Originally posted by justtakingpics Does the teleconverter degrade the image significantly?
I've been wondering that, too, so I did a little test. I'll start with the disclaimers:
This was a quick, completely unscientific endeavor. There's variation in the exposures, but I was careful to get the best focus possible on all images. The lenses and TCs used were (mostly) a motley bunch. Not exactly the best and the brightest. That said...
camera: K10D, jpegs, no PP except for WB on the Tokina
lenses: Tokina SD 400 f/5.6, Vivitar 200 f/3.5, Prinz 135 f/2.8
teleconverters: Kiron MC7 2x (7 element), Focal 2x (4 element?), Vivitar 3x (?? element)
All shots from the same spot, on a tripod, 3 second remote control timer, all @ f/8.
The Tokina 400 was the baseline. I made a moderate crop of that picture and cropped the rest to match the FOV of the (cropped) Tokina shot. I shot the Vivitar 200 alone and then with each 2x TC. I shot the Prinz 135 alone and then with the 3x TC. For reference, the first picture is the original, uncropped Tokina 400.