I am aware of at least some of those who have been involved in an exchange of PMs.

A PM is exactly that - Private. If it offends or contravenes the forum rules then please advise a Moderator accordingly so things can be looked into.

Even selectively quoting a PM is not a good idea and hardly provides a mechanism where all sides can be fairly heard.

The advertising. Now and again some useful information.

Try on a tripod, aligning youe eye carefully in the viewfinder. Hand held we can waver about a fair bit, so it's hard to know exactly that a subject is centred.

Having said that, your subject looks a long way off to be a camera fault. I'm not sure that it's possible for an image to be that much misaligned because of the camera.

This is not the place for religious or political arguments, it's a photographic forum.

100mm. The 50mm is better suited for document copying, and the 35mm even more so, at least the way I work.

The 100mm enables a better working distance for most subjects, which is probably why the number of 100mm Macro lenses available far exceeds the number of 50mm ones.

I was really comparing Pentax prices with other marques, not with independents. However, I understand that you have in mind that Tokina and Pentax worked together on some designs. To be fair, we don't know what form this cooperation took and it's quite clear that the two makes are not just rebadged versions of each other.

Well it can't and when it is "exposure errors may occur" so there seem to be technical reasons. I did notice someone mention that the metering coupling was non-linear in some designs and linear in later ones, so perhaps that's the problem. It's easier to use A lenses and later and perhaps the development costs for enabling the relatively few older lenses that will be used was not deemed to be cost effective.

As things stand compatibility extends back some 30 years at least, and that's pretty good by any standard. You can use lenses going back almost 50 years if you want to but it's not unrealistic or unreasonable to find that in that case there are some restrictions.

Or to reduce costs by removing support for long obsolete lenses (in the wider market's sense), or to make room for other technological developments that mean the mechanical coupling can no longer be accommodated.

You would probably be better using rechargeable NiMH batteries, or Lithium cells. If you have been trying Alkaline batteries, they may not be suitable.

The general rule is Pentax images only, for obvious reasons.