Originally posted by Michael Shea For what it's worth, I've purchased numerous lenses manufactured by Panasonic, Olympus, Tamron, Sigma, Fuji and Pentax within the past five years. The bare minimum expectation I have from a digital lens is that it can auto-focus correctly outdoors in decent natural light. Of those manufacturers mentioned, the only one producing a lens that failed to meet my personal standards has been Pentax. Not a single copy by any of the other manufacturers has disappointed in terms of focusing. Pentax has done so on no less than three occasions and I'd never buy from them again. It has nothing to do with back focus or front focus, this is the whole frame being out of focus at medium apertures in broad daylight. And yes, my green focus confirmation light came on every time.
So please don't patronise people who report these issues. Most of us know perfectly well how to operate a camera and realise when something is seriously wrong. I may have been extremely unlucky, but I've given Pentax a fair chance and they've let me down too often to deserve the benefit of the doubt, or for that matter my money, any longer.
Test your lenses and return them immediately if they don't perform as expected. Is pointing out I've seen posts on other forums by people who have the same issues you do with other companies, is that patronizing? In you experience, Pentax is awful, in other's experience, Pentax is wonderful, and there's a lot of in between. That's reality. But I think it goes without saying, if everyone had the experience you did, Pentax would have no customers.
You have my sympathy for your bad Pentax luck, it must really suck. But one of our forum members just talked Ricoh into sending him a brand new lens. If you read through the forum lens reports, you'll find very few people originally get bad copies of Pentax lenses.
On the other hand, the Tamron 70-200 described by MikeFS, has probably the worst record o any lens on the forum. 10% of them are defective right out of the box. But if you get a good copy, people seem to really like the lens. One person even got 2 bad copies.
I've received one copy of a lens that was bad right out of the box, and that was the Sigma 120-400. Then I got a working copy after paying an extra $120 for OS, after they shipped me the wrong lens and then charged me the extra, and had to send it back because it just wasn't a good lens. I'm one of those crazy people who expects to get good optics for $1100.
I could have tied my knickers in a knot and said "I'm never buying from Sigma again", but I've since bought a Sigma 8-16 and a Sigma 70 macro, which are just amazing lenses, lenses you'd have to pry out of my cold dead hands.
So it leaves you with a choice, are you going to get the lens and return it right way if it doesn't test out, and get a really great lens? If I've learned anything it's that anyone can sell you a bad lens. You want to say it's just Pentax and that's your experience, but honestly, when I read the experiences of thousands of viewers, that doesn't hold up. Sorry it had to be you, you have my sympathy.
If you talk to Canada Post, you have to package stuff so it can survive a 5 foot drop. We've had Canada post drive a forklift through a print we shipped to a customer. I'm willing to bet in a lot of cases, lenses that tested out perfectly in the factories are getting knocked out of alignment in shipping. So, blame the lens companies if you want... but they only control what happens to the lenses until it leaves the doors of their factories. My guess is a lot can happen between them and you.
But hey, that's probably just me being patronizing, I should shut up now.