Tele/Wide Converters , Adapters, Extension rings/tubes, reversing rings
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Tele-Converters
The tele-converter is a device that mounts between the camera body and lens and increases the effective focal length of the lens.
Reversing Rings
A lens-reversing ring is a metal ring with a camera-body mount on one side and a threaded ring on the other side into which the front of the camera lens screws. The lens is used reversed.
Why use the lens reversed? Because standard lenses are optimized for normal distances. Reversing the lens produces better results for close-up pictures.
Extension rings/tubes
An extension ring is a ring between a camera body and a lens. It increases the distance of the lens to the film plane and thus it allows a closer focusing.
Wide-converter must be attaced to the front of the lens and it is not commonly used with a system cameras,An exampe of a wide-converter which in this case is more or less a junk. Perhaps a decent peephole. (right)
The principal idea of the so called system camera is that it could be adapted to numerous jobs with a range of interchangeable components and specialized accessories. Today, even the most moderately advanced 35-mm system camera can take interchangeable lenses, data backs, close-up and photo micrographic attachments, winders, etc.
Perhaps the most popular accessories for the amateur photographers are various converters, adapters and extension tubes. The main advantage of a converter compared to extension ring or tube is that the minimum focusing distance remains the same when a converter is used and unlike with an extension tube you can stil focus to the infinity. Thus, if you have a 100mm lens that focuses down to one meter, it becomes a 200mm lens that focuses down to same distance when attached to a 2X tele - converter. Because of this, you can get better close-up images by using it. Tele-converter is more expensive than tube because it has optics but it is also more versatile.The main drawback of tele-converters and extension tubes is that they cause a loss of lens speed and they also have more or less negative affect to the overall lens performance. Thus, the development of more and more better and effective zoom lenses might abate the demand of this kind of equipment. |
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Tamron 2x Tele-converter for Minolta MD-mount. (right)
Most major-brand tele-converters produce good results. There is a slight loss of image quality, but not a lot. Some manufacturers offer matched tele-converters, made specifically for use with a particular lens (or a specific focal-length range). These can produce even better photographic results than general-purpose converters.
Nikon TC-14A, 1,4x Tele-converter (left) |
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Vivitar 2x Macro Focusing Teleconverter (left)
A splendid idea which is also working, being a teleconverter it is a extension tube too. With a matched lens it produces acceptable results.
Minolta P-Adapter (right)
This adapter converts Minolta MD-mount suitable for Pentax thread lenses.
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Gold Line Wide-Converter  |
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©2004 Reijo Lauro
