I bought the CANON 28-135mm IS lense 3 years ago as a travel lense, but like many other viewers, I have become to realize the limitations of this lense at both 28-35mm and at 100-135mm, despite stepping down to F8. Naturally, this is common with zooms covering this range. But I find the results are unacceptable. Around the 40-90mm range, the sharpness is excellent with its sweet spot around F8.
Also I have become increasingly worried about the dust particles which are gradually building up inside the lense.
So I am seriously considering purchasing the (OLD CANON 28-80mm F2.8-4 L lense) second hand, which is going for around $300- $350. I would really appreciate anyones advice on this old lense and do people think that it is worth changing, since sharp images are what I am looking for?