Choosing a shutter speed (continued)

What are the factors affecting shutter-speed choice?

• Aperture setting
• Subject movement
• Camera movement
• Lens size
• Available light
• Tripod
• Artistic effect
• Film speed

 

Notice how, in this case, a wide aperture - f2.8 - kept the subject sharp while throwing the background out of focus click on the image to enlarge

Aperture setting:

We have alread discussed the relationship between shutter speed and aperture and how one affects the other.

But consider if you want a fast shutter speed like, for example a dull day with diffused light. You may want (for various reasons) to choose 1/2000th of a second, but in the low-light conditions, even the widest aperture won't allow enough light to hit the camera. So, aperture in these circumstances won't allow the shutter speed you want.

 

Subject movement:

If the subject is moving you will want to freeze the action. In other words you don't want a picture where the subject or parts of it are blurred (or do you? That's where artistic effect can come in).

To freeze the action you must use a fast shutter speed.

But remember the relationship between shutter speed and aperture? ... if you increase your shutter speed (letting in less light) you must compensate by opening the aperture by a commensurate amount (to let in more light).

A rough guide:

 

Here's a tricky situation where compromise was needed. Travelling in the back of the lead aircraft, I decided I would have to use a high shutter speed (1/500th) to combat vibration. This, however, almost "stopped" the propellers on the subject aircraft (below). A more natural effect is achieved by using a slower shutter speed (1/125th) above. The vibrations of the aircraft I was travelling in were overcome by relaxing my arms to dampen the movement. I also took about 100 shots to get about 20 good ones. click on the images to enlarge

Camera movement:

The camera may be moving for a number of reasons;

Again, shutter speed needs to be increased to freeze the action - or, you could do something to eliminate the movement.

 

Lens size:

Shutter speed needs to be increased in proportion to the focal length of the lens.

Unless you use a tripod, some body movement is unavoidable.

Long lenses amplify any movement.

A rough rule of thumb is to set the shutter speed at least the same if not greater than the focal length of the lens.

for example;

 

Available light:

Available light may be so low that even at the widest aperture the shutter speed needs to be very slow, for example, nighttime when you may get to use the infamous 8 hour exposure.

Or the opposite situation where the light is so intense that the narrowest aperture may still require a fast shutter speed, for example, midday with high-speed film.

 

Tripods:

The tripod is a very handy tool whose main purpose in life is to allow the photographer to reduce shutter speeds.

It eliminates camera movement - allowing the infamous 8 hr exposure.

It can also be used with the 600mm lens to allow useable shutter speeds.

 

Artistic effect:

What if I want to have some blurred movement in my photo? Go right ahead - experiment.

If you know the theory and can predict what the result might be you won't waste film (much).

Or if you get the effect unexpectedly, you'll know why.

 

Film Speed:

I'll talk about this in more detail in a separate section.

 

 

Perhaps you are beginning to notice that everything is affected by everything else. This is certainly true.

The whole thing is one giant balancing act, weighing up many different factors, with that one ultimate goal - get exactly the right amount of light to hit that little square of film - the correct exposure.