My main walkaround lens is the 24-105/4L IS and I like it a ton, but I truly miss having any decent low light capabilities. The 12-24 has been great on vacations for capturing panoramics and city scapes from close distances. But, I'm thinking it would be worth the trade of giving up 5mm on the short end for a twice as fast lens with IS.

The 17-55 has been reviewed to have L-quality optics and I think I'd find I use it more than the 12-24. I'll probably pick up the Canon 10-22 at some point just to have the ultra-wide back in my quiver.

Thoughts?

Immediate applications will be a cruise I'm going on this summer to Rome, Greece, Turkey and Naples.

but I think you may want the wide capabilities in the city. Tough call.

Well, it depends on what and how you shoot. I'd say the 17-55 is wide enough unless you really love very wide angles. I used the 16-35 on the 30D and found it to be wide enough for my needs (mostly landscapes and cityscapes). I also had the Canon 10-22 but it was too wide for me, I didn't find enough use for the 10-15mm range, but it's all about what kind of photography you're interested in. For "normal" landscapes and cityscapes 17mm is reasonably wide even with a cropped sensor.

And you can always stitch two or more images together with Photoshop or Autostitch to get wider views.

I would do the switch. The 17-55/2.8 is a very nice lens and you get more low-light power.

And keep the wide angle until you're ready to switch to the 10-22? Seems to be you'll probably end up using the 17-55 most of the time, and leave the 24-105 in the bag or hotel. May as well hold onto a completely different lens in case you want to shoot something different.

The 24-105 is fantastic lens that's far more versatile than the 17-55 could ever dream of being. It's probably the best walk around lens Canon has ever built. It's only downside is shooting people in low light, but 2.8 isn't fast enough for that anyway.

I have way too many shots in that range to give that up. My next lens up is the 100-400 and that is truly a specialty lens that I generally do not travel with. So, I can't really see myself going solely with the 17-55.

outdoors this isn't a problem. oddly, I very rarely use it indoors, as my 24-70 is fine for indoor people photos.

back in the sigma 24-70 debacle, I had to use the 10-20 to shoot a band, and it was pretty horrendous, shooting in a dark bar with a high black ceiling and one flash..

I'd trade the 24-105 for the 24-70 f/2.8 if it was me, and keep the tokina, and pick up a 70-200 for the long end. Yes, it's a lot of lenses to drag around, but works well..

But, I already have the 100-400 on the long end and the 24-105 has been superb. Most of my main walkaround shooting is daylight and I find the 70-105 range very useful. When I find myself wishing I had a faster lens, it is not usually in the 50-200mm range. More often, I'm looking to do a night time panoramic, or an indoor low light shot of people close by, or, most often, night shots at a ballgame. 200mm isn't enough for the cheap seats I can afford anyway.

So, I'm quite content with teh 24-105 as my main lens. It's an L, it's sharp, it's got a very useful range, it's got IS, and it's 40% lighter than the 24-70.

just bought the Tokina 12-24. It was an impulse buy. Great quality, great images, but WA isn't my thing... I NEED a 500!!

It's half the price, and close performance wise in the tests I have seen.

I have had one for a couple months and am quite happy with it, especially considering the price.<ul><li><a href="http://www.the-digital-picture.com/Reviews/Tamron-17-50mm-f-2.8-XR-Di-II-Lens-Review.aspx">http://www.the-digital-picture.com/Reviews/Tamron-17-50mm-f-2.8-XR-Di-II-Lens-Review.aspx</a></li></ul>