SIGMA APO 1.4X EX DG TELECONVERTER FOR PENTAX

https://www.sigma-global.com/en/news/2008/10/10/10240/

It is possible to use AF
APO 70-200mm F2.8 EX DG, APO 70-200mm F2.8 EX
APO 100-300mm F4 EX DG, APO 100-300mm F4 EX IF
APO 300mm F2.8 EX DG, APO 300mm F2.8 EX

It is only possible to use MF
APO 50-500mm F4-6.3 EX DG, APO 50-500mm F4-6.3 EX RF
APO MACRO 180mm F3.5 EX DG, APO MACRO 180mm F3.5 EX IF
APO TELE MACRO 300mm F4, APO TELE MACRO 400mm F5.6
APO 500mm F4.5 EX DG, APO 500mm F4.5 EX
APO 800mm F5.6 EX DG, APO 800mm F5.6 EX