Hi, I'm having a macro Sigma 105mm f2.8. Two things that I don't like about this lens: 1) noisy and slow in focus (although with f2.8). 2) During focusing process, the inner tube keeps getting in & out (I believe that makes it slow & noisy). Now, I'm thinking about changing to Sigma 150mm f2.8 macro lens. So my question to you is that does this 150mm lens have the above two things that I mentioned above? Thanks.