Recently I bought Canon 70-300L f/4 - f/5.6 IS USM lens. And here is my brief opinion on it.
What really amazes me in this lens is image quality. For me image quality is the most important factor and it was actually the main reason why I decided to get this lens.
Canon 70-300L produces images with great sharpness (really!), very nice contrast and colours.
Another interesting thing is that this lens is pretty compact. Most of the long tele-zooms from Canon and other vendors are very long. 70-300 is just slightly longer that 24-105L lens. If you're familiar with that lens this tele-zoom will be really easy to handle. It's also lighter than most of the Canon tele-zooms (still weighs 1 kg) but looks as solid as all other white L lenses.
Moreover focus and focal range rings are well-placed and works smoothly yet allow for very accurate adjustments.
So are there any drawbacks or maybe it is an ideal lens? Unfortunately there are two and the first of them may disqualify this lens for many photographers.
It has aperture of f/4 to f/5.6 at 300 mm. For me it isn't that important as I don't often need it and shooting mainly landscapes and architecture I hardly ever use larger apertures than f/8.
The other is that it's impossible to use tele-converter with it. I don't use so again it's not a problem for me.
- great focal range
- fantastic image quality
- very good image stabilization
- looks solid
- compact size
- maximum aperture of f/4 to f/5.6
On the left you can see 3 sample photos I took with this lens with 1st one being HDR post-processed in Photomatix Pro 4.1.
For samples photos see following pages: