If you only have room to pack one lens!
Wonderful broad range. Sharp. Well made.
EXPENSIVE. Heavy. Really stands out.
The Bottom Line:
If you have the need for this range, and the cash- Then do it. You will never be sorry!
This lens is HUGE. This lens is HEAVY. But- With a zoom range from 28mm-300mm, you are pretty well covered!
I have enjoyed using this lens in a variety of situations, but find that it really 'shines' in the Zoo- When I still want that wider angle that my other standby, the 100-400, just doesn't cover. With this lens, I can go all day without making a change- A significant advantage when you are out in the field.
A range like this brings you, on a crop sensor body, from Just shy of a 'normal' (44mm) all the way up to a decent telephoto, all with a push of the slide zoom. The reach is more than enough for some basic wildlife work, especially, as mentioned, at the zoo, where the 'critters' are a lot closer!
As for optical performance- It is an 'L' series lens, and it lives up to the name, for sure!! The pictures are sharp. You do need to realize that there are always going to be tradeoffs- When you construct a lens that has a range this broad, you are going to see some softness and distortion at the extreme ends of things. But- 'Soft' is a relative term- And I seriously doubt that you will ever get that comment from a photo taken with this lens!
This lens has an F3.5-5.6 apeture, so it is pretty slow. Not great for inside, or low light, although the Image Stabilizer function does help. Used outdoors, where it is intended to be used, it is great.
Autofocus is the fast and quiet Canon Ultrasonic Motor- Which means manual focus is always ready to go. This will save the day in a lot of situations, where you need to 'fine tune' the focus in a hurry!
The major drawback to this lens is the cost. At well over $2k, it is one of the most expensive in the Canon lineup. But, it is far cheaper and more convenient than carrying a bag full of primes with you! And, You don't have to change lenses all day long, eliminating dust in the lens/sensor, and keeping you from missing that great shot!
As with all L series glass, It's built like a tank, and can take a real beating. It uses 77mm filters. Includes hood, and carrying case, too!