I have checked the Sony web site to seek an answer, it appears there may be only 4 lenses these items are suitable for use with. I'm puzzled, because I used the 20TC last week with an old Minolta APO 300mm F2.8 I managed to source. Having seen the web site, I wondered if the TC would be OK to mount with the Zeiss 135 F18 I have with my A99. Just asking for some confirmation from the experts out there.