Originally posted by angerdan Model line of an filter brand has more influence about the quality than the brand.
I'd already wrote that:
Basics don't have to be tried by everyone. They're already proven and accepted.
40 years ago there hasn't been AF SLR cameras. Technical and optical engineers who are involved in the manual writing process have experience and professional knowledge.
autofocus - Why do AF systems have polarizing elements? - Photography Stack Exchange
Not experiencing issues by siimply trying something don't change the basics. It even doesn't show them.
And i don't have any reason to buy an linear PL and trying to proove you right and the basics wrong.
All about Polarizers - Linear and Circular
It's what you like to hear, but the information isn't correct.
Things change. Don't get stuck living in the past and repeating old information that no longer applies.
Lots of people repeat old wives-tales simply because they never thought to question what they've been told.
Sad but true.
"Not experiencing issues by siimply trying something don't change the basics."
If first hand experience didn't "change the basics" the issue would still be present and this conversation would not be happening. Scientific studies are proven "wrong" all the time as more information becomes available, or as current technology changes.
The Wiki link is interesting and full of non-attributed information and lacking references. It is also full of questions without answers.
The last bit of text is also of most interest;
"However, I actually have never seen an ill effect from mounting a linear; maybe it’s all not data, just lore."
The other link has this to say;
"If you have a modern AF SLR the answer is almost certainly "yes"."
Still thought of as not definitive,100% certainty. It is quite possible there is no effect, as many will attest to.
The page is also heavy on description of film and slide. So maybe out of date??
The best description on this page about when things are a problem is as follows;
"There can also be small autofocus errors in some cases if any of the lenses in the AF system are birefringent (polarization sensitive), which can happen if plastic lenses are used and they are under some stress. If you care about your pictures and your camera needs one, spend the few extra dollars and get a circular polarizer."
I'm hoping Pentax doesn't use plastic lenses. I can't say for sure, but I suspect most of their nigher end cameras have probably used non-plastic parts for some time.
Sorry, but until you can borrow a LP (no need to buy something you won't use, jeesh) and give us your first hand results, I really don't put a lot of faith in your opinions, over first hand experiences.