I think the question was an interesting one, even though the intent was slightly different. This has turned out to be a discussion as to whether lenses behave equally in all mount versions.

The question of the mount is interesting in another way as well, as the Pentax K bayonet mount has proved itself to be a very superior one that has been able to be developed as camera technology has demanded. Originally conceived as a high quality stainless steel mount of wide diameter (45mm) it has survived the test of time extremely well.

By comparison, the Nikon mount is narrower and the solutions to various demands have been possible but perhaps a bit strained...the external meter coupling of the original version was very crude, although AI and AI-S developments improved on that. Early Nikon lenses had to be returned to the factory to be upgraded, which was a major exercise.

Canon actually had a superb manual focus mount in the Breech Lock version, where no rotation of the lens was needed and hence there was no wear of the interface. This was simplifued at some point to a standard bayonet and then had to be abandoned completely to cater for AF.

I think mounts could make an interesting discussion of their own.

The only way we ever really get a proper assessment of a lens is to try it for ourselves - everything else is a guide unless it's a proper Lab Test that explores a lens's characteristics in some detail, and of course we are able to interpret the results.

So, for example, we can infer reasonably certainly that the Pentax Limited lenses are a bit above the norm, but whether or not they suit our photography is something we discover for ourselves.

Flodden Field, site of the famous battle.
[IMG]http://i240.photobucket.com/albums/ff250/johnriley1uk/027FloddenField2.jpg[/IMG]

That's fine, and many film lenses do work well with digital, no-one is denying that.

I can't really comment on the Canon lens in question as I'm not familiar with it.

Pentax make APS-C format DSLRs whereas Olympus make 4/3 System DSLRs, so I expect this was the reason for the comment about the formats being different.

The Olympus cameras are potentially smaller because the format is considerably smaller.

The Takumar (bayonet) lenses were in fact coated, with conventional coatings and not the SMC treatment.

I wouldn't advise that - the e-mails are sent out randomnly, but by replying with anything you identify an active e-mail address and your IP address.

Complicated, isn't it?

That would assume the same pixel density for the FF and APS-C sensors we were comparing.

So if both, for example yielded image sizes of 4000 x 3000 pixels, then both sensors will yield the same size of print. Obviously in this case the pixel spacing, or density, is not the same for the two sensors.

We can no longer think only in terms of physical dimensions only.

I have purchased items from this company, via Amazon Marketplace, and they were just fine.

Before we dismiss them out of hand, at least look at the Amazon Marketplace Guarantee and see if you find it reassuring enough.

And, of course, the feedback given by Amazon customers.