I do a quite a bit of this type of stuff with my Pentax 67. The flash sync is only 1/30 of a second but I also picked up the 90mm F2.8 Leaf Shutter Lens (only available used) and the 165mm F4 Leaf Shutter Lens for Flash Sync Up to 1/500 sec. By far for candid wides all the way to tight portraits my favorite lens is the 90mm LS lens. The only downer is that you have to "cock" or wind the Leaf Shutter every time. Also, your flash sync cord plugs directly into the lens. Go, for the 67, I say.