Sigma Lens Tests at 180mm:

55200 DC f4-5.6 DC

70200 f2.8 EX/HSM

80400 EX/OS

180 f3.5 EX/HSM

In this test, I compare the 55200 DC, 70200 f2.8 EX/HSM, 80400 OS/EX (OS off) and the 180 f3.5 EX/HSM Macro at 180mm at infinity wide open through f16. I used a sturdy tripod and MF with Nikon magnifier. Conclusions: No surprises here. The 180 f3.5 is very good across the board; even at f22, not shown, it looks useable whereas the other three are not (f22 not shown). However, the amount of times you need f22 is miniscule IMHO.

f2.8 180mm --- 70200 --- 180(f3.5)

f4 180mm --- 70200 80400(f4.5) 180

f5.6 180mm 55200 70200 80400 180

f8 180mm 55200 70200 80400 180

f11 180mm 55200 70200 80400 180

f16 180mm 55200 70200 80400 180