I’m looking to purchase a new lens for my 80d which obviously has a 1.6 crop factor with a full frame lens. I currently use an EF-S 18-135 USM, I would like to purchase the classic 24-70mm f2.8 but I’m guessing that the 24mm would actually result in 38.4mm considering the 1.6 factor. Because of this would I be better of getting a 17-40 which in theory would be 27.2mm because of the crop? thanks
Your right that the 17-40 (or a 16-35 would be better if you want to go wider than 24mm. I myself bought the 17-40 as my first main lens purchase on my 20D back in 2004 when I started buying canon, it is a great lens value for the money. But before I can recommend that be the next lens I think you want to also think bigger picture about the other lenses you may want. Some like the 24-105 because the never really change it. Wedding photographers used the 24-70 2.8 as a staple because it covered wide enough for some group shots and zoomed to a nice portrait length as well as being fast at 2.8 to handle lower lighting. I prefer the wider end of the spectrum and so I chose the 17-40 and have complimented it with fast primes afterwards to add extra reach for shooting portrait length.
