Teleconvertor Test
Bob Atkins has published a comprehensive test of teleconvertors, which are are optical devices which when attached to the rear of a lens increase the effective focal length. Are they a relatively cheap and effective way of adding focal length? Bob has the answer.
“So how well do they work. Well here are a series of test images that might give you some idea. I used a Tamron 1.4x TC with three different lenses/. First a Canon EF75-300/4-5.6IS, representative of a consumer grade telephoto zoom, second a Canon EF28-135IS, representative of a reasonably good consumer grade mid-range zoom, third a Canon EF300/4L, representative of an excellent “L” series prime lens and fourth, a Canon EF50/1.8 representative of an inexpensive consumer grade prime lens.”