Opportunities to improve

"Ask and it will be given to you,

seek and you will find,

knock and the door

will be opened to you."

~Matthew 7:7 NIV

Back to basics:

What does ISO really mean?

I get a lot of questions about this "photo stuff", so here are a few tips.
The letters ISO can scare a beginner off! Thus begins the challenge to learn. Along with the learning, comes the opportunity to really improve the quality of your photography. I have found in my experience that the same principle applies to digital as well as my old film camera. That seems to be the best way of understanding ISO to me. Just think of ISO as "film speed". In the digital camera then ISO is your camera sensors' sensitivity to light and how it affects your images.

Keep it simple:
If I have my camera set for ISO 100, simply put, I have 100 opportunities or possibilities to gather light. When I change the ISO setting to 200 I now have 200 opportunities to capture light. The sensor can now gather the light that comes through the lens twice as easy, and make an image.

If we continue to compare ISO 100 and ISO 200, with the lens aperture (opening size) set at f/5.6, the same volume of light will be coming through my lens at each setting, but at the ISO setting of 200, I will record the image the quickest, since I have have twice as many opportunities to gather the light. So, the more I need light, I can compensate for the need with a higher ISO setting.

Then shutter speed comes into play! Why is shutter speed important? If I am trying to photograph a mushroom on a cloudy, overcast day: With a setting of ISO 200, 1/250 sec. is pretty close, but for ISO 100, I will need more time, or 1/125 sec. ~ a longer exposure is needed to capture more light.

You can do a simple learning exercise by writing down the indicated shutter speeds required at different settings. Try setting your ISO to 200, and your aperture to f/8. Focus at a subject and adjust your shutter speed until a correct exposure is indicated. (Usually the indicator lights stop blinking!) Write down the shutter speed. Next adjust up to ISO 400, keeping the aperture at f/8, and point the camera at the same subject. Now your light meter is indicating a different shutter speed for a correct exposure. Write it down. Do the same procedure at ISO 800 and again for 1600.

What have you noticed? When you change from ISO 100 to ISO 200 your shutter speed changed: from 1/125 second to 1/250 second or perhaps something like from 1/160 sec. to 1/320 sec. See the pattern? Each shutter speed is close to, if not exactly half as much as the one before it.

So, changing from 1/125 sec. to 1/250 sec. is half as long the exposure time. When you set the ISO to 400, you went from 1/125 sec to 1/500 sec.

Just as each halving of the shutter speed is called 1 stop, each change from ISO 100 to ISO 200 to ISO 400 is considered a 1-stop increase (an increase of opportunities to gather light).

You can do this same exercise by leaving the shutter speed the same, for instance at 1/125 sec., and changing the aperture until a correct exposure is indicated in the viewfinder; or, if you choose to stay in auto exposure mode, select shutter-priority, set a shutter speed of 1/125 sec., and the camera will set the correct aperture for you.

Yes, new opportunities exist. Try "knocking on the door" of a new way of doing photography ~ you will just be as amazed as I have been! Maybe we will discuss this basic stuff again! My best advice: try it, and don't quit. It soon will become second nature to you!

For now ~ Love to all, Norm

http://www.nicholsonphotoimages.com/
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