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Lenses for Unusual Effects - 1 - Special Techniques .. How to Take the Most Beautiful Pictures .. Photography Book

Special Techniques
Lenses for Unusual Effects

A photographer worthy of this name needs a photographic device with interchangeable lenses. Knowing that there are a large number of lenses, most photographers usually only use three of them unless they specialize in a special field in which special lenses are necessary. Lenses vary according to the size and nature of the photographic device: A wide-angle lens estimated for a 24 x 36 reflex device does not fit a 6 x 6 cm device. For some cm devices, manufacturers sometimes suggest four or five wide-angle lenses, each with a different focal point.

The main advantage of interchangeable lenses is that they allow changing the image magnification or bringing a very distant subject closer or capturing a very large view in one image. Wide-angle lenses magnify the perspective, especially towards the edges of the image and emphasize the first plane at the expense of the background plane. These lenses are often used in still lifes, portraits with legs, or reportage, especially if there is no way to step back. They represent the subject very directly, putting the viewer in the foreground.

The perspective given by a normal lens is convincing, the image is slightly distorted or not: the first plane, the intermediate plane and the back plane are all in their natural proportions. The maximum aperture of a conventional lens is usually 1.8/F or 2/F for a small machine and the field angle is between 50° and 45°. This means that in a 24 x 36 reflex camera the image has a magnification exactly similar to that seen with the naked eye. A long-focal (intermediate) lens - 80 to 200 mm for a 24 x 36 mm - gives a perspective almost identical to that of our eyes, much in the dimensions of the back plane relative to the main subject, and it is an enlargement that allows a short-distance subject to be photographed in a large view. A very long-focal lens magnifies distant objects but simplifies the perspective considerably. Long focal length (intermediate) lenses are very light, can be used with the hand raised, and require a shorter f-stop than shorter focal lengths. In general, the shortest f-stop that can be applied with a long focal length lens is related to this focal distance: for example, a 135mm lens should not be used handheld at a f-stop slower than 1/125 sec, a 500mm lens requires 1/500 sec, etc. This is to prevent movement.

The zoom - variable focal length lens -
is usually calibrated whatever focal length is required and whatever the magnification. The image may have a lower resolution than if it had been produced by a fixed focal length lens. However, the zoom is still very useful for certain sports reportage scenes where absolute clarity is not a primary requirement.

- Long focal length lens
A traditional Yorkshire scene. Mine waste dump near the coal mines To show the enormous scale of the waste pyramid and to capture the industrial atmosphere of autumn fog, I took this picture from 3600 metres away with a long focal length lens. This also allowed me to give the setting sun an exaggerated diameter. The focal length I used simplifies the perspective and gives a very weak depth of field.
Pentax 1000mm 1/500 sec 5.6 Kodak Tri X

- Changing focal length
These three pictures (first on page 179) represent the same scene taken from left to right - with a wide angle lens, a normal lens and a 90mm long focal length lens. The shorter the focal length, the greater the distance of the field, regardless of the aperture. The area recorded on the film also increases as we move from a long focal length to a shorter one. The magnification varies in the opposite direction. The long focal length gives a stronger magnification of the subject. The back angle it covers is narrower than that of the normal focal length and the surfaces appear to come closer together: they are compressed.