Photography - What You Need To Know

First of all, let's identify what a camera is, and what it does.  In essence, all a camera is; is a light-tight box with a lens and a recording medium.  The lens's job is to direct otherwise random rays of light into the box and direct them with precision onto the recording medium.  In today's world of photography, it is far from being this simple, but your camera still does the same basic job.

So, if we have light, a lens, a digital sensor or film, and a light-tight box; we are able to make a photograph.  Although this is true in its simplicity, it is actually much more complicated than this, as I'm sure you already know.  It is more complicated because there needs to be some control over how much light exists in the scene, how much can enter through the lens, how long it takes to get enough of it, and how sensitive the sensor is.  In this problem exists the four most basic things that need to be measured and balanced in order to produce an acceptable exposure, and are therefore the topics of our next four lessons:

Shutter Speed
Aperture
ISO Ratings
Amount of Light in the scene

The effects you get from your shutter speed are varied depending on some additional factors: distance of subject from camera, focal length of lens, speed of subject in relation to the shutter speed, and the direction of the subject relative to the camera.  All of these things really only affect one thing though: The amount of distance the subject travels across the frame of the photograph while your shutter is open.  Tattoo that somewhere (you don't need to tell me where).  Just make sure you remember this because it is vital to understand.

Let's disuss how these principles play together to create your desired effect...

Distance from the subject is also very dependent on the Focal length of the lens because with a telephoto lens, the object is much larger in the frame at the same relative distance.  Therefore, if a subject is 200 feet away and you have a 35MM lens, there is little perceptible movement.  If the same subject at the same distance is photographed with a 600MM lens, the movement will seem much greater.  This is really the same as your own eyes.  When you see an airliner in the sky, it doesn't really seem that a few hundred miles per hour is very fast; but a car passing right by you at 45mph seems very quick.  These are extremes of course, but hopefully it demonstrates the point.

Here are some examples:

In this one, I am about 40ft from the tree with a slight breeze blowing.  Image on the left is at 35MM, 1/40s, f/22, ISO200.  Image on the right is at 200MM, 1/40s, f/22, ISO200.


Here, I have moved in much closer to the tree.  I am now only about 3ft away from the trunk.  Again, on the left is 35MM, and on the right is 200MM; both at 1/40s, f/22, ISO200.


There were some other things to consider though, right?  One of the other points I mentioned was the Speed of the subject relative to the shutter speed.  Although 1/60s may be fast enough to stop the action of a walking subject, a race car will be a complete blur of streaked color.  You may need upwards of 1/1000s to freeze an Indy car as it races past your spot in the stands.  Again, it is dependent upon how far the subject moves across the film plane while the shutter is open.

For example:

Here, the boy on the left is just getting ready to take the ball from a pass, the one on the right is already running trying to intercept it.


The other thing we need to consider is the Direction the subject is moving relative to the camera.  If a motorcycle is coming straight at you [the photographer], there will be little movement across the film plane.  Alternatively, if it is moving perpendicular to your camera, it will travel across the film plane while the shutter is open and appear blurry.   One method to making a sharp photo when the subject is moving quickly across the film plane is called 'panning'.  Follow your subject with the camera while pressing the shutter.  Remember to follow through the entire motion.  Sometimes this is easiest if you have a continuous mode on your camera, because you can hold the shutter button down and keep panning while the shutter is exposing frame after frame.  Realize that this is not always the best method of getting 'the' shot because your continuous mode may miss the moment of peak action; but it may work to help you practice at following through.

Example of panning:

Sorry for the delay in this thread, folks.  My family and I have moved into a new home, and although there's still a lot to do, I think I should have a little more free time now to keep working on this.  I appreciate all your patience and especially your willingness to participate.

Our next lesson is about aperture.  The aperture is a factor that describes the diameter of your lens opening relative to its focal length.  If the shutter speed describes how long it takes to fill a glass of water, then the aperture is the factor that describes how wide open the faucet is.  An aperture is described as an f-number with the convention of "f/x".  F-numbers are arranged in accordance with the mathematical factor of the square root of 2.  Although it's not intrinsically important to understand all the mathematics involved in aperture designation, I am going to explain two things; one to help you remember your aperture scale, and the other to help you understand what's really happening in a particular lens.

First, what does the square root of 2 have to do with anything.  Well, it equals approximately 1.4.  What I'm saying is this, if I could tell you only two numbers that you needed to remember when determining aperture scales, would you be interested?  Well, guess what, there are only two numbers to remember.  They are the numbers 1 and 1.4.  These two numbers can be doubled in an alternating sequence to give you your aperture scale from 1 to infinity (if you have that much time).  Let's try it, starting from 1 and 1.4, here is the values in the alternating scale I am describing.  The series starting with 1 and doubling will be shown in blue, and the series starting with 1.4 and doubling will be shown in red:

1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, 44, 64... and so on.

Cool, huh.  OK, so the second point with the mathematics is this; the value is a calculated factor that takes into account the effective focal length of the lens.  The convention of the 'f' and the divided by '/' symbol is no accident.  The 'f' stands for focal length (it actually stands for some French word, but it means the same thing), and we can actually divide it by the value to get the actual lens opening.  So, a 50MM lens set to f/2 has a lens opening of 25MM.  50/2 = 25.  I feel its important to realize this because this is the same reason why depth of field is so different with the same f-number on a different focal length lens.  We will get into depth of field more later, but for now, just realize that it is controlled by many factors, one of which is the lens opening or aperture.

So, the primary use of shutter speed in your creative toolbox is to show motion.  The primary creative use of aperture is to control depth of field, or the amount of 'depth' is in focus in your image.  Depth of field is determined by several other factors, however, so instead of doing the regular assignment where everyone gets to go out with whatever lens and scenario they want to produce varying photos of controlled focus.  I'm going to restrict everyone a little for the time being.  I want this lesson to be solely about depth of field, so in order to temporarily squander the discussion of all the other depth of field controls available to you, I am asking that we all go out and take some photos with a set standard on certain criteria.  Hopefully this doesn't stifle your creativity too much, in fact I hope it helps by giving you something to overcome with your creativity.

OK, here are the guidelines.  You have to use a 50MM lens or the focal length equivalent with a zoom.  This still leaves room for subjectiveness with different sensors, but let's go this route for now and hopefully we see a certain amount of consistency to base our experiences off of.  I am also going to determine the two aperture settings we will be using, f/5.6 and f/16.  This is, again hopefully to maintain a certain amount of consistency and to allow for people with all levels of lenses to participate.  Your main subject for the image with the aperture setting of f/5.6 is to be ~4 feet from the camera.  For the image with an  aperture setting of f/16, the subject range should be no closer than three feet and can be as far away as infinity if you can see that far .

OK, so I know this is different than anything you've probably ever seen in any class or course, but I really want to spend some time later on about depth of field specifically, so I don't want to get too confused.  Aperture is only one element used to control depth of field, so we want to see to what extent it will affect it.  Also, while you're shooting, notice the effect on your shutter speed.  You will almost always have to choose one or the other as your primary creative tool for a given photograph because the other one will become the tool used to obtain proper exposure.

Well, go take some photos and post them HERE so we can discuss them again.  Thanks in advance for your support and participation.  Next we see how ISO will affect our exposures...

Until then,

Travis Minnig