CANON EF-S 17-85mm IS USM: Digital SLRs Only!

Most affordable digital SLR cameras like the Digital Rebel or EOS 20D sport a smaller image sensor (compared to 35mm film) and that translates into an 'unused' area that's covered by 35mm lenses. By optimizing the lens toward the smaller area, the lens itself can be made more compact. The only negative is the smaller sensor also affects the field of view and with it especially the wide-angle. The EF 28-135mm IS USM lens from Canon is an established lens in the 35mm world for many years, but when applying the 1.6x factor of the Digital Rebel or EOS 20D it suddenly becomes a 45-216mm lens and practically all the wide-angle has been eliminated.

The new Canon EF-S 17-85mm IS USM f4/5.6 lens is basically an (optimized) adaptation of the older 28-135mm lens, which also happens to be the 35mm equivalent of the 17-85mm. Digital photography is a little bit more demanding regarding the anti-reflection coating used in the lens since the sensor reflects more light than film and may cause ghosting. The new 17-85mm lens has been revised to meet this demand. Another side effect of the revision is the 5% reduced length (insignificant) and the 12% reduced weight (significant) compared to the 35mm cousin.


EF-S 18-55mm vs. EF-S 17-85mm

Speaking strictly digital (EF-S mount), the EF-S 17-85mm lens is only the second one published by Canon. The first lens was the EF-S 18-55mm f4/5.6 which originally was only available in a kit with the Digital Rebel. A cheap lens ($99 difference for the kit) but not bad at all. Small, lightweight and good optical quality earned this lens respect, but mostly in the amateur arena. Shortcomings included rotating filter mount, limited zoom range, and the somewhat flimsy construction.

Due to the restrictive EF-S mount, the EF-S 17-85mm IS USM only fits the EOS 20D and the Digital Rebel (300D / 350D). At first glance the difference in physical size is the most obvious. The next impression is that this lens is significantly heavier (450g / 1 pound) than the EF-S 18-55mm. A closer examination reveals that the weight also comes from a sturdier case. Here the bad news if you're using Canon's semi-hard case EH-16L: The EF-S 17-85mm lens does not fit in it anymore. Also, filters for the 67mm front of the 17-85mm lens are usually more expensive than the smaller 58mm filters for the EF-S 18-55mm lens.

The main argument to spend the $540 (best offer) for the EF-S 17-85mm lens, however, consists of the Image Stabilizer (see below) and the non-rotation filter mount. The latter is significant for rotation sensitive filters like a circular polarizer, where you would not want the effect to change during focusing. Another positive side effect of the internal focus is the constant length of the lens during focusing. This is especially important for close-up filter lenses with extremely low depth of field. The lens also shows to be stable and does't creep out of zoom or focus when pointing down. (A major problem with the otherwise great EF 24-85mm f3.5/4.5 USM lens that came with the EOS IX.)

The one positive thing about the older EF-S 18-55mm lens is the better Macro capability due to the closer focusing distance. Using the EF12-II extension, the magnification factor of 0.68 maximum exceeds the 0.41 of the EF-S 17-85 by far. In other words, when doing close-ups, the older lens will yield almost twice the magnification. For more information on the EF12-II extension ring please use this link.

Most obvious but still worth consideration is the extended zoom range and 17-85mm covers everyday tasks much better than the somewhat short EF-S 18-55mm. (The difference between 17mm and 18mm is insignificant.)


ULTRASONIC MOTOR

Ever gotten into a situation where your lens spoiled the moment because of the noise the focusing drive makes? That's where the ring-type ultrasonic motor helps out and performs this task extremely quietly. In fact, with some background noise, it's practically not noticable.

Autofocus (AF) feels faster than with traditional drives and one positive effect is that using the manual focus ring during autofocus does not harm the drive and your investment is safe in the long-run.

The ultrasonic motor makes a big difference and especially in situations where every noise is unwanted (just think of climax of a wedding ceremony ;-). People around you will appreciate it and you will not have to be worried about it.

With the EOS 20D the noise becomes a moot point due to the loud flip-up mirror, but the fast AF system in the EF-S 17-85mm lens really shines.

Further, cameras supporting E-TTL II (like the EOS 20D) require an USM drive for distance feedback. Hence in order to use the enhanced flash in the Rebel XT or EOS 20D, this lens will even help your flash pictures.


IMAGE STABILIZATION

First let's clarify that IS (Image Stabilization) compensates motion of the camera only (mostly for hand-held shooting) and does not affect moving objects in any way. It extends the usability of this lens for critical low light conditions.

There is no significant benefit from IS when enough light is available to allow shutter speeds faster than the reciprocal of the used focal length. (Rule of thumb: Shutter Speed = 1 / Focal Length) For instance, using a 85mm lens, the shutter speed should be 1/85 second or faster.

Image stabilization helps to obtain sharp images at slower shutter speeds and the EF-S 17-85mm IS USM lens is rated to be effective for up to 3 stops beyond a normal lens. Using the example above, the 85mm focal length now allows a slower shutter speed of up to 1/10 second with similar results as far as camera motion induced blur. That's significant and worth the money!

Canon's approach to take the 'jitter' out of hand-held shots at slow shutter speeds is an expensive one due to the integration it into the lens rather than the camera body (as Minolta recently introduced the Maxxum 7D). Hence every lens needs its own system and you are paying for it.

Beyond making money for the company, Canon's approach sure has merit from 2 perspectives. First, it's compatible to traditional film cameras, but that doesn't really apply anymore as the EF-S mount would not be compatible anyway. Second, physical nature of the light path translates minimal movement of the lens into greater movement at the picture plane. A lens subassembly is moved by electromagnetic drives to counteract the motion measured by the 2 gyros (pitch & yaw). Tiny motion in the lens is enough to compensate for significant movement of the camera -- at least in theory. Or in other words, the Minolta system has to be more vigorous in order to achieve the same efficiency as an in-lens solution (as shown by Canon and Nikon). Nevertheless, both Minolta and Canon do quite well with improvements by about 3 stops.

Image Stabilization works well and can even be observed without taking a picture, simply by comparing the picture through the lens with one eye and the natural view with the other eye. The stabilized image follows the camera movement and creates a slightly strange experience where it seems to be frozen when moving the camera a little bit.

Due to the tuned sensitivity of the gyros, IS is most effective for small but 'fast' vibration, pretty much the kind that occurs when holding the camera causing unwanted blur. Smooth and slow motion remains largely uncompensated. Further, be advised that it's best to turn IS off on tripods as the drive might 'humm' while the camera is stationary and effectively degrade your picture slightly. (Shots on a tripod are sharper without IS.)


SUMMARY

Given that this lens alone costs almost as much as the street price for a Digital Rebel body, I had high expectations. Almost every single one of them was met or exceeded (extended zoom range, sharper images, quieter operation, resilient filter mount). That sure helped to cope with the expense as it was justified by the results. Hey and think of the more professional looks of this lens compared to the toy character of the (not that bad) EF-S 18-55mm. Invent other reasons for upgrading as you see fit.

A little bit short of expectations fell the close-up capability (macro). But beyond that I am having trouble to find other negatives. (Hard-core professionals might find more than that, like the slightly soft rendering typical for a midrange zoom.) Sure, power consumption goes up, but I have yet to find out that it really matters in my applications. Well, I will need a set of 67mm wide-angle filters (after I just got a set for 58mm) and that adds to the cost, but that's hardly the fault of this lens.

While speed is relative and IS compensates well for the f4 to f5.6 maximum aperture, portrait photography most likely require an additional (faster) lens for more shallow depth of focus -- to better isolate object from background especially when they're close. For those cases you may look into the 3rd EF-S lens to be released in April 2005: the EF-S 60mm f2.8 USM. It should fix the remaining issues of the 17-85mm IS lens, but will set you back another $400. (Not counting additional 52mm filters.) However, the 1:1 macro capability and improved picture sharpness may be worth it. To take things even further, check out the (pricey) EF 70-300mm f4.5-f5.6 IS DO USM for excellent long-distance performance.

Note: The f4 maximum aperture is not enough to enable the precision focus in the EOS 20D which requires a f2.8 or better to be enabled.

Overall, the EF-S 17-85mm IS USM f4/5.6 is a great multipurpose lens for the upcoming years and due to it's performance take the place of my primary lens. Right now, I can only recommend this lens. Of course keep in mind that the added expense should fit your needs rather than wants. ;-)

© 2004, theuerkorn