Go tilt shift! Or at least be prepared to correct in post if not, at the cost of resolution and how precise you can get your composition. For professional work you really need the 17mm and 24mm at LEAST if you want to compete, imo.
The 17-40mm is okay... Soft at the edges particularly at 17mm, but not unusable. Better stopped down but never great. Performance improves as zoomed in; so does distortion, which is an issue but not terrible at 17mm.
Gatormanred said:
Some advice please....I have a 5dc and mainly use a 24 - 70 Mk1 but I am in need of something wider for internal shots of houses etc and was thinking of the 17-40L. Is this my best bet on my budget of approx €600 or is it worth looking the Samyang 14mm or any others?