The shutter speed is how long the image sensor (or film) is exposed or is receiving light. This is measured in fractions of a second.

On manual film cameras the speed increments are: 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000 (maybe higher).  Each step is double the amount of light or half of the amount of light. For example, 1/250 of a second is twice as fast as 1/125 of a second. You will be letting half as much light reach the sensor at 1/250 of a second than 1/125 of a second. 1/60 is slower than 1/125, so it lets in twice as much light.

On film cameras the shutter is a curtain with a gap in it that runs across in front of the film plane. You can see it happen if you take your lens off, set your shutter to a really slow setting like ¼ of a second and “shoot” a picture while looking into the guts of the camera body.

Digital cameras allow you to shoot at many more speeds. An average digital camera can have 1/4000 as its top speed. The increments are ¼, 1/6, 1/8, 1/10, 1/13, 1/15, 1/20, 1/25, 1/30, 1/40, 1/50, 1/60 and on up the scale. There are more speeds available with digital cameras. They have two speeds, placed in thirds, in between the old film cameras full stop (and half stop) capabilities. So now every step in between is changing the setting by one-third of a second. I know! I am trying to keep it simple!

Remember from the aperture discussion last week that the aperture steps are also in thirds on digital cameras so they work proportionally together. The right combination of shutter speed and aperture will yield a correct exposure.

If you Google digital image sensors, you can see pictures of what they look like. No longer are there moving parts to see as it is now a digital chip.

How would you decide what shutter speed you want to use when taking an image?  One thing to consider is what kind of action or motion you are attempting to capture. If freezing the action of a baseball pitcher is important, you need a pretty fast shutter speed to record that action the way you want. That would be 1/1000 or even higher. Experience and practice will show you exactly what speeds will stop how much action.

You can use a slower shutter speed to photograph a flower in the garden on a still day or an object that does not move.

For a correct exposure, the balancing act of which shutter speed works with the aperture you have selected or what aperture works with the shutter speed you have selected. This series of decisions depends upon what your priority is for the picture and the final outcome you desire. Sometimes the shutter speed is the important number to pick first, sometimes the aperture is more important if you want a certain amount of depth of field.

Get out your camera and go practice! The awesome thing about digital is that it does not cost anything to shoot and see how you are doing, so go crazy.

About Barb 
Barb Gordon, of www.BarbGordonPhotoCoach.com, is a Master Photographer, Photographic Craftsman, and Certified Professional Photographer with the Professional Photographers of America (PPA) to which she has belonged since 1984. She is a nationally published and award winning photographer, entrepreneur, speaker, and author including being published in the prestigious PPA Loan Collection 2006, PPA Showcase 2003, twice named Iowa’s Top Ten Photographer of the Year, and 2010 Iowa’s Master Photographer of the Year