We have looked at the ways we can regulate our cameras to get the right exposure, but until now we haven’t discussed exposure itself. Correct exposure is simply setting the camera so that the subject is rendered with an appropriate range of tones in the image.
If the camera allows too much light in, or over-exposes, then the image will be too light, appear washed out, and particularly in digital, highlights will ‘blow out’, that is, be rendered as solid, featureless white. If there is not enough light, or under-exposure, the image will be too dark and the shadows will appear jet black with no detail.
All modern digital and film SLRs have very sophisticated systems of measuring the light coming from the subject and setting the camera automatically and this is exactly what a lot of photographers do. I do it myself, if there are no lighting complications or other factors to worry about. However, as soon as you begin to play with aperture and shutter speed, it really helps to know what you are actually doing. Continue reading “Photo Technique 5: Brightness and Exposure”
Four key factors in photography are linked: aperture, shutter speed, film or sensor sensitivity and subject brightness. These are linked in such a way that if any one is changed, then one or more of the others must also be changed to compensate. The first two, aperture and shutter speed, are easily controlled on camera, and now we will look at the third factor, which is also under the photographer’s control: film or sensor sensitivity.
In pre-digital days this was always referred to as ‘film speed’ and this is convenient; we continue to use it to describe digital sensor sensitivity — sensor speed. A number of indices or scales were established to measure film speed, but the one that became the most widely used was the American Standards Association, or ASA, scale, which was eventually adopted by the International Standards Organisation or ISO. This is an arithmetical scale, so that a doubling of the ISO value indicates a doubling of sensitivity or speed, and a halving the opposite. (This is as opposed to the more complex DIN scale which was logarithmic.) Because the ISO values are arranged in this way, they conform exactly to the conventions we have already met for aperture and shutter speeds, where each stop or step is a doubling or halving of the one before. So it is easy to apply the same logic to film/sensor speed.
Shutter speed is one of four interdependent parameters that are central to photography. These are : Aperture, Shutter Speed, subject brightness, and film or sensor sensitivity. IF any ONE of these is changed then AT LEAST one other must also change to maintain the same exposure. The most common example of this is that if aperture is altered, then shutter speed must also be altered, reciprocally. So if aperture admits less light, then shutter speed must admit more.
We have already discussed aperture, and seen how the f-stops marked on the aperture ring are calculated and what they are. To recap, the focal length divided by the aperture gives the f-stop, so a 50mm lens with a 25mm aperture is f2, and the they progress f2, f2.8, f4, f5.6, f8 and so on. Each of these allows half as much light to pass as the f-stop before, counting from low to high.
If you look at the lens barrel you will probably see a ring which controls the aperture diaphragm. This will be numbered in f-stops, which on modern cameras will run f1.4,2, 2.8, 4, 5.6, 8, 11, 16, 22, (32, 45, 64). I put the last three in brackets because you’re pretty unlikely to have them but you might see them on view cameras. Note that the numbers double on every second step—2,4,8 etc and 2.8, 5.6, 11 etc. The f-stops are determined by dividing the effective aperture into the focal length, so a 50mm lens with an aperture of 25mm is f2, and with 12.5mm is f4. Each f-stop, going from low number to high, admits half as much light as the one before, so f2.8 is half of f2 etc. It’s easy to work out why if you’re mathematically inclined, but if not, just remember it.
I grew up in a world where photography, especially monochrome photography, was synonymous with ‘truth’. That was never strictly accurate, of course, and as a photographer I knew the extent to which the truth can be manipulated. Nevertheless, as evidenced by the incredible work we saw every day in the newspapers of the 60s, which I consumed with passion while still at school, a photograph was regarded as an equivalent to reality; it was not just a representation of truth, but an affirmation of it.
“Look,’ it said, ‘This is a true thing; I stand witness to that.’ Even today, when PhotoShop has put tricks of the trade that I spent years learning at the click of an amateur’s mouse, photographs brook no argument. The leaves really were that green, the sunset that orange, the woman so perfect. Yet perfect beauty was never in the sorcery of the darkroom or the airbrush artist’s hand, nor is it in the magic of digital manipulation; real beauty is actually real. It needs no PhotoShopping or dastardly manipulation, only to be seen and known, and recorded.
The other part of my life, however, is very different from the ascetic artist whose delight is in the expression of pure form or idea. As a musician, I am by definition an entertainer. And my professional photographic career has been mainly in Photojournalism. Indeed, long before I immersed myself in Weston and Brandt I was mainlining Cartier-Bresson and Don McCullin. Continue reading “The Naked Truth”
Focus and depth of field are related, and the advancing photographer should understand the relationship between them.
If you are used to using a digital compact, then focus may be something you take for granted. Things just are in focus. But if you are thinking of buying a DSLR or a film camera, then focus becomes much more important. In fact it is one of the primary creative tools the photographer has.
Lenses resolve the light emitted from objects in the world into an image that we can use. Sometimes, as in a telescope, this is for direct observation, and the focus is inside the eye; in photography, resolution is always on a plane behind the lens.
On the 25th of February 2017, we went to Malolos, the capital of Bulacan, to see a ladyboy parade; but it never appeared. Ladyboy levels of disorganisation are, of course, legendary, in addition to which, they were probably working on Filipino time, which makes ‘manana’ sound urgent. Still, a couple of nice cold Red Horses and some good pictures.
Street photography, long established as an art and a specialist form of photojournalism, requires very similar techniques to those needed to photograph field sports, notably football (soccer, not that American nonsense). You need sharp reactions, complete confidence in technique and total reliance on reflex. As soon as you see an image, it’s gone, so you just have to go with it.
Markets everywhere are wonderful for this sort of thing. They’re very colourful and people are concentrating on selling, not watching the photographer. I was using a DSLR for most of these, with no issues. As usual with digital, you have to watch the exposure. I find using the old tranny technique of underexposing by 2/3 of a stop is useful in holding highlight detail.
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