I’ve had this lens for several years but only recently decided to test it formally so that I could compare it with my 70-300 f/4-5.6 L lens. During this time, I shot thousands of travel images and it was one of my most used lenses during my trip to Bhutan. The lens’s fast autofocus, constant f/4 aperture, and light weight made it an ideal travel lens and it yielded many great pictures of traditional dancers at the Tsechu festivals.
Physically, the lens is 3″ in diameter and 6.8″ in length (Figure 2). It feels very lightweight and compact but this may be because I am subconsciously comparing this lens to its much larger 70-200 f/2.8 sibling. Unlike many other lenses, the 70-200 f/4 does not extend or contract as it is focused or the lens is zoomed. The build quality is very good and the lens is metal with a matte gray finish.
To evaluate the sharpness of the lens, I selected an architectural column of Stanford University (Figure 3) as a test subject and took photos at varying aperture and focal length. I used a Canon 5dII camera, tripod, and remote release. Image stabilization was turned off and the camera was mounted vertically with an L-bracket. The images were processed in Lightroom 3 with only white balance adjustments. Sharpening was left at the default levels (amount = 25, radius = 1, detail = 25, masking = 0) and the crops were saved in photoshop with save for web (quality = 60).
Figure 3 shows an image with the full scene and the location of 100% crops marked by the red squares. Figures 4-6 shows the pixel level detail as the focal length varies from 70mm to 200mm. In general, the 70-200 f/4 performed very well and I would summarize my findings as follows:
- Center sharpness is good at all focal lengths even when the lens is wide open at f/4.
- At 70mm and 135mm there is some softness in the image near the corner of the frame.
- The lens is very good at the long end (200mm) and is sharp to the extreme corner.
- Stopping down improves corner sharpness considerably.
|Figure 4. Performance at 70mm: pixel level detail from 100% crops.|
|Figure 5. Performance at 135mm: pixel level detail from 100% crops.|
|Figure 6. Performance at 200mm: pixel level detail from 100% crops.|
I noticed a slight amount of back focusing with the 70-200 f/4 on my Canon 5d II. This occurred when I was shooting a shore crab at Point Lobos. Figure 7 shows the full image and Figure 8 shows a crop of the crab. I had used autofocus on the close eye of the crab but the point of focus actually appears on the rear eye. Although I tried refocussing several times, I always got the same result with the focus point being just behind my target. To resolve the issue, I ended up using live view instead. Thankfully, the crab remained fairly motionless.
I’m assuming the backfocus was caused by my lens, but I haven’t tested the camera to see if it was at fault. I also have not bothered to use auto-focus micro adjustments as I don’t usually take such close range photographs with this lens.
Compared to the 70-300 f/4-5.6 L IS
- The 70-200 f/4 is a little sharper in the center but the 70-300L definitely wins in the corner. Both lenses are very good and I wouldn’t let sharpness be a factor in choosing one over the other.
- The 70-200 f/4 is lighter (1.6 to 2.3 lbs) but is also slightly longer: collapsed the 70-300 L is 5.6″ compared to 6.8″ for the 70-200.
- The 70-200 is cheaper by about $400.
- With the 70-200 f/4 you gain up to a stop in aperture but lose 100mm on the long end.
Although there is a large overlap in focal length range, I plan on keeping both my 70-200 f/4 and 70-300 L lenses. My plan is to use the 70-300 L for general travel and landscape photography. However, if I know that I’m going to be doing more people shooting or if weight is at a premium, I’ll take the 70-200 f/4.
For more information, you can also see my review of the 70-300 f/4-5.6 L lens.
- The lens comes with a rubber gasket to keep water and dust from entering in the gap where the lens is mounted to the camera body.
- This lens accepts Canon A II tripod collar but so far I haven’t felt the need for this. The Canon collar is very expensive ($140) but there are also third party collars that are significantly cheaper.
- The lens accepts 67mm filters so if you have a three lens travel kit with the 17-40mm and 24-105mm zooms (77mm filters), you’ll either need to carry an additional filter or hold it by hand.
This is a stellar lens that is sharp, light weight, and reasonably fast with a constant f/4 aperture. The lens focuses quickly and with image stabilization it makes a very nice travel lens. In my opinion, the only reason to select a different lens is if you absolutely need more range on the long end (e.g., a 70-300mm or 100-400mm) or a faster aperture (f/2.8) for action photography.
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