Although the Canon EF 24-105mm f/3.5-5 IS STM lens is a lower-end option than its line of L lenses, which are frequently paired with full frame Canon cameras, it's still a high-quality zoom. The EF 24-70mm f/2.8L I ($1,899.00 on Amazon) doesn't have the fixed-wide aperture that the pro lens is known for. However, it does include image stabilization and better zoom capabilities.
It also has a compact size considering its coverage. Although it is a good choice for photographers who are looking for an affordable, lighter lens to use with a full frame body, there will be distortion in the zoom range.
The 24-105mm (Adorama: $599.00) measures 4.1 by 3.3 inches (HD), weighs about 1.2 pounds, and uses 77mm from filters. The 24-105mm is noticeably lighter than its predecessor, the EF-24105mm f/4L USM ($1,149), zoom. It measures 4.2x3.2 inches and 1.5lbs.
However, it does not have the same weatherproofing as the L-series lens. There are just a few control toggles on the lens—a lock to keep the lens set at 24mm when it's stowed, and switches to change the focus mode and turn the image stabilization system on or off. The lens hood can be bought separately at $40.
The zoom lens can focus to 1.3 feet, so you can get very close to your subjects even if the zoom is extended all the way. It occupies most of the barrel. There are markings for 25mm, 35mm and 50mm respectively. The focus ring sits ahead of it; like other lenses with STM motors it uses a focus by wire system—turning the focus ring when the lens is set to MF mode activates the motor rather than mechanically moving lens elements. This is a problem if you want some physical feedback while manually focusing; L series zooms within this range use a mechanical manual focus system.
Near silent focus is what the STM motor offers that USM motors lack, particularly during Live View. This is a great advantage if your main focus device is the STM motor. Canon doesn't currently have a full-frame body with that technology, but even when you pair the 24-105mm with the EOS 6D you get Live View focus that's quick, smooth, and silent—it's just not as fast as a Dual Pixel AF camera like the 70D or 7D Mark II ($598.95 at Amazon).
Imatest was used to test the performance of the lens when it was paired with the full-frame EOS6D (20-megapixel) ($1,699.00 Amazon). Sharpness was never an issue. It scored better than 1,800 lines per image height, which is what we want in photos at each tested focal length and aperture. It manages 2,358 lines at 24mm f/3.5, and it performs well throughout the frame.
The edges are slightly behind the center of the frame but still display 1,793 lines. There is also a decrease in the illumination around the perimeter. Although the overall score (2.576 lines) and edges (2.009 lines), only marginally improves at f/4, they are noticeably better at f/5.6. At f/5.6, the vignette you can see at the edges of both f/3.5 images and f/4 images are barely visible. The 24mm f/8 lens has the best results, showing 2,641 lines in the frame and edges close to 2,400 lines.
The maximum aperture drops to f/5 by the time that you reach 50mm. This lens is a good choice, with 2,460 lines per inch and edges at the top of 2,100 lines. The lens shows a slight improvement at F/5.6 and the peak at F/8 with a center weighted score 2,606 lines.
At 105mm, the maximum aperture is only f/5.6. However, sharpness does not suffer. The lens manages 2,497 lines in a center-weighted test. It has sharp edges just like at 50mm. The score is slightly improved by reducing the aperture to f/8; there are 2,540 lines. At 50mm and 105mm, peripheral illumination isn't a major problem.
All zooms have distortion. The lens exhibits 1.5 percent barrel distortion at 24mm. This makes straight lines look like they have an outward bulge. The lens displays 1 percent pincushion distortion at 50mm and 1.8% at 105mm. Both are visible in the field.
The 6D is not compatible with Canon's in-camera correction of distortion when you shoot JPGs. You can adjust the profile of images taken with this lens in Raw format using Adobe Photoshop Lightroom. This compensates for distortion and peripheral illumination loss.
The full-frame zoom lenses are often expensive. However, the Canon EF 24-105mm f/3.5-5.6 IS STM bucks this trend and offers sharpness without compromising price. The zoom range has noticeable distortion, which can be easily corrected with some editing.
However, it is difficult to create detail with fuzzy lenses because of the limitations of software. It's an excellent option for Canon full-frame shooters and works well in combination with the 6D entry-level body. L lenses are more expensive for serious photographers.