I have many Contax CY lens. I like the fact that they are mostly 55mm filter size. I also have the 300/3.5. Contax CY lens at f2.8 level are affordable and good for value. Their 1.4 series are all over-priced. Using 180 or 300 Contax, the biggest problem is handshake. Therefore I am grateful to use it on Z7 and with proper adjustment I can get IBIS, it makes using these long telephoto so practical and useful.