Shirley Says ~ Part Three: ISO and shutter speed

This is the third segment of Shirley Says at 27 & Counting. You can read Shirley’s prior photography tutorials by clicking here and here. Thanks for visiting and we hope you enjoy this lesson on shutter speed and ISO settings …. take it away, Shirley!

Visit Shirley’s photography website by clicking HERE.

What is shutter speed?

The length of time that your camera’s shutter is open is called the shutter speed. It is measured in fractions of a second, or the amount of time your camera’s sensor is exposed to (“sees”) the object being captured in a photograph.

In simpler terms, think of the shutter as a curtain. The “curtain” opens and closes allowing light to hit the camera’s sensor. When you press the button to take a photo, you are essentially opening and closing the curtain. The noise you hear is the curtain being opened and closed. Amazing, huh?!

Consider this when determining shutter speed:

  • The longer the curtain is open, the more movement you capture.
  • The faster you open and close the curtain, the less movement you capture.

A fast shutter speed allows less light into your camera, whereas a slow shutter speed allows more light. Keep this in mind when manually adjusting your settings (i.e. aperture, shutter speed, and ISO) because shutter speed affects the aperture and ISO. Shutter speed variations are most helpful when capturing movement. Slow shutter speeds will have a blur of the moving object and a fast shutter speed keeps the object in focus.

When photographing children, it’s recommended to use a high shutter speed due to them moving quickly. However, if you want emphasize their action, choose a slower shutter speed.

I think it’s important to mention here that the use of a tripod is crucial when selecting shutter speeds for movement. There is a BIG difference between an object’s movement you’re trying to capture in an image and a human’s movement when holding a camera and taking a photograph!

What is ISO?

ISO measures how sensitive your image is to noise, or light. The higher the ISO, the more sensitive your camera is to light and the image will have more noise (light) in it. If the ISO is lower, the photo will have less noise (light) in it. 

If you find yourself in a situation with bright light conditions, you can use a lower ISO setting. However, if you’re in a building or outside on a cloudy day, you will need a higher ISO setting for increased noise (light) in the photograph. Let me add that cameras have come a long way and so many of them now are really excellent at having as little noise as possible at high ISO’s. However, some of our DSLR cameras are capable of REALLY high ISO settings and, of course, there will be noise…but, at least you can get the shot!

Remember, shutter speed affects aperture and ISO ….. set accordingly!

Things to conside when adjusting ISO settings:

  • Use an ISO of 100 or 200 when taking photographs outside in sunny conditions
  • If the sky is overcast or taking photographs in the evening, use an ISO within the range of 400 to 800
  • At night or with conditions of very low light, set your digital camera ISO to 1600


Nicole says … I hope Santa brings me a tripod!


Until next time, happy shooting!



Don’t forget about the Current Giveaway at 27 & Counting ….. click HERE to enter for a chance to win a $25.00 gift card to Initial Outfitters hosted by Jan @ The Diamond E. Good luck!



  1. Another valuable post, thanks Nicole and Shirley.
    Hope Santa bring you and me both a tripod!


  1. […] You can read Shirley’s prior post by clicking here, here, and here. […]

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