Hi all

Ive not long brought a Sigma 70- 200mm F2.8 Lens
on a website ive seen for sale a Sigma AF 2X EX DG Extender Canon EOS
am i right in thinking that this would give my lens a focal length of 400mm then have to x it by 1.6x as im on a 500D APS-C sensor
giving me a FOVCF of 640mm is this right in the way ive worked it out

hope some one on the forum knows about Extenders

cheers Russ