Sigma 1.4x teleconverter

I have just purchased one of these,(haven't recieved it yet) I plan to use it with my Bigma and 180mm macro and would like know if its compatible with my pentax SDM lenses.
Even if I only have manual focus that will be ok, but i don't want to damage anything either.
Has anyone used one of these TCs with thier Pentax lenses and what is the pic quality like. : Thanks

If it is the APO version I did read somewhere that they can only be used with Sigma lenses, and only certain ones of those at that.
That's why I went for the Tamron 1.4X.

May be totally wrong though, it has been known

Edit reason : Missed an "F"

You can use the Sigma 1.4x on many lenses. However, it has a protruding element and you have to be very careful to check that the lens you want to use it with has a recessed rear element. The Bigma doesn't, which is the main reason that that lens has a limiter switch. If you want to use the TC with that lens you must put it beyond the limiter first, engage the limiter and only then mount it to the TC.

It works fine on the 180mm as that has a well recessed rear element.

The Sigma TC's don't have the PZ couplings, so SDM will not work through them. It does have the normal screw focus coupling.

I also have a Kenko 1.5x TC which works with just about any lens, but you have to be careful to get the slightly older one that has the PZ coupling, the newer ones don't, if you want SDM.

Pentax stuck a converter on their road map in January but more nothing has been heard about it

IMX, though, putting any TC on the bigma was a disappointment, especially with the lens at 500mm as you struggle with light and stability. Sticking a TC on the 180mm macro does work surprisingly well as the lens is so sharp you don't lose much in IQ. It does make the setup just that little more cumbersome (and heavy), though.

I have one of these. Works well with Bigma, and should be great with your sigma 180.
cheers
bb2

Clarky - I used to have more Sigma lenses than I do now, and in my experience, it didn't fit anything not on their list of allowable lenses.

(SIGMA EX Apo Tele Converter Compatibility chart for SIGMA brand lenses)

It will fit a couple other lenses but you need to be very careful of the lens rear element touching the front element of the TC. I've checked to see if it could fit non-Sigma lenses, and the 5 or 6 that I've tried are definitely not usable. Either the rear element sticks out too much, or the diameter of the flange thing (just inside the mount) is incompatible...

Thanks guys, some interesting and valuable advice.
I wasn't aware of the rear element restriction it has with some lenses Cheers.

There is a Pentax 1.7 on Ebay at the moment......£122 at this present time!