Like every wide-angle it shows an amazing DOF; so, getting it to produce a decent bokeh is a little tricky, even at f/4

Great for landscapes at 17mm and has enough bokeh for portraits at 40mm f4.

Thanks to 7 diaphragm blades, this lens can produce very nice bokeh at 40mm (blur effects).One of the most cited weaknesses is the f/4 aperture

After all, the bokeh becomes the only reason that the fstop is so important(i wouldn't discredit this because smooth bokeh makes portaits great) , as the difference between f4 and f2.8 is going from about ISO 200 to ISO 400, and with the dramatic increases in high ISO perfomance, it is likely you will not greatly notice the difference.

If I want a nice bokeh at a short focal, I will use my 35mm f/1.4.If you want to see real situation samples, just check my blog and website:[

It is tack sharp, captures great color, has wonderful bokeh and is as wide as I will ever need

So if you don't need the extra f-stop, go with this one and save yourself $700.On 35mm film or the 1Ds, you'll see more vignetting with this lens, but the images are still excellent, and this lens has less flare than the 16-35.The 16-35 is marginally sharper near the 35mm focal length, and does have much better bokeh, if that's important to you

My 17-40 is incredibly sharp, the bokeh at f4 is excellent, and the colors are perfect

Bokeh is sweet when wide open, the focus spot on - and I do mostly dog photography - action primarily,

At f4 the bokeh is pretty nice

Nice, smooth Bokeh!2

This lens has beautiful bokeh IMO and is every bit the equal, again IMO, of the 16-35 f2.8 L in every respect other than speed (f 2.8 vs f 4.0).

Also you'd be surprised how much nice bokeh you can get at f/4.

In contrast, i love the photos from my not-L-glass Canon 100m macro or my similarly "inexpensive" Canon 70-200L f/4.0 (which has amazing color rendition and excellent bokeh).