EXPOSURE DETERMINATION


For many photographers, exposure determination is the most frustrating aspect of photography. There are many reasons for this frustration, which just makes things worse.  First, you spend hundreds, perhaps thousands, of dollars on a camera and the exposures don't seem any more accurate than your spouse's $9.95 point-and-shoot.  You've read the manual 14 times and still can't decide what to do.  You set the film speed correctly, and tried every exposure option that the camera offers -- programmed mode, aperture-preferred-mode, shutter-preferred mode, manual mode, fill-in-flash mode.  You've tried various labs.  You've even tried different films with no luck.  Some exposures are good but others of just plain bad.  

A main reason for this frustration is the "mystical" nature of exposure. Everybody has their own special approach. Even the "authorities" can't agree on anything. If you read a dozen books on exposure, you'll get two dozen ways to do it. We end up with "schools of thought" about exposure that are reminiscent of the Greek philosophers of the Golden Age -- everyone coming up with a different scheme, and so busy competing against each other that they never have time to test their theories. What should be (and can be) described easily and tested scientifically is covered with myth and misinformation.

I encourage all of you NOT to believe any of what you read in this section. The most important aspect of exposure is that every person's exposure must be individualized. The reason is that every person's photographic situation is different. There are many different aspects of correct exposure. To name just a few: type of camera, type of meter, subject contrast, type of film, type of developer, developer dilution, developer time, type of enlarger, type of paper, type of developer, developer dilution, developer temperature. The list goes on and on, but you get the point. There are so many conditions affecting exposure that everyone's exposure must be different. Any two photographers exposing for the same scene at the same time, must use a different exposure if any of the above conditions are different -- and they will be.  

That's the bad news.  The good news is that exposure is like climbing a mountain.  You don't have to go to the top to get a good view, but the higher you go the better the view will be.  We'll start with the basics of exposure and work our way up.  You can turn around at any point -- when the view is good enough!

Today's cameras are a boon to photographers for they have removed the drudgery from picture taking. Just twenty years ago, most cameras were large, heavy and much more difficult to use and understand. In fact, one reason for the recent gains in the photography industry is the ease with which pictures can now be taken. Besides being smaller and lighter, modern cameras frequently incorporate such features as automatic film loading, automatic ISO speed setting, automatic film advance and rewind, automatic focusing and automatic aperture and shutter speed selection. Little is left to do for the photographer who wants quick, easy pictures. In fact, there is even a camera which talks and tells you when you are probably making a mistake. There are even cameras that can automatically correct the composition of pictures; someday this may be a common feature.

These automatic systems, although convenient, are not without limitations. They are designed to operate correctly under a set of common, programmed conditions. If these typical conditions exist, the resulting slide or print will display fine quality, but under more unusual circumstances the camera may produce unacceptable results. For example, automatic focusing cameras generally give excellent results, but objects that are in the foreground, such as trees, fencing, or even window glass can lead to out-of-focus pictures. Similarly, automatic film advance normally is appropriate, except when a double exposure is desired. Some cameras have incorporated manual overrides of their automatic features in an attempt to solve these problems, but this ends up complicating the camera and drives up the price.

Similar problems underlie cameras designed to simplify exposure settings for the photographer. These automatic and semi-automatic cameras will produce correct exposures under average circumstances, but the shutterbug all too frequently encounters uncommon lighting conditions, such as sunsets, night scenes, and foul weather. In fact, scenes with unusual lighting are what many photographers seek out for dramatic effects.  Unfortunately, these unique lighting conditions can fool even the most expensive and sophisticated meter. All too often the photographer incorrectly concludes that either the camera is broken or that photography is just too complicated to master. In fact, when a picture is over- or under-exposed the camera is merely doing the best it can given its limited set of instructions in an atypical situation. As this becomes clear the mystery and confusion so often associated with photographic exposure is dispelled.

Many photography books include a few pages pertaining to exposure, but the brief explanations normally are limited to the specific topic covered in the book --such as close-up photography --and generalizing this information into other areas of photography is difficult or impossible. Here we explain in detail how camera metering systems often lead to unsatisfactory results and how these problems can be avoided. It can provide the reader with sufficient knowledge to calculate exposures for extremely unusual situations. On the other hand, because this material is in-depth it cannot be approached casually. It is not intended for the person just starting out in photography, but rather for the serious photographer who already has a basic knowledge of the area and wants to improve exposures or expand into new areas.

We will begin with the basics and then expands into more unusual circumstances. Section A describes in detail how meters work as well as their basic limitations. Section B examines various methods used to compensate for these meter limitations for both automatic and manual cameras. Section C explores exposure problems that lie outside of the meter system and how these lead to exposure inaccuracies. Section D discusses a variety of unusual circumstances where metering is difficult and special precautions are needed. Section E details ways to obtain optimum results on a consistent basis. Finally, Section F contains a variety of appendices that are helpful in solving exposure problems and in buying exposure equipment.

Lastly, we provide a variety of exercises which are designed to clarify concepts as well as to determine the idiosyncrasies of your equipment under a variety of conditions. Carefully following these tests in a step-by-step fashion will ease the assimilation of the more technical parts of this material. Whenever performing any of these tests it a good idea to keep copious notes of how you proceeded so that errors can be easily identified and corrected.

We'll start by taking a look at how meters work.  


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