With the Canon EF 16-35mm f/4L IS USM Lens
and Canon EF-S 10-18mm f/4.5-5.6 IS STM Lens
reviews recently happening back to back for me, a question that I had in my mind for quite some time became highlighted. That question was: "What is the difference between the image stabilization systems found in Canon's EF-S STM and other budget-priced lenses and those found in higher grade lenses including those in the L series?
Perhaps the question was most-driven by the "feel" of a large price differential between these image stabilization systems. Determining exactly how much IS adds to the price tag is not easy since there are not many Canon lens focal lengths or focal length ranges available in the same max aperture with image stabilization being an optional feature. Three examples are the 70-200 f/4, 70-200 f/2.8 and 100mm f/2.8 macro lenses. In all three of these instances, the IS version is considerably more expensive, with the $450-$1,050 difference being more than the price of most STM lenses. In all fairness, the IS version of the three just-mentioned lens siblings is a considerably-newer model and newer lenses typically have better technology and are always more expensive. But, it still "feels" like the IS system in the higher grade lenses is more expensive than the IS system in the lower-priced STM (and similar) lenses. This of course drives my wonder about what the difference between IS systems is.
So, I asked Canon. My direct question was "Can you explain the differences between the image stabilization system implemented in an inexpensive lens (such as the EF-S 10-18 STM) compared to that implemented in a high end pro lens (such as the EF 16-35 f/4 L)?" Following is the information that Canon USA and Canon Inc. were willing to disclose: EF-S 10-18mm f/4.5-5.6 IS STM
EF 16-35mm f/4L IS USM
- The compensation optics lens barrel is suspended by 3 springs that hold it in place in the center. This makes it possible to eliminate the compensation optics retaining mechanism in this IS unit.
- The drive actuator for the compensation optics lens barrel is constructed using the same permanent magnets and coils used in existing IS units.
- Making use of the technology that has been garnered in existing L-series IS lenses, such as a stepping motor for the compensation optics barrel lock mechanism, this lens is able to achieve both high-performance image stabilization and compactness of design.
- The moving parts in the compensation optics barrel have been improved from sliding friction to rolling friction by way of combining rolling balls and V-grooves in an ultra-minimum-friction structure. This design improves IS performance while reducing power consumption.
In addition, the following table was provided to me:
|Specification||EF-S 10-18mm f/4.5-5.6 IS STM||EF 16-35mm f/4L IS USM|
|IS Mechanism||Parallel-moving corrective optics (Single element.) IS unit is based on the one used in the EF-S 18-55mm f/3.5-5.6 IS II.||Parallel-moving corrective optics (Group of 4 elements.) IS unit is newly designed especially for this lens.|
|Shake Detection||Via gyro sensors (1 sensor each for yaw and pitch)|
|IS Activation||Turned on with the IS switch and activated by pressing the shutter button halfway (SW-1)|
|Centering/Lock when IS is Off||When the IS is Off, image stabilization optics are locked in place with a spring suspension mechanism rather than a center lock mechanism.||When the IS is Off, the image-stabilizing lens group is centered and locked in position. |
|Mode Selection||None (Automatic switching between normal shooting mode and panning mode is determined by gyro sensor signal.)|
|Vibration Reduction (Based on CIPA Standards)||Equivalent to 4 shutter speed steps faster (Focal length 18mm, 35mm equivalent: 29mm, using EOS 7D)||Equivalent to 4 shutter speed steps faster (Focal length 35mm, using EOS-1D X)|
|Dynamic IS/Hybrid IS||None|
While not completely revealing, the above information does show some of the IS design differences between these lens classes.