I use EOS cameras and find teh 28-135 IS USM great. At the longer end you still get good selective focus and the lens performance is superb. The image stabaliser really helps in low light too. I will soon be adding a 70-300 IS too. I have really been impressed by the work of Annabelle Williams (UK based porttrait/wedding photographer) and whe mainly uses the 70-300. Not sure what make your bodies are?

Tom

Tom