Originally posted by jawsy That's because there's nothing to find. Despite what some would have you believe, a lens is a mechanical component built to a pre-defined specification. Unless a batch or series was released outside the build spec, they are all going to produce the same image. 'MIJ' is nothing more than sentimentality that unfortunately results in people paying a premium for an anodised stencil.
It is mostly true but not 100% true. The first MIJ limited where using apparently different coating with lead that are now forbidden in some countries and they changed it so they could continue to sell it. There where also more problem reported with earlier AIV batches than with MIJ making for unhappy customers.
If you buy new, there nothing wrong with the AIV and if you lense is within specs, there likely no reason to want an MIJ except if you can find a very low serial where you might see a difference in rendering due to coating.
Is it better or worse? That might be even personnal. It is also possible Pentax release an updated version of their FA ltd in DFA form so without purple frigging issue, rounded blades, quick shift and latest coatings. Maybe even DC motors and no apparture ring. That would make sense at some point as they now have an offical FF body to come by end of year.
Theses new lense might turn out to be even better than the old one... Or to loose some of feel the old FA ltd had. Depending on all of this, the value and interrest for theses old MIJ lenses might change entirely.