as for using the 55 micro 2.8 - the 600 to 800mm of extension required to get the 10x is FINE. It's not an IDEAL setup but I've gotten stunning results with a 180mm sironar at 1:1 with it. Just a Sinar P2 clamped to two rall clamps bolted to a masonry wall. Pretty solid especially since everything is being shot with strobe...