesthetic appeal.

In my experience, I got a lot of noisy photos when I was only shooting in auto. Since I’ve switched to manual and taken control of my exposure, I rarely have issues with noise anymore because I try to keep my ISO setting as low as possible. Sometimes it’s unavoidable depending on what you’re trying to photograph, though.

Typical situations where you might want a higher ISO setting are indoor sporting events, concerts (make sure photography is permitted before you go), caves, nighttime or overcast outdoor shoots, or anywhere you need to take a quick picture but just don’t have enough light. Extremely long exposures can also create noise by causing your camera’s sensor to overheat–which is another reason you need to make time to really learn the strengths and weaknesses of your gear. A flash will help but it can also make your images look harsh or washed out, and some places don’t allow flash photography, so it’s not always the best way to go.

Here are a few examples. I took these pictures at the Lost Sea Adventure, a cave in Sweetwater, TN.

This formation was well lit already, but shooting with a low ISO was still too dark. Flash helped to brighten things up a bit more and it doesn’t look too washed out.

 

Anthodites on the cave ceiling. The noise example above is a zoom-in on this shot.
The sea itself is stocked with rainbow trout. Again, you can see the graininess in the water that’s due to the high ISO setting.

Later, I’d like to come back to this subject and talk in detail about things that can be done to reduce the amount of noise that’s present in photos taken with a high ISO setting. For now, I’m just going to give you a few bullet points.

  • Newer cameras have some built in noise reduction, and if your camera is less than about 3 years old, this post may be irrelevant to you. But if you’re a dinosaur like me, there are things you can do without shelling out the big bucks to replace your camera. I mean, unless you just want to buy another camera. (Don’t we all? I like my T3, but I’d looooove to upgrade to a full frame).
  • Keep your shutter speed as low as possible and your aperture as wide as possible.
  • Use a tripod and shutter remote.
  • Consider shooting in black and white instead of color.
  • Shoot in RAW whenever you can. JPEG files are already compressed and inherently contain noise called JPEG artifacts. I have my camera set up to record images as both a RAW (CR2) file and a JPEG. The downside to shooting in RAW is that you have to convert the files before you can upload them anywhere, and a lot of low end editing software and web apps don’t support the RAW format.
  • Edit. I can’t help you much with this one at this time, but you can find tutorials online if you look. The laptop I have right now doesn’t support Photoshop or Lightroom very well. When I upgrade to a better system, I’ll go over this in more detail. I know there are people who criticize photographers for editing photos, but I think some editing is just a part of the process. Authors don’t get criticized for editing their books. How is cleaning up some noise any different than ironing out spelling errors or bad dialogue?

I think that’s all I’ve got for today. Next week, I’m planning to spend a little time going over the math behind the elements of exposure and the relationships they have with each other and with your camera’s sensor. It’s going to be a little more advanced, but I’m hoping it won’t be confusing if you read my other posts first (links in case you missed them: exposure, shutter speed, aperture). In the meantime, please make sure you share this with your friends! Do you have any questions for me? Is there a topic you’d like to see me cover as part of my basics series? Please let me know by leaving a comment below. Thank you!

Photography Basics: Exposure at a Glance

Welcome to my basics series! Although a lot of my posts involve DSLR shooting, since that’s what I primarily use, I wanted to create some articles that would be universal to photography with almost any digital camera. For those of you who don’t know, DSLR stands for Digital Single-Lens Reflex, and it refers to the way the camera uses a single lens and a mirror to process light into images. At this time, I’m more interested in the art of taking photos than in the more technical details of how a camera works; I’m planning on writing some posts in the future about different types of gear when I start getting ready to upgrade my equipment, but today is not that day. Today we’re talking about exposure, which is the foundation of photography no matter what kind of camera you’re using.

But I won’t leave you tech fans high and dry. If you want to know more about the differences between types of cameras on the market, here is a Wikipedia article that talks about DSLRs, traditional digital cameras, and the newer mirrorless system cameras. Enjoy!

Exposure is basically how bright or dark your image appears. It’s something I’ve touched on before here and here, but so far have not discussed in detail. It’s one of those things that seems simple in theory but can be tricky to master.

I’m going out on a limb here and guessing that most beginner photographers shoot in Auto, or whatever their camera’s approximation of Auto is. It’s easy and safe, and most cameras will probably produce decent pictures in Auto. There’s nothing wrong with that.

But what if you want to do better than decent? Well, then it’s time to get out of the safe zone that Auto mode provides and start taking control of your photography. This is a process, by the way–don’t be discouraged if your pictures are bad at first. Set aside time to practice and you’ll eventually see your hard work pay off.

This was taken on auto at sunset. It’s not a bad photo overall, but I prefer the manual version below.
This one was taken in manual, just a few seconds after the auto picture. It is a bit darker, but I feel like the sunset looks much deeper. Honestly, I probably should have gotten in place a few minutes earlier.

The first step in the process is to dig out your camera manual and figure out how to change the settings. You’re looking for three things–shutter speed, aperture (or f-stops), and ISO. If you don’t have the manual, look for your camera model in a search engine and see if one is available to view online or download. If you’re shooting with your smartphone, consider an app that will give you that level of control over your phone’s camera. Open Camera (Android) or Halide (iOS) came up after a quick Google search for me; I don’t use either of them, though, so I can’t tell you how well they perform. You’ll have to try them out on your own and then come back and tell me about them. (I’m 100% guilty of leaving my phone in Auto all the time; I don’t take pictures with it all that often.)

Step two is learning how these three elements interact with one another to create an image. This one’s going to take some practice. For now, we’ll just go over what the elements are.

Shutter speed–In a digital camera, shutter speed refers to the amount of time the camera’s sensor is exposed to light. In a nutshell, high shutter speeds are good for bright places, while slower ones will allow more light to reach your sensor when it’s dark. But wait, there’s more! Your shutter speed will also determine how much motion is in an image. A high speed will allow you to capture subjects in motion while lower speeds introduce blur. Shutter speed is usually measured in seconds or fractions of a second. We’ll talk more about this next week.

This was shot at a fairly high (I want to say 1/250 but of course I didn’t write it down) shutter speed. As you can see, the water in the fountain is “frozen” midair.
Same fountain, same time, the big change was a much slower shutter speed. I also had to adjust aperture to keep from overexposing the shot. You can see the motion of the water here, and the background is brighter as well.

Aperture–We’ve talked about aperture before, and we will again. You can’t have a complete understanding of exposure without learning about all three elements, and I feel like this one allows you a great degree of creative control over your photos. Aperture is the opening in the lens of your camera (and different lenses will allow you to achieve different apertures, which is another bonus of a DSLR or a camera that allows you to switch out lenses); it’s measured in F-stops. Small numbers are wider openings, which allow more light to pass through the lens. Large numbers are smaller openings and let in less light. But that’s not all! Your aperture also determines your depth-of-field, or which parts of the photo are in focus. Large numbers are good for landscape photos or pictures where you want everything to be the same level of focus. Small numbers are good for softness or artistic blur.

This field of sunflowers was shot at a high f-stop (I want to say 16 or 20), so all of the flowers have about the same amount of focus.
This sunflower was shot at an aperture of F 1.8, the widest I can produce at the moment. The image in the foreground is fairly sharp and the soft background makes it stand out even more.

ISO–The ISO determines how sensitive your camera is to light. Lower numbers are less sensitive, while high numbers are more sensitive. Like shutter speed and aperture, ISO is also a twofold element. A high ISO will allow you to take photos in darker environments, but it also introduces noise to your photos. I don’t care for noisy photos, and I had a serious problem with cameras taking very noisy pictures in low light. So taking control of this was a big deal for me. I tend to shoot with a low ISO and only change it if I can’t get the shot I want by altering my shutter speed and aperture.

Here’s an example of a photo with noise. I shot this on Auto a long time ago. See all the speckles in the background? That’s noise caused by a high ISO.

When you’re getting ready to take a photo, exposure is one of the first things you need to consider. It’s not just how bright or dark you want your image to be, but also how you want to capture motion, depth-of-field, and the amount of noise you’re willing to put up with to achieve your desired shot. It’s a balancing act. Over the next few weeks, I’m going to try to show you how to manipulate all three of these elements so that you can find the balance in your own photography.

Thanks for reading, everyone! Please come back next Friday for a more in-depth look at shutter speed. I’m working on putting some really cool stuff together for you. In the meantime, you can follow me on Facebook for more pictures, articles, and other goodies.