he only checks in a couple times a day -- I'll attempt an explanation:
A TC is a teleconverter.
It's basically a secondary lens that fits between the camera and the primary lens in use.
They come in two sizes: 1.4x and 2x.
The 1.4x extends the focal length by that much (a 300mm lens becomes a 420mm) and "slows" the lens by one f-stop (2.8 to 4).
A 2x teleconverter extends the focal length by 2x (300mm to 600mm) and "slows" the lens by 2 f-stops (2.8 to 5.6).
They work best with fixed focal length lenses but some work well with zooms too. Most good ones are a few hundred bucks (however you really get two lenses (a 300 & a 600, say) for much less than the cost of two primary lenses).
make sense ??
