Thanks! I agree, both are very close. I'm just glad my 250SA appears to be a well-centered and pretty accurate copy.. not like those are easy to return / exchange for a different one!Thanks for the excellent test, Brandon! Both look quite good to me. The Mutar looks like it offers a bit more contrast to my eye but they are both doing very well for a 2x telephoto extender and I couldn't see any significant acuity difference between the two teleconverters in your shots. Starting with a world-class lens helps!