No Free Lunch - 1

Welcome to the shortest how to do it lesson in photography you will ever find. It is not meant to be an expanded treatise, but more of a quick and dirty lesson.

The film negative is the most important part of the process, for without an image made in the camera (in traditional photography), you have no source material, and no prints can be made nor can any other image. So, we must be concerned with how to make the best possible negative. Fortunately, this is pretty simple and it only involves four things and their relationship to one another. Each choice affects the other and they all go together in a harmonious whole.

The items of concern are, in no particular order:

• The light available, which will represented for the purposes of this discussion by the sun.
• The film speed (sensitivity to light), referred to as the 'ASA' or 'ISO' number.
• The shutter speed (a measure of time), which can be divided into convenient units.
• The lens opening, which controls how much light the lens will pass to the film. The size of the opening is adjustable over a wide range.

 No Free Lunch - 2

Let us consider each of these factors in the order presented above.

1) The light that is available to expose the film can be adjusted before the picture is taken, flash can be added during the exposure, but the only thing that counts is the light that hits the film while the shutter is open. So, it can be said we cannot control the light, whatever hits the film hits the film. It is beyond our control, you can't turn the sun off, or unless the situation is complete controlled such as in the studio.

2) The speed of the film is fixed by the manufacturer. Though some adjustments can be made the speed is what it is and thus is more or less beyond our control.

There was a time when film speeds were mystical, hidden in an obscure corner of the film box. Now the film speed is included as part of the film name such as Kodacolor 100 or 200, T-Max 100 or 400 or Ektachrome 100 or 400. Each of these films gives us a different end product. (Kodacolor gives us negatives for color prints, T-Max is a black and white film giving us negatives for black and white prints and Ektachrome produces slides), and each of these films is available in a variety of speeds for different lighting conditions. The higher the number, the more sensitive the film is to light. Or, stated another way, a higher speed (number) film such as 1000 takes less light to produce a picture.

Film manufacturers have helped us a lot by telling us what films are good for with labels on the box such as 'general purpose', 'for sunny days', 'for low light or fast action'. These generalized terms help us to choose a film suitable for our needs.

What we have done so far is eliminate one half of the variables. We may now concentrate on the other options which will permit us to really control how the picture comes out.

 No Free Lunch - 3

3) The shutter speed controls how long the film is exposed to light. The length of the exposure can be related to results you have probably had or seen in pictures, namely blurring. The longer the exposure, the more likely there will be blurring. So, in one sense, we can think of the shutter speed as a motion control. A longer shutter speed such as one second will give more blurring than an thousandth of a second. By controlling the shutter speed we can use it to freeze motion or provide a sense of motion by allowing some blurring. In extreme cases, the picture is so blurry that it is not usable. So, we can think of the shutter speed as a 'motion control'.

Shutter speed commonly run in the following sequence: 1, 2, 4, 8, 15, 30, 60, 125, 250, 500, 1000. These stand for fraction of seconds: 1/1 (full second), 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000. The bigger the number, the faster the shutter speed, or the smaller slice of time it represents. You will note that each shutter speed is about double or one-half the speed on each side. The division will relate to our next discussion.

 No Free Lunch - 4

4) The lens opening controls the amount of light the lens passes as well as the depth of field, that is how much of the subject, from front to back is in focus or appears sharp. Sharpness is a relative concept in this instance. If the lens is focused at 10 feet, the only thing that is truly sharp is the plane that is 10 feet from the film and parallel to it. Everything else from front to back is relatively sharp.

At the plane of focus, a point of light on the subject is registered as a point of light on the film. As the point of light moves further from the plane of focus, it grows larger, eventually becoming a fuzzy dot, which our eye can tell is a fuzzy dot. At some distance from the subject things just look fuzzy. It is at that point we say the depth of field has ended. The reason that there is such as thing as depth of field is that the eye can see things about 1/40" in diameter. When the size of the out of focus point of light is larger than 1/40" it is visible, when smaller, it is not. So, 'depth of field' tells when the size of the fuzzy dot is 1/40" or larger.

It is easy to see the effect of depth of field in may photography books demonstrated by setting cards at various distances and noting when the become fuzzy. More cards are sharp as the depth of field increases. You may also see the effect in outdoor photos by noting that the grass ahead and behind the subject gradually blurs.

How can we make depth of field work for us? First, we must understand how to control it, which leads to a bit of confusion. Look at most lenses and you will see a series of numbers on a ring: 2, 2.8, 4, 8, 11, 16, 22. A given lens may have some or all of these. The bigger numbers mean the lens is passing less light, and the smaller numbers pass more light. The bigger numbers give more depth of field and the smaller numbers less.

Going from a smaller number to the next larger number cuts the light in half and going from a larger number to a smaller number doubles the amount of light. This relates to the discussion of shutter speeds and their doubling or halving in controlling exposure.

 No Free Lunch - 5

Well, it all sounds pretty confusing, but now it gets much simpler. So how does it all relate to making the picture you want?

First decide how much light you are likely to have when you are taking the pictures. If you will be outside on a sunny day, choose a film with a lower speed (ASA, ISO), such as 100. If you expect the light to be fairly dim, or just don't know, cover your bets, choose a film with a higher number such as 400 or even 1000. You will have more grain, but the extra speed may mean you can get a picture otherwise unobtainable...do you want the picture or not???

Second, determine how your subject will be moving. Will you be shooting football, basketball, swimming or tortoises in sub freezing weather? Obviously the speed of action varies a lot from second to second and in the case of the tortoise, not much at all. The speed of motion will determine our choice of shutter speeds. Another factor in all this is how steady are you? Did you slam down four or five cups of double strength cappuccino this morning or are you likely to be excited? If either of these are considerations, then choose a route to help with faster shutter speed (faster film, add light etc.).

As a general rule, choose a shutter speed of 1/125 sec. or faster. This will usually insure that blurring caused by your movement will be minimized.

Is it important that you have a great deal of depth of field (a lot of stuff in focus)? If so, then you will need to:

• Use a slow (longer) shutter speed.
• Add more light.
• Use a tripod, monopod or other support (the hood of a car or tree).
• Use a higher speed film (it always seems to pop up, doesn't it?).

Doing any or all of these will permit you to close the lens down (smaller hole, larger number) to increase depth of field.

 No Free Lunch - 6

So, it all comes down to making choices, but armed with the knowledge of what each of these compromises does to the final result, you can go forth as a wise and knowledgeable photographer confident that you have chosen the materials and equipment to meet any photographic challenge...that is if you made sure the batteries in the camera were OK.

This chart helps in making choices due to the effects of the four variables we have discussed.

 No Free Lunch - 7

In short you can stop motion or have a lot in focus, but not both. That is why it is necessary to make a choice as to which factor is more important, stopping motion or having a lot in focus. Generally, stop the motion (usually your own motion) to prevent blurring. Let the depth of field fall where it may, because nobody likes blurry pictures.

Two golden rules never before divulged in the history of photography!!

1) Shutter speeds change by a factor of 2! Lens openings vary by a factor of 2! If you have a shutter speed of 1/125 sec @ f/11, it is the same exposure as 1/250 @ f/8. You cut the time in half but doubled the light going through the lens. For each click of the shutter speed dial, move the lens opening the opposite way an equal number of numbers (some lenses have what are called 'half stops'). What has changed is that at 1/125 @ f/11, you have greater depth of field, but may not be able to stop some motion. At 1/250 @ f/8, you will stop faster motion, but the depth of field will be reduced.

2) If you are outside and your meter battery fails: Determine the speed of the film in your camera (100, 200, 400). Set your lens to f/16. Set your shutter speed to the next lower number that approximates your shutter speed (100 = 1/125, 400 = 1/250). This is known as the "SUNNY 16 RULE", and can be used as a starting point in an emergency. If it is cloudy, go to f/11, f/8 or lower depending on your assessment of the light available. Example: 400 speed film, bright sun, set lens at f/16 and shutter speed at 1/250. 100 speed film, bright sun, set lens at f/16 and shutter speed at 1/125 or 1/60.

This is in fact, how film speeds are determined, so it has to work.

I hope this will clarify some of the questions you have about photography. Explaining some of the concepts is a difficult task, especially doing it simply. I welcome you comments and suggestions on parts, which are less than clear. Revision will be an ongoing task.

Permission is hereby granted to reproduce this work in any form, provided credit is given for authorship. Please direct comments or questions to:

Roger G. Christian University Camera

email:univcamera@aol.com

4 South Dubuque St.

Iowa City IA

52240

Phone: 319-337-2189

Fax: 319-337-2180