Hi, I'm 17 and turning 18 next month.
I'm blessed to be able to have parents and jobs that can afford me the gear in my sig list over three years.
Like you, I started off with a rebel body, and "planned to move to FF". That didn't come for 2.5 years though (1.3 crop came in exactly 2 years, followed by FF later on), and I definitely wished I had gotten the 17-55 then instead of the 17-40L.
Since you're on a crop, I highly recommend the 17-55mm like the others have said. I definitely know how difficult it is to muster the cash for higher end lenses, and not getting a lens that is badged as "L" for the same price might be getting to you. But trust me, the 17-55 is easily the best standard zoom lens out there for crop, and is easily sold without much loss in the second hand market.
And talking about second hand markets, why not take a look there?
All the best,
Another 17yo shooter (:
Couldn't have said it better.... pretty much everything you said is exactly what is going through my head. Seems like everyone has pretty much ended my contemplations between the two 'L' lenses, which is a relief. And happy early birthday! My 18th is in February...
Also, in regards to upgrading to FF, y'all are right. College will get in the way and I'll probably just forget about upgrading. I do hope to take some type of photography class while I'm there though, maybe get some experience with different bodies and lenses.



