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Photo Friday – How Your Camera Works

February 1, 2013

So, you got a new DSLR for Christmas and you’ve finally had time to get it out of the box.  Or, you’ve had one for years but everytime you switch it over to manual, you’re bombarded by a flurry of numbers and words that don’t make sense: ISO, f-stops, shutter speeds, aperture, white balance, exposure, etc…  Eventually you get frustrated and switch it back to fully automatic.  The truth is, those words and numbers are confusing if you try to understand them all at once.  But just knowing how a camera functions will help you a great deal to understanding those words, and what they can do to improve your photography.

Let’s start at the very beginning, shall we?  The first camera ever made was a pinhole camera.  It was essentially a box with a hole poked in one side, a flap of paper that could cover the hole or be removed to let light in, and a piece of photo sensitive material on the inside of the box, opposite the hole.  Pretty simple, right?  Your camera operates in much the same way, you just have more control because you’re able to adjust all those variables.

1) Aperture – aperture is how big the hole is in your box.  A bigger hole will let in more light.  A smaller hole will light in less light.  Your camera lens operates in such a way that it’s able to adjust the size of the hole that lets light in, and it’s measured by an f-number.  {Now here’s the tricky part – a lower f-number is actually a wider opening.  So, f 1.8 is a much wider opening – or bigger hole in your pinhole camera – than f 11}

2) Shutter speed – shutter speed is how long the flap of paper is held open to let the light in.  A longer shutter speed lets more light in.  A shorter shutter speed lets less light in.  {Here’s the tricky part – your shutter speed will generally show up as a number like 100 or 250 or 500.  This actually means 1/100 of a second or 1/250 of a second.  So a higher number shutter speed is a faster shutter.  Note: if you find your shutter speed showing up as “5 or  1″5, that means you’ve delved into numbers that are no longer a fraction of a second, but are a second or more.  If you’re photographing with these settings you’re going to need a tripod or your pictures will be blurry.}

3) ISO – how sensitive the photosensitive material is.  In the olden days it was film – a plasticky strip that had emulsion crystals on it.  These days digital cameras have digital sensors, but it’s the same idea.  A higher ISO is more sensitive to light (meaning the sensor doesn’t need as much light to hit it in order to obtain the proper exposure), and a lower ISO is less sensitive to light.  So, if you’re outside on a nice, bright, sunny day your ISO will probably be 100.  If you’re in a dark room, your ISO will be higher because you need the sensor to be more sensitive to the small amount of light you have, so it will be more like 600, 800, or even 3200.

These three tools work together to provide your picture with the proper exposure.  Let’s say you take a picture that is properly exposed and your settings are ISO 200, f-stop (aperture) 5.0, Shutter speed 500 (or 1/500 of a second).  But you decide you want to open up the aperture and let more light in.  As you open up the aperture to 2.0, you let more light in.  This means you also need to make a change to the shutter speed so that it is letting less light in.  Your shutter speed needs to increase to 3200 (or 1/3200 of a second) to maintain the exposure.  Don’t worry about the numbers right now – I’ll show you a chart next week with the f-stops and the shutter speeds.  Just get used to the idea that aperture and shutter speed have a converse relationship – if one goes up, the other one has to go down; and vice versa.

This week as you take pictures, pay attention to the numbers the camera flashes at you and remind yourself that the f number means how wide open the lens is, and the shutter speed means how long the curtain stays open.  Happy photogging!

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4 Comments leave one →
  1. February 1, 2013 1:04 pm

    This is so great, thanks for sharing!
    Do you have a fave book to use as a guide as well?

    I have a dslr, using it for a couple years, but still stuck in normal mode.

    • Lisa permalink*
      February 2, 2013 9:18 am

      Hi, Katie. I think the best book for learning the basics is “Understanding Exposure” by Bryan Peterson.

  2. February 1, 2013 9:13 pm

    You’re writing this just for me, aren’t you??? I so appreciate it. It’s hard for me to really “get.” Keep writing and I will keep reading…and start paying better attention to numbers…thank you!

    • Lisa permalink*
      February 2, 2013 9:19 am

      I’ll keep writing, and you keep reading, and you’ll get it. Just you wait!

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