Exposure : Part 2

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Now that you have a basic understanding of exposure, let’s dig deeper to get more creative.

You can get a proper exposure at various apertures, shutter speed or ISO, but understanding these three elements gives you creative control over where to set each value and how your image will look.

So, if you want to get beyond using Automatic Mode on your fancy camera, and add your creativity, you’ll need to understand some numbers.

Once you get a grasp of these exposure settings, you’d be able to capture images the way you want, not what the camera thinks you want.

Here’s a photography exposure chart I wrote up. I didn’t come up with these. These are universal ISO, shutter speed, and aperture values. You can dial up and down each of these settings in 1/3 increments in your camera. In the chart below, the numbers in bold represent a full one stop.

photography exposure chart

As we look at the following images together there are two things I want you to pay attention to:

1) How you can keep the same exposure in different images by choosing different ISO, shutter speed and aperture settings

2) Depth of Field. Look how the flowers behind the basketball become more in focus as the f-stop numbers increase.

The use of depth of field can play a huge role in your creativity, whether you’re into shooting portraits, landscapes, macro etc.

For illustration purposes, I’m going to use full stop increments to make it easier to understand. So, refer back to the chart to follow along as I share about changing the setting numbers.

First image settings: ISO 200, f/2.0, 1/250.

The flowers are only about 5 feet behind the ball, but with a shallow depth of field at f/2.0, you wouldn’t have exactly known they were flowers.

For the second image, I raised the aperture by 3 full stops to f/5.6. From 2.0, I jumped to 2.8, 4.0 to 5.6. That means, the lens opening got smaller.

So, in order to get the proper exposure I got in the first image, I need to make a change by 3 full stops to the shutter speed, or ISO, or a combination of both. Since the aperture got smaller by raising the f-stop number, I need to let more light in the camera somehow by slowing down my shutter speed, or by increasing the ISO sensitivity.

Straightforward options:

1) Keep the ISO at 200, and decrease the shutter speed by 3 full stops to 1/30.

2) Keep the shutter speed at 1/250, and increase the ISO by 3 full stops to 1600.

But instead, I decreased the shutter speed by 2 full stops to 1/60, and increased the ISO sensitivity by 1 full stop to 400. Still resulting in change of 3 full stops to keep the same exposure.

Reason: I know my camera performs well at ISO 400 and even at ISO 1600. However, ISO 1600 was not necessary even though it was an overcast day, because there was still plenty of light. And shutter speed 1/30 is slow and not worth the risk of getting a blurry image by my unsteady hands. Bottom line, there was plenty of light to use different settings to capture the image, so I didn’t feel the need to push my camera to its limit.

I’m always looking keep the ISO as low as possible, and my shutter speed as fast as possible to get the best image possible. Second image settings: ISO 400, f/5.6, 1/60.

Another fine option would have been to increase the ISO by 2 stops to 800, and decrease the shutter speed by 1 stop to 1/125.

Let’s look at the last photo. From f/5.6, I raised the aperture by another 3 full stops to f/16.

Straightforward options:

1) Keep the ISO at 400, and decrease the shutter speed by 3 full stops to 1/8.

2) Keep the shutter speed at 1/60, and increase ISO by 3 full stops to 3200.

But instead I decreased the shutter speed by 1 full stop to 1/30, and raised the ISO sensitivity by 2 full stops to ISO 1600.

Reason: Quite simply, as I weighed my options, it came down to shutter speed 1/30 was better than 1/8, and ISO 1600 was better than ISO 3200. Third image settings: ISO 1600, f/16, 1/30.

Another option would have been to decrease the shutter speed by 2 full stops to 1/15, and increase the ISO 1 full stop to ISO 800. Though ISO 800 was tempting, there was too much risk at getting camera shake and ending up with a blurry image at shutter speed 1/15.

So as you take pictures, you have to ask yourself several questions, and weigh your options:

What’s the purpose of my photo?
What f-stop is my lens capable of?
Do I want to use a small aperture(high f-stop number) and include the background?
Do I want to use a wider aperture(Low f-stop number) to isolate my subject and blur the background?
How well does my camera perform at high ISO?
Do I want to risk getting a blurry image by slowing down my shutter speed too much? or do I want to use a faster shutter speed to get a crisp image with no movement?

The questions are endless, but understanding exposure, ISO, shutter speed and aperture enables you to know your options and have the creative freedom.

Is it coming together? Confusing isn’t it?

The best way is to learn is to practice.

Have fun!

Be sure to learn more about exposure from other posts on PTC:

Shutter Speed
Exposure part 1

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4 Responses to Exposure : Part 2

  1. Eugene 05/03/2012 at 9:56 am #

    Great writeup Peter. Wish I had these when I got into photography :)

    • Peter Bang 05/03/2012 at 9:59 am #

      Thanks Huge:) Miss you man. What do you shoot with?

  2. lyn 03/15/2013 at 9:44 pm #

    Thanks Peter – I feel this will help me with my exposure journey. Usually, I try and keep my ISO as low as possible.
    Will practice as you advised.

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