Just between you and me, exposure had always been the most intimidating and problematic part of photography for me; especially when I first got started. I still feel less than a pro at setting for exposure, but I certainly understand it more now than I used to. At least now I know when I approach a scene that I can get pretty close on the exposure; I know basically what my camera is going to do. What made the difference for me?
Good teachers – I have read much here at NPN, asked many questions, and looked at lots of images. I also watched John Shaw’s video on exposure. I don’t feel that I could not have used just one of these resources to progress; I have used all of them combined. I hope that these thoughts will help you out. Just remember that this method that I will describe here and the activity that we will go through is just one way of thinking. I am certainly not a pro, but I hope that maybe my perspective can help a little bit.
Guy Tal recently stated in a thread in the NPN Nature photography discussion forum on photography definitions “Exposure is simply the amount of light hitting the film/sensor. Shutter speed and aperture are a means of controlling exposure but do not make up exposure, light does”. Guy went on “Film speed is a way of quantifying the film’s sensitivity to light. A faster film will need less exposure in a given situation than a slower film.
Film speed needs to be taken into account when deciding on the appropriate exposure?rdquo; The illustration below shows how a film will interpret a given scene. Slide film has a five-stop latitude. Areas that are too dark (to the far left of the illustration) will appear blocked up where areas that are to light (to the far right) will be blown out. This is why it is important to know how to determine the exposure. In most scenes there will be some area that is outside of the latitude of the film.
My following comments will assume that the film speed or ISO sensitivity has been set in your camera or meter. This will leave us basically two unknowns of the shutter speed and lens aperture to set to decide upon our exposure settings.
Let’s try a little bit of an activity to illustrate exposure settings and how your camera meter works. Print this article and sit down somewhere with your camera. I found it easy to sit on the couch in my living room since the light was easily controlled and the range of light was not very drastic. Once sitting down, take your camera and set your meter to ‘spot’ metering and the mode to ‘manual’. (You may also want to do this without film in your camera, unless you want some pictures of your entertainment center.) I also find it helpful to set the aperture and to leave that constant for this exercise.
Once you are comfortable and you have your camera’s mode, metering, and aperture set; start pointing your camera at different things as you look through the viewfinder. Your camera’s spot meter should take whatever is in the center of the lens and meter it. On my Nikon, I have a visual indicator of this meter in the lower right of the viewfinder; I would bet that most manufacturers would have something similar in your make and model. To illustrate the principle of a mid-tone, point the lens at something and turn the dial to set the shutter speed. Turn this dial until the meter shows the indicator in the middle of the meter. The tone of the item now being metered will be made mid-toned. Mid-toned is 18% on a gray scale, or the equivalent mid-tone of the color that is being metered. All other tones in the image in the viewfinder will be rendered based on this reading. Now point the lens at something lighter or darker and notice that the meter indicator shows to the right or the left of center. Changing the shutter speed on one of these other tonal values, until the visual indicator of the meter shows in the center, indicates that this current tone will be rendered mid-toned at this shutter speed. Is this beginning to make more sense? Let’s talk in terms of a specific image.