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Moving Toward Manual Settings: Understanding ISO (a beginner’s guide)

This is the third installment in a series by Hawaii photographer Natalie Norton on becoming confident with manual camera settings.

If you are new to photography, or don’t have a clean grasp of manual settings, I recommend that you go back and read the first two installments of this series: Understanding Aperture and Understanding Shutter Speed and then come on over to learn about ISO.

Understanding-ISOThis picture of my son Cardon was a tricky one to capture. We were visiting a skate ramp at a friend’s house and it was nearly dark. I could slow my shutter speed down to a certain point, but not too far, because let’s just face it, he’s a wiggly little 3 year old! I’d end up with a blurry image FOR SURE! I could open my aperture as wide as possible (1.2 on a 50mm lens), but I didn’t want to have an incredibly shallow depth of field. I wanted at least his entire face and shoulders to be in focus. I could use my flash, but low and behold I hadn’t brought it along and the camera I had on hand (Canon 5d) doesn’t have a built in flash unit . . . SO, what’s a girl to do??! PUMP UP HER ISO, that’s what! I bumped my ISO all the way up to a mighty 1600 and got the shot. Sure it’s a little noisy (don’t freak out if you’re not familiar with digital noise, we’ll discuss it below), but nonetheless, my ISO allowed me to get the shot of my sweet little 3 year old rockin’ it right at the skate park.

Now, I’m just going to apologize in advance for all the technical mumbo jumbo. . . I’ll try not to make it too dry, BUT you’re about to be one step closer to mastering manual camera settings. Dance a celebratory jig, grab a glass of water and park your little bottom. Let’s GO!

1. What is ISO?

Your ISO settings allow you to take pictures in low light situations.

It is basically a measure of your digital sensor’s sensitivity to light. The higher the number, the more sensitive to light your sensor becomes.

2. What is a Sensor?

Your digital sensor is where your image is exposed (aka RECORDED).

3. What is Exposure?

This should be a review from the other posts in this series. Exposure is light recorded on your digital camera sensor.

4. How Does ISO Affect the Final Image?

Well, if ISO determines how sensitive your sensor is to light, and your sensor records the light (a fancy way to say records the finished image) then that sensitivity of the sensor is basically going to determine (along with your aperture which determines how MUCH light hits the sensor and shutter speed: which determines the DURATION OF TIME the light is exposed to the sensor) how bright your image will be (how much light will be absorbed by the sensor).

Ijustwontherunonsentenceoftheyearaward! Yay me!


5. What is Digital Noise?

Film is composed of lots of little circles that make up the GRAIN of the film. Digital photography is similar, except for that our little circles aren’t circles at all, they’re squares. . . a gazillion little squares that come together to create an image. Sometimes those little squares in the image become slightly visible and this is referred to as NOISE. Check it out in the image of my son above.

6. What Does Digital Noise Have to do With ISO?

Well, digital noise increases with ISO. The lower the ISO the less noise you will see (and most likely you won’t see any at all). As your ISO increases, the noise level does as well. This noise level most likely will not become significant until your ISO reaches numbers of 800 or higher (depending on your camera). Rumor has it that the new Nikon D3 has magic ISO capacities that allow for ISO’s of 1600 and even higher with NO NOTICEABLE noise whatsoever. I’ve yet to get my hands on one of those babies, but when I do I plan to give you DPSers a full report.

HERE ARE SOME BASIC GUIDELINES FOR SETTING ISO: please don’t be intimidated by my mad drawing skills. What you see below is the result of YEARS of dedicated study and commitment!

On a sunny day – set you ISO low, try 200 ISO.
On a cloudy day – bump up your ISO a little, 400 might be a good starting point.
If it’s dimly lit, indoors, evening and you are not using a flash, dial up a higher ISO – somewhere in the vicinity of 800 could work.

Remember that generally speaking the higher your ISO, the lower the quality of your image. That said, it’s important to keep in mind that sometimes grain can add a fun artistic edge to a photo. On more than one occasion I’ve been known to add grain later in Photoshop to achieve a certain look.

Here’s your ISO assignment:

I want you to test your camera’s image quality at different ISO settings. Set your camera to AV (Aperture Priority). Set your aperture to no lower than 4. . . preferably around 5.6 the purpose of this assignment is not to mess with exposure, composition or depth of field. The goal is to test your camera’s ISO capacities and how it holds up under the pressure of high ISO’s. Step outside into the open shade. Shoot an image at 100 ISO and move up incrementally through your camera’s available ISO’s all the way until you reach your camera’s maximum ISO. . . don’t worry, your camera should make up for the extra sensitivity of the sensor by shortening the shutter speed. Upload the images and check the quality. If you really want to get the most out of this assignment, I recommend that you print each image to at least 8×10 or even 16×20. You’ll be glad you did if you really want to know your camera’s susceptibility to digital noise. Study the images and determine what you feel is a good ISO range that still maintains image quality for your particular camera.

Come back soon for the follow up to these posts where we’re going to put this all together and get you shooting comfortably in manual settings! You’re so close to achieving the creative freedom and confidence as a photographer that manual settings allows. YAY!

Happy Shooting!

Natalie Norton is a wedding and portrait photographer. She resides on the North Shore of Oahu, Hawaii. Check her out at www.natalienortonphoto.com.

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Natalie Norton
Natalie Norton

is a writer and a lifestyle wedding and portrait photographer who shoots across the globe. She is based off of the North Shore of Oahu and out of Gilbert, Arizona. Enjoy more of her photography and writing at www.natalienortonblog.com. You can also connect with Natalie via Twitter or on Facebook.

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