Wich TC for a sigma 150mm macro

Hi, wich TC are compatible with the 150mm sigma macro. I try to use the Kenko 1.5X, but this one have difficulty to lock with the AF ON.

The Kenko 1.5x is an older design, you can do better. Why not a Sigma EX DG 1.4x TC? Tamron SP 1.4x TC would be my next choice. Why are you using AF? Most people do not use AF for macro work, and yes, any TC will slow AF down.

I've had great luck with the tamron sp 1.4 and the sigma 1.4, both work GREAT.

Usualy for static macro shot I use the MF with AF confirmation on the 40D, but also want to use the 150mm as a short telephoto for non macro work. Strangely my kenko 1.5 work flawlessly with my 100mm f2 and the AF lock very fast. On the 150 macro lens the AF go relatively fast but at the end it's spring back and forth and sometime stop to spring and lock on the subject. The Tamron SP is it the pro version or the older like the 1.5. All my nature stock are stolen recently (1D3/400f5.6/70-200 f4 IS/ Kenko pro 1.4), so I rely on my back up: a 40D+ a 100mm f2+ a this new 150mm as a temporary telephoto during the dealing with insurance.