alright just ONE more question, and I'll stop bothering you guys.
What are your thoughts on the Sigma 105mm Macro? and in comparison to the Canon 85mm?
Well, If you need Macro, then for sure go with the Sigma. If you want a faster lens, then go with the 85mm F/1.8. If you want to use it for portrait lens, I will take the 85mm.
Actually, at one point, I own both lenses. (sold the Sigma a month of so ago) I bought the Sigma (used but in brand new condition) and want to compare it with my EF 100mm F/2.8 non-USM macro lens. The Sigma lens is very similar to my EF 100mm lens. Since the 100mm lens is the non-USM version, so the AF speed on both lens are some what the same. Nothing spectacular. But it seems faster than the Canon 50mm F/1.8.
However, when it compares to the 85mm lens which is a USM lens, the Sigma 105mm lens AF speed is slow. But for a Macro lens, I will not worry about it. The build quality of the Sigma 105mm lens is good (after all, it is the EX series from Sigma), but personally I like the Canon better when compare the Sigma with both 85mm and 100mm lenses I had.
At the end, I'd rather keep my 100mm Canon (even though it is a lot older) and sold the Sigma lens (did not lose any money).
Don't get me wrong, the Sigma is a great lens. If I do not have the Canon, I will for sure keep it. But I will not replace the 85mm Canon with it.
Here is a sample shot I took with the Sigma 105mm. (This is part of a Notebook memory module)