Few share my view but I think the real difference between the LIMITED and the rest of Pentax primes are indeed - metal. I have come across some defective MIJ Limited lenses to make me believe they did not receive tighter QC. Optical formula is something we cannot compare because Pentax did not make them available in non-Limited form. But based on other reviews and my own experience, FA31 is the only "special" one that truly stands out. The rest are just regular optics in M series like body with AF for the yummy price tags. Anyone in business know it is not what you actually sell, but how people perceive your products that sell. The Limited idea was a lucky accident that save Pentax in recent history. And my own speculation is that in 1997, when the FA43 was released, Pentax was uncertain on what to expect and planned to make it a one-off product and so LIMITED was called. But the success took everyone by surprise and the FA77 was released in 1999/11 (I happened to be in Japan at the time and saw it 1st hand in magazine and bought one). Some years later it was tested against the EF85/1.8, and to my surprise, it was beaten by the EF in every areas from sharpness to CA control. These weakness are even more obvious on digital. The FA43 is not that great on FF either because of barrel distortion and edge sharpness outside the APS-C format. Wide open it is just soft and donut bokeh is obvious. The FA31 could have been perfect but it was cursed by the fixed hood, and beneath the familiar metal skin, its build quality is nothing like the rest of the Limited lenses due to floating design (very very rare in Pentax history, also why its focus ring is so loose). The FA31 is also one of the very few Pentax lenses with molded glass AL. If the Pentax Japan website didn't mention they were glass AL, they would be molded resin AL which are cheaper and lower in clarity (FA35/2 for example). The DA Limited are nicely build like FA43/77, but some of them had loose aperture blades or other issues due to QC. But when properly assembled, they should be trouble free for the rest of their useful life.
Last edited by wlachan; 04-10-2010 at 02:16 AM.