|Message from Alex McCreath
Hi. If you take the time to have a look around you'll note two themes: aviation and equestrian. I currently use a Canon 40D DSLR and various lenses. However, my two favourite lenses are the Sigma 100-300mm f/4 APO EX DG HSM and Canon EF 100-400mm f/4.5-5.6L IS USM.
Sigma 100-300 EX
I have never regretted buying this lens. My purchase was based on the plethora of info in the web shouting its virtues, and cost (The Oz agent matched internet prices!). In my opinion its IQ is *superb* at all focal lengths and, for my copy, at apertures between f/4 and f/16. I can't emphasise how much I enjoy using the lens. For me, its weight isn't an issue and I easily hand held it at airshows for the whole day (it does get 'heavy' after a while, but not too much so). It takes a TC very well with only a miniscule reduction in IQ, a minor reduction in focus speed and the loss of one stop. The Sigma is my equestrian lens.
I had intended to sell the Sigma when I got the Canon but just couldn't bear to part with it. I need the Canon's IS for shooting prop aircraft, to obtain prop blur. It is also helps keep things steady when I'm trying to obtain background blur. Generally, the difference in IQ between the two lenses is negligible (with a slight edge to the Sigma, if anything, wide open) and the focus speed is comparable on both (except when the Sigma has the TC on = slower). I am a big fan of the Canon's focus limiter and long reach - a must at airshows - and the versatility and flexibility of a zoom. The Canon is my aviation lens.