April 6, 2014
Review originally written in April 2014, updated March 2017.
This is just an incredible lens that, provided you can afford it, will deliver in spectacular fashion.
My first standard range zoom for full frame was the 24-105 f/4L IS. I found myself using it only when I absolutely had to. Generally, the photographs taken with it lacked sharpness, contrast and depth of color. For any situation that mattered, I ended up using primes - the 35L, 35 f/2 IS, 135L, or the 50/1.4.
All this changed when I rented this lens in December 2013 for a trip to Utah. Looking at the photographs after my trip, I was stunned by the sharpness and color rendition in the landscapes captured with this lens. I could not see any meaningful difference between the shots taken with this lens and those with the 135L or the 35 f/2 IS which I had also taken with me. Here at last was a standard range lens that offered the convenience of a zoom with little or no sacrifice in image quality compared to a prime. Very quickly, my 24-105 and a couple other lenses went on sale to finance the purchase of this lens.
Since my purchase, I have used this lens for portraits, low light events, and landscapes, and it has never failed to deliver. Focusing, even at f/2.8 and in AI Servo mode is quick, accurate, and decisive. Stopped down when used for landscape photography, it shows excellent corner to corner sharpness - for a recent project, I shot identical photographs with this and the 35mm f/2 IS and could not, even at 100% magnification, see any difference in sharpness, color, and contrast between the two. The lower weight compared to the old version, new hood design and center pinch cap are all very nice features which add to the pleasure of using this lens. I continue to use the 35mm when I need the extra stop or IS - such as for hand held late evening street shots - or just some thing small and light; and of course nothing I have shot with can approach the pure magic of portraits taken with the 135L. The bulk of the time though, this and the 70-200 f/2.8L IS II are the lenses I reach for. Both are lenses that, apart from maximum aperture, can mix it up with the best primes I have shot with. Both focus faster and more accurately than primes I've used (but see addendum).
If, like me, you do not make money from photography, it is rational to ask whether a lens like this is worth it, and I will offer this perspective. This lens, much like its equally accomplished big brother, ranks among a select few that you can mount on your camera and walk into practically any situation with complete confidence that you will return with great pictures. If you love photography as I do, if getting the shot matters to you, that is worth the price of purchase.
Image Notes: The Milky Way panorama arcing over Glacier Point, the Fall color photograph, and the wide field of the constellation of Orion were taken with a 5D Mark IV. The Orion photograph is a stack of approximately 20 minutes worth of 45 second subs with tracking using an iOptron SkyTracker Pro.The photograph of Mt. Rainier and Seattle from the Bainbridge Ferry were taken with a 5D Mark III. The excellent corner sharpness makes this lens a great choice for landscape photography; the fast aperture makes it a good choice for astrophotography, although faster primes will yield better results.
Addendum: The one lens in this range I've used recently that does out resolve this is the new 35mm f/1.4L II. That wonderfully sharp lens resolves visibly more detail in the landscape photos I've taken with my 5D Mark IV and focuses just as quickly and accurately as this zoom. If you're looking for absolute sharpness, and can make do with a 35mm focal length, that is the lens to use. For me, this 24-70 is plenty sharp, particularly at its wide end where I use it a lot, and I value the versatility more than the increase in sharpness and two stop advantage the new 35mm has. For specific applications such as astrophotography, this calculus will change, but for me, those needs are infrequent enough to where renting the 35mm when I need it makes more sense. Your needs could well lead you to a different choice.
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