The White Paper - Aperture Vs. Shutter Speed

Chapter 4 - Aperture Vs. Shutter Speed

In Chapter 3, we discussed exposure and how critical it is to quality pictures - and that you use aperture and shutter speed to control how much light comes into the camera and for how long the sensor is exposed to it.

Now things get complicated. Aperture and shutter speed not only determine exposure, but also affect the esthetics of your pictures. Quite often, these issues conflict and make it extremely difficult to get the proper exposure.

Auto Mode

In AUTO, none of this matters. The camera is selecting both aperture and shutter speed. As long as you use AUTO, you'll have to live with whatever results the camera dictates.

All Other Modes

In the H-Series cameras, all modes except AUTO give you a choice between adjusting the shutter speed, aperture or both.

Remember, you can get the same exposure with a smaller aperture and a slower shutter speed (less light exposed longer) as you do with a wider aperture and a faster shutter speed (more light exposed for shorter time). The sensor is exposed to the same amount of light.

So on what basis do you decide which combinations to use? It depends on what you want to get out of your picture. It boils down to esthetics vs. motion.

Aperture Priority

The aperture is an iris that opens up to allow more light into the camera and closes down to allow less light in. The aperture also determines, to a great extent, how the lens presents the image carried by the light.

Depth Of Field

Depth of Field (DOF) is the amount of your photo that will appear to be in focus. Imagine a string from your camera to a distant mountain. Imagine that you have an in-focus "field" of 50 feet. This field of focus can move anywhere along the string. The mountain can be in focus, but the tree near the camera will not be. Or the tree may be in focus, but the mountain will be just a gently blurred background. If the tree and the mountain are within 50' of each other, they will both be in focus!

The length of the area in focus is called the depth-offField, and it can be larger or smaller. It can move closer or farther away. Controlling DOF gives you enormous control over what your pictures look like and what they convey.

There are several determinants of DOF (see Chapter 8). Aperture is one of them.

The Effect of Aperture on Depth-Of-Field

The narrower the aperture (the higher the f-stop), the more depth of field (DOF) you have at a given focal length.

If you want everything in your field of view to be very crisp and sharp, use the highest f-stop the camera allows (f 8 on the H-Series cameras)

The wider the aperture (the lower the f-stop), the less DOF you have at a given focal length.

If you want a shot of a single flower with everything blurred beyond it, use the lowest f-stop the camera allows (f 2.8-3.7, or in the case of the H7 and H9, f/2.7-4.5)

Warning: Diffraction Effect

If you use f8, however, you have another conflict. Most camera/lens combinations suffer from diffraction effect. As the aperture gets very small, the image gets slightly softer. A trade-off: you'll have a huge depth-of-field, but the image will appear slightly less crisp and sharp. In the H1, I believe that f6.3 is the highest aperture before you hit diffraction effect, although f/7.1 is completely acceptable. In the H5-H9, you'll want to keep the aperture down to f/5.6-f/6.3 for the maximum sharpness.

Which aperture to use to maximize depth-of-field? I can't answer that. It's entirely your choice. If you shoot at f8 and maximize your focus depth, you can always counteract the diffraction effect by adding sharpening in your post-processing software. On the other hand, there is no substitute for a photo that's captured sharp to begin with.

Shutter Priority

The reason to use Shutter Priority (or to set the shutter in Manual Mode) is to control motion. If your subject moves while your shutter is open, a multiple, ghosted image will result. This effect is called motion blur. The same thing happens if you shake the camera while the shutter is open, only then it's called camera shake.

The image stabilization in the H-Series cameras is very effective. It helps with the shaking problem, but doesn't do a thing about a moving subject. Your shutter must be faster than the motion in order to "stop" the action.

Slow action can usually be stopped at about 1/125th

Moderate action (children at active play, football, butterfly's wings) can usually be stopped at about 1/200th -1/320th.

Moderately fast action (bicycle races) can usually be stopped at about 1/500th

Very fast action (Sparrow's wings beating) can require up to 1/1000th of a second or more.

It's impossible for me to tell you what shutter speed to use for a given situation.

We may both be shooting football, but my game is in the daylight, yours under the lights. Shooting in the huddle is entirely different than shooting a player running for a touchdown. The speed of motion varies. The light varies. You'll need to experiment to find out which shutter speeds stop the action for the specific conditions of the event you're shooting. Use review (left button on the H1's 4-way switch or the playback button on later cameras, while in shooting mode) to see if the picture is blurred. If it is, increase the shutter speed.

The Conflict: Aperture Vs. Shutter

Let's assume you're shooting a car race, at night, with poor lighting. You want to stop the motion of the car and have the whole field in sharp focus. To get proper exposure, you need at least 1/500th of a second at f8. This probably won't work. Your picture will start out a little soft from diffraction effect at f8 - and still, the picture will be underexposed. So raise the ISO (amplify the sensor's output). No problem, but now, if you've raised the ISO above 200 (on the H1) or 400 (on the H5-9) you've introduced noise and your picture quality will deteriorate.

The Solution

Compromise. This is why I recommend that most people do not shoot in AUTO mode. You can't compromise without control. I'm always amazed at how often I get in exposure trouble either hitting the limits of the camera or bumping up against a conflict between aperture size and shutter speed. I don't use AUTO because I can't bear the idea that there's nothing I can do to resolve these problems.

There's always something you can do to save a shot. Here's a few examples:

Shoot with flash and maintain your aperture for esthetics. More light, higher shutter speed.

Lower the aperture and clean up the result with sharpening in post-processing

Adjust both. A little less depth-of-field, a little less stop-action. Open the aperture a bit and lower the shutter speed a bit.

Raise the ISO. Balance the risk of noise with the risk of losing the shot. On the H1, ISOs up to 200 are reasonable. ISO 400 is last-ditch. On the H5-H9, ISO 400 is quite usable, ISO 800 and above are just for emergencies. You can play with NR in post-processing.

Shoot it a little dark. Sometimes I let a shot go through underexposed up to -.7 EV and fix it up in Photoshop later.

Summary:
Set the aperture if you wish to control depth-of-field
Set the shutter speed if you wish to avoid blur or shake or you wish to stop action.
As for conflicts in low light conditions? That's what makes you the artist - the choices you make.

Next: Chapter 5 - Metering Modes
Return to White Paper Introduction and Contents



	Chapter 4 - Aperture Vs. Shutter Speed

	In Chapter 3, we discussed exposure and how critical it is to quality pictures - and that you use aperture and shutter speed to control how much light comes into the camera and for how long the sensor is exposed to it. Now things get complicated. Aperture and shutter speed not only determine exposure, but also affect the esthetics of your pictures. Quite often, these issues conflict and make it extremely difficult to get the proper exposure. Auto Mode In AUTO, none of this matters. The camera is selecting both aperture and shutter speed. As long as you use AUTO, you'll have to live with whatever results the camera dictates. All Other Modes In the H-Series cameras, all modes except AUTO give you a choice between adjusting the shutter speed, aperture or both. Remember, you can get the same exposure with a smaller aperture and a slower shutter speed (less light exposed longer) as you do with a wider aperture and a faster shutter speed (more light exposed for shorter time). The sensor is exposed to the same amount of light. So on what basis do you decide which combinations to use? It depends on what you want to get out of your picture. It boils down to esthetics vs. motion. Aperture Priority The aperture is an iris that opens up to allow more light into the camera and closes down to allow less light in. The aperture also determines, to a great extent, how the lens presents the image carried by the light. Depth Of Field Depth of Field (DOF) is the amount of your photo that will appear to be in focus. Imagine a string from your camera to a distant mountain. Imagine that you have an in-focus "field" of 50 feet. This field of focus can move anywhere along the string. The mountain can be in focus, but the tree near the camera will not be. Or the tree may be in focus, but the mountain will be just a gently blurred background. If the tree and the mountain are within 50' of each other, they will both be in focus! The length of the area in focus is called the depth-offField, and it can be larger or smaller. It can move closer or farther away. Controlling DOF gives you enormous control over what your pictures look like and what they convey. There are several determinants of DOF (see Chapter 8). Aperture is one of them. The Effect of Aperture on Depth-Of-Field The narrower the aperture (the higher the f-stop), the more depth of field (DOF) you have at a given focal length. If you want everything in your field of view to be very crisp and sharp, use the highest f-stop the camera allows (f 8 on the H-Series cameras) The wider the aperture (the lower the f-stop), the less DOF you have at a given focal length. If you want a shot of a single flower with everything blurred beyond it, use the lowest f-stop the camera allows (f 2.8-3.7, or in the case of the H7 and H9, f/2.7-4.5) Warning: Diffraction Effect If you use f8, however, you have another conflict. Most camera/lens combinations suffer from diffraction effect. As the aperture gets very small, the image gets slightly softer. A trade-off: you'll have a huge depth-of-field, but the image will appear slightly less crisp and sharp. In the H1, I believe that f6.3 is the highest aperture before you hit diffraction effect, although f/7.1 is completely acceptable. In the H5-H9, you'll want to keep the aperture down to f/5.6-f/6.3 for the maximum sharpness. Which aperture to use to maximize depth-of-field? I can't answer that. It's entirely your choice. If you shoot at f8 and maximize your focus depth, you can always counteract the diffraction effect by adding sharpening in your post-processing software. On the other hand, there is no substitute for a photo that's captured sharp to begin with. Shutter Priority The reason to use Shutter Priority (or to set the shutter in Manual Mode) is to control motion. If your subject moves while your shutter is open, a multiple, ghosted image will result. This effect is called motion blur. The same thing happens if you shake the camera while the shutter is open, only then it's called camera shake. The image stabilization in the H-Series cameras is very effective. It helps with the shaking problem, but doesn't do a thing about a moving subject. Your shutter must be faster than the motion in order to "stop" the action. Slow action can usually be stopped at about 1/125th Moderate action (children at active play, football, butterfly's wings) can usually be stopped at about 1/200th -1/320th. Moderately fast action (bicycle races) can usually be stopped at about 1/500th Very fast action (Sparrow's wings beating) can require up to 1/1000th of a second or more. It's impossible for me to tell you what shutter speed to use for a given situation. We may both be shooting football, but my game is in the daylight, yours under the lights. Shooting in the huddle is entirely different than shooting a player running for a touchdown. The speed of motion varies. The light varies. You'll need to experiment to find out which shutter speeds stop the action for the specific conditions of the event you're shooting. Use review (left button on the H1's 4-way switch or the playback button on later cameras, while in shooting mode) to see if the picture is blurred. If it is, increase the shutter speed. The Conflict: Aperture Vs. Shutter Let's assume you're shooting a car race, at night, with poor lighting. You want to stop the motion of the car and have the whole field in sharp focus. To get proper exposure, you need at least 1/500th of a second at f8. This probably won't work. Your picture will start out a little soft from diffraction effect at f8 - and still, the picture will be underexposed. So raise the ISO (amplify the sensor's output). No problem, but now, if you've raised the ISO above 200 (on the H1) or 400 (on the H5-9) you've introduced noise and your picture quality will deteriorate. The Solution Compromise. This is why I recommend that most people do not shoot in AUTO mode. You can't compromise without control. I'm always amazed at how often I get in exposure trouble either hitting the limits of the camera or bumping up against a conflict between aperture size and shutter speed. I don't use AUTO because I can't bear the idea that there's nothing I can do to resolve these problems. There's always something you can do to save a shot. Here's a few examples: Shoot with flash and maintain your aperture for esthetics. More light, higher shutter speed. Lower the aperture and clean up the result with sharpening in post-processing Adjust both. A little less depth-of-field, a little less stop-action. Open the aperture a bit and lower the shutter speed a bit. Raise the ISO. Balance the risk of noise with the risk of losing the shot. On the H1, ISOs up to 200 are reasonable. ISO 400 is last-ditch. On the H5-H9, ISO 400 is quite usable, ISO 800 and above are just for emergencies. You can play with NR in post-processing. Shoot it a little dark. Sometimes I let a shot go through underexposed up to -.7 EV and fix it up in Photoshop later. Summary: Set the aperture if you wish to control depth-of-field Set the shutter speed if you wish to avoid blur or shake or you wish to stop action. As for conflicts in low light conditions? That's what makes you the artist - the choices you make. Next: Chapter 5 - Metering Modes Return to White Paper Introduction and Contents