Accessories – The Teleconverters
The teleconverter is an optical system (with build quality comparable to that of the objectives) can enlarge the image from the lens. This is done by diverging light rays coming from the lens in order to go to hit a larger area of ??the sensor, or rather, by making a real crop optical image compared to what we would see directly with l ‘ target . Obviously, being the magnified image and, more scattered rays on the sensor (and some out from the sensor), the brightness suffers drastically with a loss of 1 stop in the case of a multiplier 1.4X and two stops in case of a multiplier of 2X.
Just to give an example, if we use a lens with a focal length of 135mm and f 2.8, by applying a multiplier 2X we would have a focal length equivalent of 270mm (and resulting angle of view, equivalent or better crop) and brightness of f 5.6. Even if we apply a 3x multiplier http://www.akusewa.com/sewa-led-screen-jakarta, we would be to have the equivalent of a 405mm f 8. A bit ‘too dark for the final price of the instrument teleconverters can be quite expensive, considering that the two Canon of photographs ranging between 400 and € 600. Obviously I exist first-level brands but different from the two super brands that sell these items at prices that reach around 200 €, more than acceptable
The teleconverter therefore has the merit of increasing the focal length but to keep its minimum focusing distance. Even their compactness and lightness are absolutely interesting because they allow to create economic webs in terms of weight and size. The multipliers of focal are also equipped with electronic Normally all electronic commands are given to the body, so you do not lose the automatism.
If they have not given a lens hood with the lens, so remember to buy one consistent with the lens. Normally, a normal lens hood (so no special symbols) is used on targets ranging between 35 and 70 mm (or 65 and 120 for the objectives half frame) and a lens hood Wide Angle (WA) is mounted on very short focal lengths (is very more flared and short). On telephoto lenses (more then 120 or 70mm) you can use a longer lens hood (normally recognized by TELE acronyms), while on the very wide zoom (18-105 as the basis, for example) you ALWAYS use the lens hood to the shorter focal length, to prevent vignetting effect.