Is it possible to use a 2x TC200 or TC201 with this lens, I know it will affect the aperture by 2 stops but will it introduce vignetting?
The 500C lens has quite some vignetting by itself, possibly it will benefit from the addition of a teleconverter: the image corners with light falloff will be cropped out of the final image. You can always give it a try... but remember to remove the 39 mm filter at the back of the lens before attaching it to the teleconverter.
Ciao from Massimo
