Sigma 17-50 or stay with my 18-135

Headed to Disneyland next week; we live in Northern California so we are very frequent visitors.

Having read about every thread I could find using the search function I am still torn about going with my current lens setup; or adding the Sigma to get better low-light functionality over the kit lens.

I have settled on the Sigma over the Canon for the same reasons that lead me to choose the 70-200 OS vs the MK II; Sigma offers 85% of the functionality/Quality for 60% of the cost.

Will adding the f2.8 really make that much difference over the f3.5 on the wide end; I believe that most of the evening shots will be at the wide end? Still have a day or two to decide before the shipping clock runs out. - Love Amazon Prime

I took my 17-50 to europe and it was perfect, if you have room take a small prime like a 30 1.4 or 28 1.8 and you should be fine. 2.8 is really needed inside the attractions, f3.5 you would need your flash. Leave the zooms at home, your back will thank you.

+1 to the above the Sigma 17-50 2.8 OS is a truely great lens.

+1 for me on SIgma 17-50. If I could just bring 1 lens going to Disneyland trip, it is better performer in low light especially from dawn to evening shots. No question much better IQ & faster AF. Bring your 55-250 with you if you want more reach during daytime shots. Good luck with your decision

I know this is kind of an old thread, but what lens did you finally choose? I'm asking because I'm thinking of selling my 18-135 and getting a Sigma 17-50 instead...

Sigma 17-50mm 2.8 OS = Def. stays IMO

I had this lens last year and it was the best all around lens !

This is one of those "Gotchas". The EF-S 18-135 gives you that fantastic reach and it spoils you. It's a very capable walk about type lens- great for a one-lens walkabout solution... the 17-50 OS on the other hand is better in low light, very accurate, sharp. Sometimes, I wonder if I should have wandered into the middle and picked up something like a 15-85.. Personally, most of the time- outside- I don't find 50mm long enough- no where near.

I have a 17-50 OS- and it's mainly relegated to indoors/ low-light type shots- and I like it because it works well with the 7D- providing very accurate f/2.8 shots. It's really a wonderful lens- but for most outdoors type stuff- I find it a bit short. I kept my 18-135 just because of that fact. I thought the 18-55 was short- and I hated it- not because of the variable aperture, - but for its short range. I knew what I liked. So, I keep both in my kit- a 18-135 for daily walk about- and 17-50 /f2.8 OS for night time/indoors type stuff. Two different lenses for two different purposes.
Now, as for your situation- with 2/3rds of a stop and only concerned at the wide end-I'd probably bump up the iso or down the shutter speed or a mix- (shutterspeed down by 1 click and iso up by one click )- and you've basically negated the difference ). The only other thing that you haven't negated- is perhaps that f/2.8 is a little more accurate for center point on a 7D. For shots at a distance- less important. If you need to use fill flash- also less important. Naw- I probably would not change it out in your case. But a lot should depend upon how you use your 18-135.. If you are on the wide end mostly- then 17-50 yes.. If a mix- maybe keep both ?

If I were you, I'd probably buy the 17-50- because I've been thinking about it so much. then take it out on such an outing. Take a permanent marker or a notepad and pen with you... Every time that you get ready to take a picture and wish that you wished for a longer lens at that time, put down a tick mark- and at the end of the day- see how many shots you got like you wanted and how many you wished that you had something longer.. then you will know. As far as the silly remark- step a few feet forward- that works for subjects that are close to you- but if you are taking a picture of something in the far distance- stepping forward a few steps makes little difference- sometimes- raw focal length rules!

For a Disney trip, you will need more reach during the parade but not so much elsewhere. How about two lenses solution in the evening only? I would suggest either Tamron 70-300 or Canon 55-250IS with Sigma 17-50 OS.

You'll get better low-light and sharpness.

The 17-50 is a fantastic lens.