How to choose Canon 15-85 and 18- 135?

The two are definitely not in the same class. 1 and 15-85 are one of the top lenses in EF-s format. They have three UD (ultra-low dispersion lens) lenses and three aspheric surfaces, which can eliminate dispersion and glare well. Fine and sharp imaging, excellent transparency, perfect workmanship, image quality and focus, and so on. It's EF- And 18- 135 has only one UD lens, so 15-85 and 18- 135 are definitely not in the same class, but 18- 135 is just. 2. From the focal length, it seems that the focal length of 15-85 is shorter than that of 18- 135, but the former has an enviable wide angle of 15mm, which is a sharp weapon for shooting landscapes. Don't underestimate this small area of 2 mm, which will bring great shock to the scenery. This is absolutely not to be underestimated. Super wide-angle wide field of vision is shooting. 3, this lens uses a circular aperture, so it is also satisfactory for background blur; Although this lens is not a bull's head, the shooting effect is quite different from that of 18- 135. In short, when choosing a Canon lens, Canon's 15-85 and 17-55 are the first choices. For half-frame machines, 17-55 is better than 15-85, but if you upgrade the full-frame machine, 15-85 will be fine, and 15-85 will be useful.