The second lens I purchased after buying my first full frame DSLR was this 16-35mm f/4L.  I was absolutely in love with my 24-70mm f/2.8L II, but I really missed the ultra wide filed of view I enjoyed on the 10-18mm f/4.5.  That lens was practically glued to my camera on my recent road trips through Colorado and the American Southwest, and while the 24mm is approximately 15mm on an APS-C sensor, it just didn't have that extra "stretch."

Enter the 16-35mm option.  I agonized over whether to go with the f/2.8 or f/4 version for weeks.  I mean, I certainly thought it would be great to have f/2.8 for astro landscapes...right?  Then I realized I only took at most one or two Milky Way shots a year.  It just didn't make sense to go with a lens that was double the weight, more than double the price, and with no Image Stabilization if my shots were all landscapes shot at f/7.1 and higher.  The weight savings is incredible, and the performance is unreal for a $1,000 lens.

The f/4 aperture admittedly doesn't give any bokeh at all.  But that's frankly not what this lens is all about. Instead, I frequently stop down to f/8 - f/10, and if the scene is dark I'm usually on a tripod for long exposures anyway.  The IS is definitely very useful and makes handheld 1/20 second shots more than doable.  Check out my sample images below, all shot with this lens, including some of my all time favorites. 

I really have no complaints with this lens whatsoever.  It's perfect for backpacking and also takes filters well, even at 16mm with no extra vignetting.  It's amazing at what it does, but I never carry just this one to be careful to not fall into the trap of only shooting wide angle.

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