Once I'm going 17mm.....

well I don't plan on going FF anytime soon, meaning not for at least 5 years. Beyond that, who can say, I say no now, but technology might bring an FF into focus simply due to better sensors that will likely have a higher dynamic range ( closer to film ) - not that I am complaining now, don't get me wrong. So, I may go the smart route, and rent which is relatively inexpensive, and that way I can really see what +'s and -'s they all have. Or, a used lens may pop up at a good price.

But, I will say, most pics will be of my kids, my daughter's b-day party is on sunday, and at the very least I will rent a lens for that day if I haven't made up my mind.

The advantage of an 8.2 MP camera is that if my composition is too wide, I can go and crop without feeling too bad. most pics will end up 4X6 in the end, so, no need to worry about resolution loss. But I can't go wider if I'm already too tight which is why the 17 is a must. I guess what I am adding is I don't mind too too much what the other end of the spectrum is for this lens, whether it 40mm or 85mm - so the price, speed, image quality, and f # will be the deciding factors, thx again all.

One thing to note is- though the 17-55 gives you more than the L there is an important note - the build quality is no where near it!

True, it is rather well built, but if you are in harsh conditions, you cant beat the L quality.
I am an officerin the military and require my lens to be well built. I'm now buying my own 17-40, and came to the decision after borowing a friend's. My dad has the 17-55, and I must admit I love it- it is very sharp, has great constrast and range and has a 2.8 aperture, but it just isn't built as well as the L and if you are a hiker, soldier, climber etc. there just is no other choice over the L - as stated before, it is a tank!

LightRules wrote in post #3091406
Frankly, the 1740 can't compete with the 1755IS on a 1.6x. Better focal range, IS, and f2.8. Totally different beast.

You're absolutely right! The 17-40 is weather-proof, better built, critically sharp with full-frame, half the price... totally different beast!

Also my experience is that in these focal lengths the IS isn't as important. A good technique can compensate (to a point) for the lack of IS.

But in the end its a question of how much you want to spend (unless, as I stated, it is the build quality which is important to you).

I think a test drive is a great idea. Try a few and see what suits your needs. If it's mud proofing and FF you need get the L. If it's optical performance coupled with low light capability get the 17-55 IS. If you want to save some money then get something almost as good for much less. Weight & reach may also be factors. Sometimes it can be something as intangible as a sense of balance in your hand.

Yea, first hand experience is always best - thats what made me choose the L.

Gidi Morris wrote in post #3096084
Also my experience is that in these focal lengths the IS isn't as important. A good technique can compensate (to a point) for the lack of IS.

But in the end its a question of how much you want to spend (unless, as I stated, it is the build quality which is important to you).

Good technique is important but coupled with IS it's even better, even at these focal lengths if the light is low enough and flash can't be used. That's why the 17-55IS is so popular with wedding photographers inside & outside. f/2.8 with 3 stop IS is remarkably effective in low light.