The need for speed

Thank you the two people who read my blog on Christmas!  I have no idea who you are, but thanks to google tracking data I know two people read my blog.  Woohoo!!

Ahem, I mean, it's time to examine the last point in our exposure triangle.  Speed...well the speed of the shutter.  This is perhaps the easiest point in our triangle to explain.  Shutter speed is exactly as it sounds...the speed of how quickly the shutter closes from the time your press the button to take a picture.  Easy.  Done.  Next.  But like all things in photography it's simple in it's fundamental aspect but, oh my, how it can affect the image you are trying to capture.  Shutter speed helps you get that silky smooth affect on water, it can capture geese in midflight, and anything in between.  

I like to think that when I take a picture I am capturing a moment in time.  A slice of life as it flows all around all of us.  When you take a picture you have the option of determining how much of the moment you want to capture.  What is the final image you have in your minds eye and how can you use the camera to get that?  That's the question I ask every time I take a picture.  Admittedly I don't succeed in getting the camera to create what is in my mind all that often, but that's the point of learning.  I know what your thinking, I'm rambling on about all this and it doesn't have much to do with shutter speed.   Don't worry, I promise a point is coming soon.  Imagine I want to take a picture of a pristine waterfall and have a silky smooth image of water flowing over the rocks.  Then to capture this longer slice of time (see I told you I was getting to a point) I would need to have a longer shutter speed.  Depending on the time of day or amount of light, probably in the area of 5 to 10 seconds.  Longer if it's early in the morning or near dusk.  The longer you keep the shutter open the smoother the water will be.

Now let's reverse that.  Say I want to get a picture of a dog running right at me, grinning ear to ear.  I want to capture that brief moment of his paws in the air and tongue wagging.  I would need to have a pretty quick shutter speed for that image.  In the neighborhood of 1/1000th of a second.  When the shutter is set that high I'm essentially stopping the action.

It really all depends on the type of image you are trying to create.  One of the things I really like about photography is when I try to figure out how to get what my mind is thinking to match what shows up on the display screen.  Sometimes it's easy, sometimes it's really hard.  

Now to bring it all together.  The exposure triangle is all about capturing light to get the image you are looking for.  Light dictates everything.  If it's a bright sunny day you are not going to be able to keep the shutter open for long periods of time without overexposing your image.  If it's a cloudy day or you are shooting at night you will need to keep the shutter open longer to allow more light in.  However, you won't be able to stop action.  The amount of light you can let in allows you to get whatever image you are trying to achieve. 

Let's use the example of the water flowing over rocks.  If I want that silky smooth look I know I'm going to have to keep my shutter open for a long time.  So the first part of our triangle is set.  Long shutter time.  Now how much light is this going to let in?  You've reached the waterfall, you know you need a longer shutter speed but it's pretty sunny.  So how do we keep the image from over exposing?  Come back when it's not as bright?  Well yes, sure, but you may not be able to do that.   So you reduce your ISO setting down to the lowest number you can.  Still too much light coming in?  What is your aperture situation?  Are you wide open at f3.5 or even wider?  Remember that aperture directly controls how much light is hitting the sensor, so close that diaphragm up and set your aperture to f22 or something like that.  Now you have reduced the amount of light drastically.  You press that shutter button and viola you have an image of water flowing smoothly over rocks.  

I realize all this is the beginners view of our triangle.  There are many many ways to get a properly exposed image.  And to toss in a wrinkle, there are times where you want to purposefully over or under expose an image.  But this blog is an exercise in learning about photography and seeing how much knowledge I am able to retain and pass on to the two souls who read my blog on Christmas day.