Hi, I have around a TCON17 that I used with the LX-5. So I just tried to put it in front of a Nikon 50/1.4 and it works great: I have an equiv. 170/f1.4 for free or a 122/1.2 with the focal reducer The only problem is that the beast, the TC I mean, weights 260 grams! and it makes the focus very hard to use and I suspect that it could damage the focus mechanism in the long run. I have to sustain it with my hand to be able to focus normally. So I'm thinking: is there any cheap 50-80 something lens without this problem? I think I should look for internal focusing lenses but maybe the zoom type is also relevant. Otherwise I could try to build something like this: http://static.photo.net/attachments/bboard/00O/00O3tQ-41071584.jpg BTW: do you think it could work fine on the sigma 60/2.8?