The User's Review: Kalimar 2X Tele Converter KAR vs. Sears Auto 2X Tele Converter 4E/MC KR 271.8100

I happened to have these two adapters in hands. At my first look, I thought that they were re-branded from the same manufacturer since they had the same hosting rings, 7 contact pins and caps. However, when I took pictures of them, I found that the rear element on Kalimar adapter was located more inward when looked from the rear end. Therefore, they are different optically.

I also took some test shoots with them, using the same settings on my Pentax K-x and SMC Pentax-A Macro 1:2.8 50mm lens. In my eyes, the images through the Kalimar adapter (the top two) are better in terms of resolution. What do you think?

Both adapters are safe to mount on Pentax AF bodies although the mark "KAR" (for Pentax KA and Ricoh P) on the Kalimar is more proper. 

I have a separate post for the Sears Auto 2X Tele Converter.