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Monday, February 1, 2010

DSLR Made Easy - Part 5 [ISO]

Part 5:

Now, there is another aspect that can affect all of the other parts we’ve talked about so far. That is ISO. My P&S has an ISO setting but it wasn’t until I bought my DSLR that I figured out what it meant. ISO has to do with how sensitive your camera is to light. Low ISO means your camera is at about normal sensitivity to light. Low ISO is best for bright/sunny days. High ISO means that your camera becomes more sensitive to light. You can use High ISO when there isn’t much light available.

ISO ties into the days when we used film. If you think back, you might remember that the packages for 100 film [which is actually 100 ISO film] were designated for Outdoor photos only. The 200 film was for Indoor/Outdoor. 400 film was for action shoots, and 800 film was for low light/night photography. Or something like that.

That is because of how sensitive that film was to light. ISO 100 film wasn’t very sensitive to light, so it was best for outdoors when there was a lot of light available. ISO 800 was really sensitive to light so it was necessary for taking pictures at night or in low light. If you tried to use ISO 100 at night, your photos would be pitch black. You had to use whatever fit the situations you were shooting in.

That brings us to ISO today. If you are shooting at 100 ISO, your camera isn’t very sensitive to light. This doesn’t matter if you are outside because the conditions outside are usually always bright. However, if you are inside, this ISO becomes more important. Say that you are in your living room and you are trying to take a picture of your baby. Your room is pretty dim, so when you set your aperture as low [letting in as much light as possible] as you can, you set it to f/3.5. Then, watching the exposure meter marker inside your camera, you fiddle with it until you see it hovering around 0. The shutter speed needed for it to be at 0 or perfectly exposed, is 1/15. 1/15th of a second. For most people, 1/15th of a second is pretty slow and you can easily get some blur. Not just from your own hands holding the camera, but your baby is probably going to wiggle and kick during that 1/15th of a second. It might seem like a short amount of time, but do some experimenting. It only takes one tiny, tiny bit of movement before you’ll see a whole blur in your photo instead of your cute baby’s face.

So what do you do? You can’t use the 1/15th shutter speed to get a good picture, and your aperture is as low as it can go in your lens. You can’t make it go any lower to let in any more light.

You raise your ISO. Try going to ISO 200. That makes your camera a little bit more sensitive to light. Now, when you fiddle with the shutter speed dial, you see that when it hits the 0 mark, the shutter speed needed is 1/25. You have made the necessary shutter speed go from 1/15th of a second to 1/25th of a second. Still pretty slow but that is faster than the previous, and will give you less blur.

Try going up to ISO 400 now. When you fiddle with the shutter speed, and put it on 0, you see that your shutter speed value is now 1/50th of a second. Try taking a picture now. Did you get a good one? Probably! You still have to really try to hold still during the photo, and you might have to try to get a few in a row so that if your baby wiggles, you will get at least one clear one, but 1/50th of a second is much easier to get a good photo with, than 1/15th.

ISO sounds great, right? It is a great tool to use in low light situations. But there’s a negative to it too. ISO increases the image noise. [Note – don’t be like me and think this means actual, audio noise. I was reading my manual and kept reading ‘image noise’. I was like ‘what the heck, how does the image make noise? Maybe the camera starts to make grinding noises or something…’. Wrong.] Noise means pixely, splotchy, unclear images. I know, that makes it sound horrible, but it’s not always horrible. Once you’ve seen image noise, you’ll understand what I mean, and you’ll never forget what it is. Turn your camera to A-priority mode and make sure your ISO is set to 100. Take a picture. Then turn the ISO up to 800 and take another picture. Turn it up as high as it can go [mine is 3200] and take a picture. Then go look at them in the display screen. The ISO 100 one should be the clearest. Zoom in to view the pixels up close. Look at the 800 one. Then the 1600/3200 one. Can you see the difference? The kind of splotchy quality? That is image noise.

[Here is an experiment to show you the effects of ISO. This photo is taken with the ISO set at 100.]

[ISO 200]

[ISO 400]

[ISO 800]

[ISO 1600. You'll notice the increased splotchy-ness around the Scotch Tape roll. And on the blue plastic of the crate.]

[ISO 3200. Here the noise is very noticeable. Everywhere.]

Some noise can be ok. In the case with taking photos of your baby in the living room: you’d rather have some image noise and get a picture where you can actually see your baby’s face, than use ISO 100 and get a huge blur of a face as they turn their head at the moment you press the shutter button. Sometimes, you can’t see image noise unless you zoom in.

My rule of thumb, at least on my current camera, is that I can use up to ISO 400 pretty decently. If I absolutely need to, ISO 800 can work, but the photos are pretty noisy. Anything above that is not too good.

Some cameras are better with image noise than others. Try out your camera to see what you think.

[This is a photo with the ISO at 1600. It is noticeable and the photo has some blur because it was literally so dark out, that I couldn't keep the camera still enough to have no blur, even with the ISO at 1600. The second photo, see below...]

[... has the ISO set at 3200, my max. As you can see, the photo is very, very grainy. It isn't blurry, because I was able to hold it still enough during the photo [shutter speed was fast enough to reduce blur], but it is very noisy. In this situation though, the alternative to bumping up the ISO and getting a noisy photo is not getting a photo at all. If I wouldn't have bumped the ISO up, I would have had one massive blob of colors from the lights and my own hands shaking, with black around it from the night sky. I wish I would have taken one for comparison but this was in Universal Studios in Florida and at the time, I wasn't thinking about writing up a photography tutorial... I was waiting on a boat to take us to the City Walk! Ahhh, vacation.]

So, if you are in a situation where you can’t seem to be able to get a good photo because there’s not enough light to get the settings right, try to bump up the ISO. It might save you. You could use your flash too, but there are a lot of professional photographers that HATE, and I mean HAATTEEEE using a flash, especially the pop up flash that comes on the DSLR. The light is bright and harsh and artificial looking, they say. It blows out the subject of the photo, whether that be faces or flowers, and makes very harsh shadows appear. They’d rather have image noise and a natural coloration in their image than use the flash. That is up to you and your personal taste though. Just know that ISO can be a friend of yours, if you use it wisely.


Now you know the basics of Aperture, Shutter Speed, how the two make up Exposure, and you know about ISO.

My plan is to write up another post or two, about the Rule of Thirds and about the basics behind creating a silhouette. That's something I finally learned once I put the pieces together about metering and about manual settings. Some really neat photos can be taken when silhouettes are involved.
Stay tuned! Also, if there is anything that you have been wanting to learn, to refresh upon, or that you've seen and have no clue how to do it, please let me know in the form of a comment. If I don't know how to do whatever you mention, I'll find out. After the Rule of Thirds and Silhouette posts, I don't have any other posts in mind, yet. So, let me know!
Get out there and play around with your camera! See what you can do with it!


  1. This is so helpful (as are all of your posts!)... thanks, again! :)

    How about some tips on editing?

  2. Thank you so so so much! This was the best tutorial of how the three work together!!! One thing I am confused about it when to use the flash. I know that the best photographers try not to use a flash, but when should we? I got a 50 mm. and whenever I set it on Manual, my photos are blurry, as soon as I set it at Auto, the flash comes on and the picture is clear but too bright.

  3. Yes, you are right - the pros tell us to avoid flash at all costs. Sometimes, that seems impossible though, right? When you set it to Manual, what are your aperture and shutter speed settings? Also, what are you trying to photograph? Is it blurry because you are using a slow shutter speed and are getting camera/motion blur, or is it noisy from bumping up your ISO? The flash on your camera is really hard to control. I was just reading today how to use a flash to get the most natural effects. It was talking about an external flash unit though, one that has a pivoting head that you can bounce off the ceiling/walls etc. You are really limited with the flash on your camera. One thing you can try to do is set your flash to fill-flash. This may or may not work, but in theory, it will make the flash less strong. It'll just act as a 'filler' to accompany your existing natural light.

    The trick when using the 50 mm lens is to find an ISO that allows you to get your shutter speed fast enough for whatever you are photographing, but not getting too much noise in the process. If you are photographing people that can sit still, you could try to use a tripod and that will let your slower shutter speeds work better. If you are photographing squirmy babies, then you have to do the best you can - to increase your ISO to maybe 400 or 600 if you can, and then to make your shutter speed as fast as it can be.

    Oh, and I should also mention this because I often forget: inside, when you set your aperture to 1.8 or whatever your 50 mm lens will go to, you have a very shallow depth of field. So motion/movement aside, there will be a small part of the photo that is in focus and the rest will be unfocused - that's what happens with small aperture. So, if you are trying to take a picture of a couple of kids together, using an f/1.8 might not work because not all of the kids will be in focus. You'd then have to increase your aperture value to get a deeper depth of focus, and probably use the flash.

    I hope I haven't confused you and caused you to retract your statement about this being a helpful tutorial! :) If you want a more detailed description, or if I've confused you even more, email me: lauraradniecki@hotmail.com. I can explain things more detailed there!

  4. Thanks Laura, you made things even clearer. I can't tell you how excited you have made me that I know have finally grasped it!!! Although, I am totally bummed because just yesterday after I learned all of this, my readings on my camera (inside when you are getting ready to take a pic) just went crazy. They are all mumbled and you can't even read the numbers and all the lines are lit up on the metering. UHG I am so sad I have to send my camera in to have it fixed.
    Also, thank you for posting on my blog. That beach is in Oahu right by our hotel. I can't remember the name of it at the moment, but I loved it there. We went to North shore there as well and got some beautiful shots of the water. It was so clear and looked like swimming pool water! I bet you loved living there! My husband and I are going to go to Maui for our 20th anniversary in July and I am excited to see that island as well. You should go and check out "I heart faces" they have contests every week and it is just a fun way to challenge yourself. They have guest photographer judging the photos. This week was kissing and I just didn't have time to do one! Thanks again for all of your help!


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