Considering Canon 70-300 L to replace Sigma 100-300 f4

bigfatron wrote:

The title says it all. Currently got a Sigma 100-300 f4 EX and am giving consideration to buying the Canon 70-300L to take its place. From what I can gather then the pros and cons of this are thus..

Pros

• Reviews of IQ and AF responsiveness on the Canon seem to be universally excellent and many seem to place it right at the top of the tree of L telephoto zooms in both regards
• 4 stop IS capability versus none at all
• Environmental sealing
• Gain 30mm on the short end
• 400g less to lug around and a smaller physical package

Cons

• Trade constant f4 for f5.6 at the long end
• Lose ability to use a TC, in any reliable sense at least (I do have a 1.4 for the Sigma but it gets used a tiny percentage of the time)
• Would need to purchase a tripod collar if I decide I need one (although it seems 3rd party versions are available at less than the ransom Canon want for their offering)

My typical applications have been birds/nature, zoos, airshows and occasional sport usage (generally daylight outdoors stuff). Currently i'm shooting with a 7D.

What specifically appeals with the 70-300? If the IQ feedback is true (although you never quite know how precisely objective information you see is) then it should improve on what i've got. Although the AF is reliable and fairly swift most of the time with the Sigma, the 70-300 sounds almost bulletproof in most reviews. The smaller package and IS should hopefully alleviate the current penalties of almost an extra half-kilo of lens, gain back some bag space plus not having to lug a monopod about as often. Cost shouldn't be too much of an issue, especially if the Sigma and TC are sold on.

Some people have suggested the 100-400L, although the IS is first gen, the pump zoom doesn't appeal and i've heard mixed things about them beyond the 300 mark anyway. At least head to head tests are available for this and the 70-300L and the 70-300L seems to fair much better where the two overlap.

Given the Sigma was discontinued slightly before the 70-300L came to market then its hard to find direct comparisons of the two lenses. I've only come across a couple of posts where people have owned both and they generally favoured the Canon unit. So i'd be intrigued to know if anyone else has experience of both bits of glass and can pass comment?

Dont even think twice!  the Canon 70-300 L. is a fantastic lens, super sharp and terrific IS. My favorite lens actually.