Canon 24-105mm or Sigma 50-150mm

I am trying to decide on a walk around lens for vacations and I am trying to decide on whether I should get the:

Sigma 50-150mm F/2.8
1. Large constant aperture 2.8
2. More reach 150mm (on a 30D)
3. Good price

Canon 24-105mm IS F/4.0L
1. Wider short end
2. Image stabilization (IS)
3. Better value retention

Both lenses have there “weak” areas as far as image quality at least from what I have read, I have not had any quality issues personally with Sigma or Canon for that matter although I only have one Sigma lens (70-200mm F2.8). The rest of my glass is all Canons (17-55mm f2.8IS, 24-70mm f2.8L, 85mm f1.8). Needless to say I like fast glass and I have no issues shooting at 800 ISO but usually I prefer not to go any higher with that being said the “IS” would be very useful for indoor photos I love it with my 17-55 but I would think with the smaller aperture (4.0) my ISO would remain high most of the time and I would lose the isolation properties of the larger aperture (2.8). I am really not sure how much I would miss the “IS” I compensate for the lack of “IS” with my 70-200mm with a monopod and I have gotten pretty good with my 24-70 hand holding at slower shutters speeds although I know at longer focal lengths it become more of a challenge at slow shutter speeds.

I am thinking I would take two lenses my 17-55 and 24-105 or 50-150 any thoughts?

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JM

http://www.photosbyjonathan.phanfare.com
http://www.photosbyjonathan.smugmug.com