09-23-2014 12:38 PM
Greetings. While we no longer produce a 2x converter, you may likely have to look in the used marketplace for this product. (We are not aware of current availability, however).
PENTAX produced two 2x converters, as follows:
30944 SMC-A Rear Converter 2.0x S - 6 groups, 7 elements. Loses 2 stops.
30945 SMC-A Rear Converter 2.0x L - 5 groups, 6 elements. Loses 2 stops.
For some longer lenses (300mm - 1200mm)
These converters work with all Program exposure modes on Pentax FA, F, and A series lenses, but the lenses must be focused manually.
Good Luck and Thanks!