Thanks for your comments, I can now make an informed decision on the 1.4

Hi, can anybody advise what lenses are fully compatible with the 1.4 converter, I have the following lenses:
SMC PENTAX-DA FISH EYE 3.5 - 4.5, 10 - 17MM ED (IF)
SMC PENTAX-DA 3.5 - 5.6, 18 - 135 MM ED AL (IF) DC WR
SMC PENTAX -DA 4.5 - 5.8 55 - 300 MM, ED

Will the auto focus on the 1.4 x converter work on these lenses

thanks, Alan