Hi All,

I have an EOS 7D which was purchased with the 18-200mm kit lens over a year ago. I mainly purchased this camera for sporting events (equestrian and motor sport) and to try my hand at a spot of birding. I soon followed up with the Canon 50mm f/1.8 for a bit of experimentation and also a Sigma 150-500 which I have been very happy with and find I use almost all the time.

I'd now like to extend my photographic subjects to people, candids and portraits. Although the 50mm f/1.8 does a good job for shots I can plan, I still find myself struggling for family gathering and party shots that require a wider lens on my cropped camera.

So my thoughts are:
1. Tamron SP AF 17-50mm f/2.8 XR Di II LD IF
2. Sigma 17-50mm f/2.8 EX DC OS HSM
3. Canon EF-S 17-55mm f/2.8 IS USM

I'm impressed with the bang-for-buck I got with my Sigma 150-500 and I'm not sure I'll appreciate the extra money spent on the Canon 17-55 at this stage, which pretty much narrows it down to the Siggy and the Tammy.

The OS is the biggest functional difference between the 2, but I'm after some feedback as to whether its needed on this length lens, when hand holding and shooting portraits.

A grey Tammy looks achievable for around $400 (local $550)
A grey Siggy is around $700 (local $850)
A grey Canon is around $1300 (local $1700)

I've read quite a few reviews and I'm looking for your input to confuse help me some more please Any feedback is welcomed.

Thanks.