WANTED A-Type 2x TC for experiment...

WANTED due to 'RioRico's recent post on Pentaxforums...

"here's an experiment to try: Get a DA18-55/3.5-5.6 kit lens. Get a cheap used A-type 2x TC. Remove the element from the TC and re-install it REVERSED! Your TC is now a 0.5x WC, a wide-converter. The kit lens becomes a 9-28mm f/1.7-2.8 zoom! WOW! The trick is to get the TC/WC element placed exactly right. Good luck"(RioRico, pentaxforums, lens discussion, cheaper wide zoom options).

I'd really like to have a go at this... Never tried anything like it before...
Anybody got a spare I could butcher??

I've got a Kenko 7 element one (PKA, not AF) with some coating damage to the rear element. Looks as if it has suffered heavy cleaning.

Yours for £20 delivered (and an account of how you get on, obviously!) if it's of any interest.

Hmm. Without wishing to rain on anyone's parade, this sounds a bit like someone is talking rubbish.

I'm happy to be proved wrong, but lets think about it- a teleconverter effectively works like an optical crop device- it takes what image is there at the back of the lens, and enlarges the center section. It can't force the lens to draw in a wider view than is there in the first place. The only wide angle adapters I'm aware of, are those that go on the front of lenses, and draw in a wider view of light than the lens usually gets.

I'm pretty certain that users have tested the 18-55 on full frame bodies, and found very heavy vignetting around the edges- there simply isn't a wider view to be drawn on (at the back of the lens).

I suppose the fundamental problem is- if such a device was possible, don't you think it'd be commercially available right now?