ssymeono wrote:
... extenders work very well with primes. We must admit that the manufacturers know something when they produce these lenses. Nikon used to ship its 300mm, 2.8, with 1.4 extender in the box, meaning that they really believe in the combination.
Cannot provide examples because i use nikon but have heard from several sources that at times canon has actually employed telextender lens elements as a built in part of certain telephoto lenses with good performance.