Hello everyone!
I'm opening this thread hoping to find some answers to my questions, but also maybe it'll be useful for other K-7 owners.
I owned a Tamron 17-50mm and I found that on my K-7 body all images are front focused using the AF (I described the problem
here).
After 30 days of waiting for a solution from the service, I went to the store and they decided to replace the lens with another copy. They tested the new one on my camera, but we discovered the exact same front focus values. They repeated the tests with all new copies they had in stock (6 pieces), but with the same result. I asked them to test with another Tamron lens type, the 28-75mm F/2.8, but unfortunately the big front focus was still present on all (3 pieces). It was so big that we didn't managed to compensate it in AF Adjustment menu.
Sad moment for me because I love the Tamron 17-50mm IQ & sharpness and I was also thinking that my camera is the source of the problem. Maybe it is...
Anyway, they gave my money back so I went to the local Pentax distributor and tried a DA* 16-50mm. And guess what? With this this lens my K-7 is focusing perfectly even in low light/poor contrast situations.
So now I own a brand new DA* 16-50mm (and I hope without any already reported issues on this forum), but being just a hobbyist & novice photographer I have now more unanswered questions:
Are there any K-7 owners that discovered the same focus issues with Tamron 17-50mm and/or 28-75mm lenses, or I am the only one on the planet?
I don't understand why all my Pentax (DA 18-55 WR, DA 50-200 WR, DA* 16-50) and Tamron (90mm F/2.8) lenses is focusing perfectly on my K-7 body, but the Tamron 17-50mm & 28-75mm don't. Can anyone give me a reasonable explanation for this?
Is it possible that K-7 has a compatibility problem with Tamron chipsets in those lenses?
To mention that I've installed the latest firmware available for K-7 a few days before I bought the Tamron lens, so I cannot tell if the AF issue is somehow related with this firmware release.
Thank you in advance.
PS - Please excuse me for my pretty bad English, it's not my native language and I don't use it very often.