|Fully-extended macro vs. 2X teleconverter|
I do not think that Pentax have ever made such very useful device for both macro and tele shooting and for both Pentax KA and Ricoh P mounts. Among the 7 pins on its mounts, 6 in one group are for KA mount and the separate one (also safe to use on Pentax AF mount) is for Ricoh P mount. A smart design! Thanks to the old Vivitar (not today's Vivitar that owns the brand, but didn't manufacture this old and wonderful adapter).
The 7 pins on both front and rear mounts are linked with 7 springs inside. However, they are easy to fall off from the anchors close to the rear mount. This happened in my copy. By opening the mount, I re-installed them, following the instructions at pentaxforums.com. I also posted its user's manual/instructions in one of my previous blog pages.
Its internal/front barrel extends, but does not turn. Its rear glass element does not move.
Its macro ratios for a 50mm lens are marked separately for 2x tele-converter (1:1.5 to 1:20) and extended internal barrel (1:1 to 1:3).
It is bigger and heavier than other regular 2X teleconverters.
The major concern of its users is the quality of its images. Used as a 2X TC, it was mounted between my Pentax K-x body and SMC Pentax-A Macro 1:2.8 50mm lens, and compared with Kalimar and Sears 2X KA TCs. The following settings were used: the minimum distance on lens, f2.8, 1/180 sec, ASA 400, on-camera flash, room light, and hand holding. I think, the images with Vivitar 2X macro focusing TC are the best.
Images with Vivitar 2X MFTC:
Images with Kalimar 2X TC:
Vivitar also produced a PK version (without the pin contacts), but the P/K-A R-P/K version is easier to use on Pentax DSLR and more expensive in the second-hand market.
As I noticed later, there is a various color version with macro ratios marked in green, not blue and white as in my images above.