Right now i only have one lens - the 18-135
Since i want more reach i decided my next lens will be telephoto.
I was thinking about the 70-200 f4 IS but today i was shooting with my 135 and it turned out to be really far away from my subjects. I cant afford buying an 2.8 telephoto and i want both versatility and reach. So i thought about the 100-400, but i don't know if the image quality will be extreme.
1. Is the image quality of the 100-400 any better than my 18-135?
2. What about autofocus? How does it compared to the one in the 70-200?
3. Does this lens also work for portraits?