Originally posted by phoebus I'm not sure comparing 1980s cheap teleconverters with what a Pentax FF may provide is particularly valid.
Here is DA*200/2.8 with HD1.4x:
I’ve had various tele-converters over the years (my first was actually part of the lens, a Tamron Twin-tele 135/200) and their performance has often been disappointing, with a few exceptions. With B&W film, they were useful if not wonderful, and colour aberration wasn’t too much of an issue.
The F 1.7x-AF has been a major exception, in my experience, not least because of its ability to add AF to MF lenses, but because it was optically superior to the ones that went before. I understand that there were dedicated Pentax tele-converters for particular star lenses, but I’ve never been lucky enough to own any of them.
Nonetheless, none that I’ve owned have worked particularly well with zoom lenses, and some have been downright awful.
Your shots with the HD1.4x give me hope that the next one from Pentax will be even better.