The Canon EF 24-105 f/4L IS USM is a professional-grade zoom lens with image stabilization, a useful focal length range and constant f/4 max aperture. It's classified as an L-series lens, meaning that it is manufactured for top image and build quality, and is not cheap.
Focal Length Range
The EF 24-105 f/4L is a general purpose zoom lens. Its range of focal lengths is very useful, going from wide angle at 24mm to telephoto at 105mm. You can shoot sweeping landscapes with the short end, then zoom in close for portraits, detail shots and the like.
Photographers whose cameras have APS-C sensors will not see a wide field of view on the 24mm end of this lens due to their cameras' crop factor. This includes the Digital Rebel series, prosumer series (30D/40D/50D etc…), and the 7D. If you have one of these cameras and are looking for a wide angle field of view, you'll need to look at lenses around 20mm or less.
Aside from its effects on the wide angle field of view, a crop factor will give you a lot more reach on the 105mm telephoto end of this lens which most people usually appreciate.
A DSLR with a crop factor has a sensor smaller than traditional 35mm film. This has the effect of "cropping out" a smaller area of the scene, hence the name. Crop factors don't change focal length or make this any less of a lens, but they do change your field of view and so you should be aware of their effects.
Wide Angle Distortion
The 24-105 suffers from very noticeable distortion at wide angles. Lines will curve and bulge out -- depending on your position and angle on the subject, the effects range from very slight to pronounced.
Notice how the columns of the building bulge out like a barrel. This effect is sometimes apparent at the short end of this lens and disappears as you zoom in.
The Image Stabilization of the EF 24-105 f/4L IS USM is extremely useful. The IS enables 3 extra stops before you see blur from hand movement. I've made extensive use of this feature in dark environments and can attest to its effectiveness.
Take a look at the details in this image. The lines on the barrel and in the writing are all sharp, and yet this photo was shot hand-held at 1/6 sec. Besides hand-holding at slower shutter speeds, IS is also the gateway to more depth of field in dark situations, and using lower ISO ratings to improve image quality and reduce noise.
Keep in mind that although IS reduces blur resulting from hand movement, it cannot reduce motion blur. In order to freeze moving subjects you must use a fast shutter speed.
Constant f/4 Max Aperture
The EF 24-105 f/4L IS USM features a constant maximum aperture of f/4. This is a welcome advantage over kit lenses and consumer zooms which usually have a variable maximum aperture in the f/3.5-5.6 range.
In a kit lens, the maximum diameter of the opening through which light passes shrinks as you zoom in. This affects your exposure -- you need a slower shutter speed or higher ISO in order to get a telephoto shot than you do when shooting the same subject zoomed out to a wide angle.
I cannot stand having to re-think my exposure settings as I change focal lengths, and so lenses like the 24-105 with a constant maximum aperture are a welcome upgrade. The 24-105 can shoot at f/4 at 24mm, and it still shoots at f/4 when zoomed in to 105mm. A kit lens might have f/3.5, or even f/2.8 at the short end, but will likely go to f/4.5 or 5.6 when zoomed in.
An f/4 lens usually isn't associated with diffuse, out-of-focus backgrounds ("bokeh"), however the telephoto capabilities of this lens make subject isolation a little more possible. Get close to your subject, zoom in to 105mm, shoot wide open at f/4, put some distance between the subject and the background and you'll get some nicely blurred out-of-focus backgrounds.
The EF 24-105mm f/4L IS USM has very good image quality. It is respectably sharp starting at f/4, gets nice colors and contrast. Its wide angle distortion can be frustrating, but is also fixable if you're willing to spend a few seconds doing perspective correction in Photoshop.
Like other L lenses, the 24-105 is built tough. The lens is weather sealed (requires a filter on the front element to complete sealing) and the barrel is rugged. How rugged? I dropped my 24-105 from chest height onto asphalt while in Europe. It hit the ground, took a bounce and rolled to my feat. After making sure the mount was not damaged I took it back to the hotel, put it on my camera, did a few test shots and discovered the IS, auto focusing and other features were still in perfect working order. I continued using the lens throughout the remainder of the trip. The only evidence of the incident are a few nicks on the barrel. I'd call that impressive.
Please do not try this at home.
The 24-105 is an extremely versatile zoom lens. The image stabilization makes low light photography much more accessible to photographers without top-of-the-line cameras, and the focal length range leaves you ready for almost any situation. This is an excellent travel lens -- I've gone on many trips with the 24-105 as my only gear.
I cannot end this review without mentioning the Canon EF 24-70 f/2.8L. If you spend any amount of time on photography social networking sites and message boards, you know that the two of these are compared constantly. Many Canon photographers looking to upgrade their kit lens and move into "L territory" often consider these two similar lenses. The 24-70 lacks IS and does not zoom as far as the 24-105, but it does have a larger maximum aperture of f/2.8.
Both the 24-70 and 24-105 are excellent lenses, and your decision between the two depends entirely upon your shooting style. Photographers looking for an all-around solution, a lens to put on the camera and leave there, would probably prefer the 24-105. On the other hand, prime lens shooters may prefer the optical quality of the 24-70.
I own both of these lenses. The 24-105 got constant use for a number of years, but I've recently switched to the 24-70 because I feel its image quality is closer to my prime lenses, which are what I prefer the most. In my opinion the 24-70 gets better color and contrast than the 24-105. The 24-70's f/2.8 also makes it more possible to capture moving subjects, which suits a photojournalistic style.
With all that said, the 24-105mm f/4L IS is one of the most versatile professional quality lenses you can get from Canon, and if I had to choose just one piece of equipment to travel with, it would be the 24-105.
Where to to Buy the EF 24-105 f/4L IS
- Canon EF 24-105mm f/4 L IS USM at B&H
- Canon EF 24-105mm f/4 L IS USM at Adorama
- Canon EF 24-105mm f/4 L IS USM at Amazon.com
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