[Clavius]

Anybody tried this gadget:

AF Auto Focus PK Macro Extension Tube Ring For Pentax PK Mount Camera KS1 KS2 K3 K7 K50 K-50 K30 K10 K5II K5 Kr Km Kx K1000 K20D
http://s.aliexpress.com/7JnayaI3
(from AliExpress Android)

Seems to good to be true, so it probably is.

I want to use something like this with my DFA 100 2.8 to increase enlargement. But for some reason I don't dislike AF with macro, so it would be nice to retain it.

[othar]

If the picture isn't photoshoped it might even work

But if I am not mistaken the longer the focal length of your lens, the fewer the impact in magnification you gain with the same extension tube.
So with 100mm you probably need 2 or more of these tubes.

[Clavius]

If the picture isn't photoshoped it might even work

But if I am not mistaken the longer the focal length of your lens, the fewer the impact in magnification you gain with the same extension tube.
So with 100mm you probably need 2 or more of these tubes.

Ok, luckily I also have the DA35ltd to play around with then.

[Lake]

It appears to be the same manufacturer as my 2X auto focus teleconverter. I haven't had any problems with fitment or operation. It's worth buying.

[robthebloke]

I own that extension tube. It works, but it's not without problems. Attaching lenses to it can be painful. Manually focussing a non-quickshift lens is not possible.

[Clavius]

Thanks guys, I'm going to go ahead and just try it. Can't really go wrong for that tiny price. As long as it won't damage my cameras or lenses...

[swiz]

autofocus with a macro lens at 1:1 magnification or higher is quite difficult. I am not familiar with pentax bodies, but if they posses the ability to execute a focus stacking script similar to magic lantern in an eos body, then you can manually over ride the lens af and use the lens and body on a tripod to focus stack. That would make an adapter such as this extremely useful as you are no longer relying on internal AF.