With digital, I always shoot in automatic and the camera does everything by itself. Can I change something and add something of my own? [6/8]
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With digital, I always shoot in automatic and the camera does everything by itself. Can I modify something and put something of my own in it?
Before answering this question, a couple of things need to be said about the images you find around. The first is that there are many “well-made” photos, but there are also many simply “taken”.
The second is that good photographers take photos exactly as they want them, not “whatever comes,” although many think otherwise… We will talk about framing at another time. For now, however, let’s see how to take a photo manually, that is, by controlling some parameters to obtain the desired effects.
For an image to be recorded, whether on traditional film or in digital format, light is needed, and not coincidentally the word photography means “writing with light.” Now, making a very simple comparison with the human eye, we could say that a camera is structured a bit like it, even though obviously far more complex things happen in our eye than in a camera.
Depending on lighting conditions, the iris, shaped like a diaphragm, dilates or contracts the pupil to regulate the amount of light entering the eye; then the image passes through a lens, which in the eye is the crystalline lens, and is finally fixed upside down on the retina, that is, on our film or microchip.
The diaphragm
Just like in the eye, when we capture a very brightly lit scene we will have to close the diaphragm more to avoid too much light hitting the emulsion or sensors, thus making the photo “burned out,” while to record a dark scene it will be necessary to open the diaphragm blades fully, otherwise our image will be dark.
The diaphragm also allows us to regulate the “depth of field,” that is, to blur or better focus everything before and after the main subject. The rule is that the more the diaphragm is closed, the larger the sharp area is and, naturally, vice versa.
So, for example, if we want to shoot a field of daisies in its entirety, we will keep the diaphragm closed to have as many flowers properly in focus as possible.
And if instead we want to photograph a flower isolating it from the rest of the plants, we will open the diaphragm fully. For more or less pronounced effects we will use intermediate values.
The lowest number of the diaphragm indicates its maximum aperture and also gives an idea of how bright a lens is. Remember Barry Lyndon?
To film candlelit scenes, Stanley Kubrick’s director asked Zeiss to build special lenses so bright that they could shoot images almost in darkness: the maximum aperture of the optics was f:0.7! today it starts at 5.6 and up…
(photo:Reduced depth of field achieved with a very open diaphragm)
Another thing to know about the diaphragm is that old photojournalists and paparazzi had no autofocus system and could not afford to take blurry photos, especially at night and outside nightclubs.
To avoid the risk of out of focus, they used, as Ansel Adams taught, the “hyperfocal distance.”
If you happen to have an old manual lens in your hands, looking at the barrel you will see marked notches, often colored, numbered in the same way as the diaphragm apertures.
By positioning the “infinity” symbol, engraved on the distance scale, on the notch corresponding to the diaphragm used at that moment, the focus field will extend towards us up to the distance read on the other notch of the same color.
Carefully observing the hyperfocal distance scale engraved on various lenses, we immediately realize that the more closed the diaphragms are, the greater the depth of field will be, and that this breadth will also depend on the focal length of the lens used: with wide angles, in fact, it will be greater and with telephoto lenses. (photo: A scene from the film Barry Lyndon by Stanley Kubrick filmed by candlelight).
Next time we’ll say something more about diaphragms and talk about shutter speed…)
Complete photography course
- Photography course: which camera to choose?
- Photography course. The beginning: useful advice
- Photography course: sensitivity
- Photography course: blurred or shaky?
- Photography course: the circle of confusion
- Photography course: the diaphragms
- Photography course: the battery
- Photography course: how to hold the camera
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