View Full Version : Lens Compatibilities

13-03-2010, 11:17pm
Hello fellow Pentaxians
I recently got a Pentax AF TC 1.7 and have tried with MF lens to convert them to AF with success(This is its capability)what Im after is a list of lenses in AF standard to use ie sigma 70-200 f/2,8(although I have tried it with a sigma 100-300 f/4 it didnt work as in the viewfinder it showed f/2.8).The list below is a standard list from Hoya


14-03-2010, 8:48pm
With the 1.7 conversion factor and the 1.5 cropping factor, a standard 50mm lens would become 127mm equivalent! Amazing.

17-03-2010, 7:34pm
With the TC it only becomes 50X1.7 its a 85mm FL.Just what to know is it best to stick with primes as this would be the logical outcome or has some one else used this TC with fast zoom lenses ie f/4 or wider


JM Tran
17-03-2010, 7:51pm
I have used this before to turn a manual Tokina 80-200 f2.8 into auto focusing, it was ok at best, due to the push-pull zoom mechanism sometimes I find the AF would hunt a bit as it was so loose (zoom barrel)

17-04-2010, 5:29pm
I've only used mine with prime lenses, where it's perfectly happy.