Review of the Canon EF 17-40mm f/4L USM
Canon 17-40mm f/4 L (77mm filters, 16.7 oz. /474 g, about $850). .
Canon 16-35mm f/4 L IS (2014-today)
Canon 16-35mm f/2.8 L III(2016-today)
Canon 16-35mm f/2.8 L II (2007-2016)
Canon 16-35mm f/2.8 L (2001-2007)
Canon 17-35mm f/2.8 L (1995-2001)
Canon 20-35mm f/2.8 L 1989-1995)
Tokina 17-35mm f/4 (2011-today)
In this review I explain why I sold mine and purchased the Canon 16-35mm f/4 L IS.
1.) Excellent optics.
2.) Consistent results
4.) Light weight.
5.) Well made.
6.) The largest zoom ratio of any ultrawide: 2.4 : 1 (40/17 = 2.4).
1.) Unsharp corners
2.) Complex distortion
Why I sold mine
This is an excellent performing lens but its aging design could not keep up for the challenging sensor of my Canon 5DS R. 50 megapixels is a lot for most lenses so it's hard to fault the 17-40 however, there are now newer additions to canon's line up of ultra-wide zooms, hence why I sold mine and upgraded to the 16-35 f/4. It has better sharpness in the center and especially in the corners when compared to the 17-40. If you are using a lower resolution camera than the 17-40 is a lens worth considering.
USM: Ultra-Sonic Motor: It focuses silently.
f/4 at all focal lengths.
12 elements in 9 groups, including three aspherics and one of UD glass. UD glass is the same as Nikon's ED glass, which helps reduce color fringing.
7 blades stopping down to f/22.
77mm, the pro standard. Plastic filter threads. There's also a gel holder on the rear.
11" (0.28m) from the image plane
3.288" diameter x 3.801" extension from flange (83.5 x 96.56mm), measured.
16.705 oz. (473.6 g), measured, naked.
It's a great lens. For less money than many other lenses, it offers better performance.
Fast USM, can't go wrong here
Very accurate, few inconsistencies
Not well damped, sorry videographers
It's an f/4 wide angle zoom, so not much bokeh however it is smooth with 7 blades.
It has a rubber gasket on the lens mount to keep crud out of your camera.