Originally posted by emr Thanks for the input, bdery! Since you're in the optical business, may I ask how did you end up getting the lenses you have in your signature (Sigma 17-70 | DA 18-55 WR | FA 100-300 | FA 50 macro | F 50 mm f1,7 | M 150 mm)? I mean did you get them based on reviews or non-formal testing or did you perform some more rigorous optical testing?
Many of these lenses were bought used, on auctions sites, here, or in classified ads.
When I first got into the Pentax system, I decided right away that I didn't want the kit lens, but bought the Sigma instead, as a good all-around package (if the DA 17-70 had been weather sealed, I would have bought it instead). I already had a few manual primes. I wanted a fast night photography lens in my kit, a macro, a tele, and I just recently bought a WR kit for snowshoeing and difficult situations (bought it here from the marketplace).
Regarding the Sigma, I chose it because of reviews and user reports, and based on its features.
I bought the F 50 f1,7 knowing that every fast 50 is good. I found the 50 as part of a kit sold online and bought it. I don't regret it, it's perfect for what I need. Any f1,4 or f1,7 50 will be great though (I have owned the A 50 f1,4 before, and sold it because I wanted AF).
I found an amazing deal for the 50 macro, and I knew it was one of the sharpest lens out there, which is what I wanted. Any macro lens is probably good.
The M 150 was an almost-freebie I bought and even though I don't use it much, it's useful in some specific situations.
The only lens I'm not 100% satistied with is the FA 100-300. It's a good lens, but it lacks the special something of most of the others. It doesn't have real flaws, but results are always good, not great. Maybe I'm part of the problem
I got it to replace a 70-210 f3,5 lens which was bette optically, but was also much, much larger and heavier, and MF (meaning the wife would not use it). this is the lens I will at some point replace.
I do not do extensive testing on my lenses, I do check their general performances when I get them, to know what to expect at different apertures and focal lengths. But my "tests" are based on real life photos. For instance on my (5 minutes) test the 100-300 proved sharp and mostly aberrations-free, but it still lacks something ...
Even though I understand lens design, it would be impossible for me to evaluate lenses based on their designs, there are way too many choices and possibilities and design parameters implicated. The best test is just to mount a lens and start shooting. Being an "optics expert" so to speak lets me understand a bunch of things but there is more than that to photography.
I hope it answers your question. Feel free to ask for clarifications.
Quote: one thing that you must consider that they don't share the same personnel in those plants. the question is how QC is being implemented. products that seem to pass the standard of one manufacturing plant may not be the same as that of the others. and this is not an assumption.
Pentaxor, of course you are right. The way QC is implemented is the critical point. For instance, in our company, the manufacturing process is put in place at our main plant, with the participation of the R&D team. Then, when all the tests are agreed upon, the tolerances defined, we can transfer to China, where the products have to pass the same tests. It's the job of the R&D to make sure the right things are tested.