Oilman wrote:
The 18-135 mm is a middle of the road lens. Image quality is limited both by the quality of the glass and by simple physics. The greater the zoom percentage, the harder it is to design a lens that does not distort the image in some way. The 18-135 mm lens does an adequate job, but you see very few professionals using super-zooms
In contrast the 17-55 mm and the 15-85 mm are L class lenses. The glass in both these lenses is the exact same glass as is used in the L lenses and the image quality is also the same. Since neither of these lenses is a super-zoom, there is little nor no distortion associated with the zoom function. These lenses are both an order of magnitude better than the 18-135 mm and are a clear upgrade.
What you gain is clearly superior image quality, what you lose is the convenience of a super zoom. So what is important to you? I bought the 17-55mm four years ago and never looked back. It is my “walking around lens” and 80% of the pictures I take are with this lens. I like the fact that I can open it up to f2.8 and most of all I like the image quality. When I need a telephoto lens, I put a telephoto lens on the camera. I have the 55-250mm, the 100-400 mm and the 500 mm prime. I consider changing lenses to be part of this game and I don't mind carrying extra lenses. I need the exericse (LOL). The convenience of a super-zoom is a non-issue for me – I want image quality.
Question 1: What do you want? If you like convenience, stick with the 18-135. If you like superior image quality AND a fast lens, go with the 17-55mm. If you want a bit longer reach than 55 mm and superior image quality, go with the 15-85mm.
Question 2: What is your budget? The 17-55mm will cost your around $1050 USD, the 15-85mm is $800 USD. In contrast the 18-135 mm sells for around $500 USD – less than half the cost of the 17-55mm.
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The first camera bag you buy is always too small
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