Teleconverter / Extender

[jrbrown1991]

Do these affect the sharpness range / bokeh also, or do they only affect light gathering?

Thanks :D

[TheWengler]

They can cause a drop in image quality. They can also cause you to lose autofocus if you don't use them with a fast lens.

[jrbrown1991]

O.K... but, what I mean is... will there be 'less' bokeh because it's equal to 2-fstops less?
i.e. f/4 is less sharp than f/8... (is that 2 stops?)