Hi Ram,
I have complied the following from WEB:-
Teleconverters, also known as multipliers and doublers are attached to lenses to increase their focal length. They are available in 1.4X and 2X versions. There is a one stop loss of light when a 1.4X converter is used and two stops with a 2X. A 300mm f- 2.8 lens for example, becomes a 420mm f-4 with a 1.4X converter and a 600mm f-5.6 with a 2X. There is some loss of sharpness when you attach a converter to your lenses specially with a 2X converter and with open apertures. Some converters are designed to work with specific lenses and cannot be used with other lenses. if you are buing one Check the brand you wish to purchase and make sure they will work with lenses you plan to use.
Teleconverters can also be used in close-up photography to increase magnifications ( my picture for example)
When choosing a converter check its elements. The higher element converters produce better quality pictures but are more expensive. Independent lens manufacturers make converters for most popular brand lenses and they can be fitted to any lens. However, quality you obtain depends greatly on the lens/converter combination. Zooms and mirror lenses don't work too well with converters attached. Telephoto lenses are used with converter for greater reach. If you don't have a converter you should look in to buying one as they are great tools and are a lot better in quality than the ones from only a few years ago. Canon, Minolta, and Nikon make 1.4X and 2X converters but they only work with certain longer lenses only. Sigma, Tamron, Kenko (Part of THK co. , Tokina, Hoya, Kenko) also make good quality converters at much lower prices and they can be fitted to almost all lenses.
The 2x that i use is Tamaron, for more details vist the following link
http://www.tamron.com/lenses/prod/proteles.asp
Regards
Goutham R |
India
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goutham_ramesh
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