Canon EF 17-40mm f/4L USM Ultra Wide Angle Zoom Lens for Canon SLR Cameras: Customer Reviews & Product Details

I'm using the lens on a XSi. I'm still reviewing, but my initial thoughts are the focus isn't quite as sharp as it could be? Very low distortion, CA, etc. Sometimes I just can't figure out why some of my images are a tiny bit out of focus. I'm an amateur photographer, so it might be bad hand holding or some other beginner mistake. But, since I bought it, it's mostly stayed on my camera.
This isn't a good indoor lens without a flash. The f4.0 is just a little too slow unless it's bright indoor light.
I plan to shoot more with the tripod to push it all the way to my limits. Then I'll either come back and bump up my review, or bump it down. This is a pricey lens.

I had been using the 28-135 IS for some time until I decided to break down and buy this lens. And being a college student, it was the obvious choice over the $1000-more-expensive 16-35 f/2.8L. But, about once a week I find myself in a situation where I think "Hmm, that extra stop would be nice about now." And I imagine that a lot of people find themselves in this pickle. So here's what you need to know and to think about:

1) Ask yourself, what do you shoot? Are you a budding photojournalist? A band photographer? A proud father?
To everyone except those hoping to do photojournalism or weddings, I would say, this lens is the obvious choice. It is light, but the build quality is very solid. The focus and zoom are so well-damped, it just feels like you are holding a quality lens. And you are. It is sharp (for a wide zoom, anyway) and solid.
To those doing weddings or PhoJo: Wait the extra 2 months, save more, and buy the 16-35 f/2.8L II. I shot for a newspaper for the last year, and while I was always able to make this lens work, it put me in the situation where I "had to make it work," and that is not something you want to do to yourself. You want to not have to worry about your gear, and I frequently needed to, as I, oddly, would find myself in that situation where I needed that extra stop quite frequently. When I bought it, I thought "How often will I need that extra stop?" Now I wish I had saved up for the extra stop of light. When you are doing weddings or phojo, the only thing that matters is your photos. Don't put them at risk by having to shoot at 1/30 when you could be shooting at 1/60. Nothing in photoshop cures motion blur.

So, if you don't shoot lowlight, or don't care about a little less bokeh, there is no reason to buy the 16-35. This lens is lighter and just as sharp. THE ONLY THING that you get out of the 16-35 is the extra millimeter and the extra stop. But, if you are someone who might need that extra stop once a week, don't buy the 17-40 just to have to buy the 16-35 later.

I picked this over the 17-55 f/2.8 IS because of its lower price and L-series construction. Theses lenses are intended for different uses, though. I don't need a lens that fast.

Never used the 17-55 f/2.8 IS, but both versions of the 18-55 (II, the XT & XTi kit lens; and IS, the XS, XSi, etc kit lens) and this lens is a beast in comparison to those. Amazingly solid construction, fixed-aperture, sealing, fast USM (which makes no big differences on Wide Angle lenses, but in noise does) and FTM are pros on this lens. I will not review optics, you can find websites on that much more detailed than here.

On the other side I must say the hood included doesn't seem to be very effective, because it's so shallow. It makes polarizing easier - eyes on the viewfinder, one hand on the grip/shutter button and the other rotating the polarizer. No tripods or snapping hoods on and off.

I love this lens and would defintely buy this again.

If you're shooting an APS-C Canon and you've decided that you only want EF full-frame lenses for future use on a full frame camera, the 17-40 is a must-have. The focal range on the cropped sensor is 27 to 64mm which covers a large range for the majority of shots most people are likely to take. I've found this lens is perfect for social gatherings and essential for group shots. The size and weight is perfect on the 7D, making this my favorite lens for handling (compared to the 24-70 f2.8L and the 70-200 f4L). The build quality is superb. The focus and zoom rings couldn't be smoother and AF is fast. While this is a sealed lens, I hear that it's not fully sealed until a filter is fitted. With one in place, the zoom extension is completely internal, so there's no change in length when zooming from wide to the long end.

This lens is a fixed f4. If you buy the lens with the understanding it is not an f2.8 and will not get you the lower ISO and/or faster shutter speed of an f2.8, the lens does very well in most shooting situations. On the 7D it's even better with the excellent high-ISO performance of that camera (I can shoot at ISO 3200 to 5000 without much concern). While it is reasonably sharp at f4 across the focal range, it is not as sharp as when stopped down to f5.6. Also, boarder sharpness falls-off a bit wide open and close to 40mm. However, these are not big issues. Contrast and color with this lens is excellent. My only caution from experience is to be careful when adjusting the point-of-focus to depth-of-field balance with the micro AF adjust on the camera (if you have that feature). What may appear to be a correct adjustment with a focus scale sheet that uses the center of the field, may end up causing excessive edge softness of your images due to the edge of the frame starting to fall out of the depth of field. I believe this may be due to the field curvature characteristic of a wide angle lens where the focal plane is not equidistant from the camera lens but slightly curved. I spent some time setting the correct AF micro adjustment by photographing a large bulletin board with very small lettering and symbols across both dimensions while making sure the camera was pointed square to the center so that all corners were equal distance from the camera. Once you have this dialed-in, you can test the center-to-corner sharpness of your lens at different focal lengths and apertures and determine whether you may have any sharpness issues with your copy. Initially I thought I had a bad lens copy that was soft and de-centered, but after getting this procedure right, the lens proved to be sharp.

While there are other excellent options such as the Canon 17-55 EF-S f2.8 lens, this one is full-frame compatible, it's weather sealed, it has superior build quality, it's an L lens with that unmistakable red ring at the end, and it's the next greatest lens bargain second to the 70-200 f4L. While the hood may look odd, remember that it was intended for a full-frame camera where this lens would be a true 17-40mm - making a shallow hood necessary.

I've been using this lens for a couple of months now and I must say that I'm very pleased. I use a rebel xti (1.6 crop), so this is a medium wide lens for me.

pros:
* good close up lens for indoor photos if you have good light
* enough angle to photo someone from close up
* light and feels balanced

cons:
* it's an f/4 at best, so without a flash, it's hard to get good shots in low light.
* the front element is convex - not a con per se, but you'll want a uv filter to protect it

I've shot in a house party with medium - dim lighting, and without a flash (which is my preferred usage), it requires some work with Pshop to get the pictures to come out well. If I could get an f/2 of thi it'd be great, but heavy and expensive.