Many times in this Pentax sub-forum and elsewhere, the debate on whether a lens that was made in Japan was in some way "superior" as compared to the supposed inferior quality and manufacturing standard of a made in Vietnam lens frequently rears its head. Most recently here. This issue in particular crops up with reference to the expensive and top of the line FA Limited and FA series lenses. My take is I am not particular if it says Made in Japan or Made in Vietnam (where it is made won't show up in your pictures).
Anyway Ned Bunnell, the President of Pentax USA has come forward to try to clear the air on the matter on his blog. http://nedbunnell.blogspot.com/2010/02/country-of-origin-debate-over-lenses.html
His conclusion:
I would not be overly concerned with the country of origin for any high-quality lens that you consider buying today. Based on my tests, I can't see or feel any difference between my FA31mm samples.
Anyway Ned Bunnell, the President of Pentax USA has come forward to try to clear the air on the matter on his blog. http://nedbunnell.blogspot.com/2010/02/country-of-origin-debate-over-lenses.html
His conclusion:
I would not be overly concerned with the country of origin for any high-quality lens that you consider buying today. Based on my tests, I can't see or feel any difference between my FA31mm samples.