EF 70-300mm f/4.5-5.6 DO IS USM Review

The Canon EF 70-300mm f/4.5-5.6 DO IS USM has been available for a few months now and it's been put through it's paces by a significant number of users. Some love it, some have a little disappointed, so this review will address the question of whether this is the lens for you! Those thinking of buying the 70-300 DO lens usually consider the 75-300 IS, 100-400L IS and 70-200/4L as possible alternatives. The following table compared these lenses:

As you can see, each of these lenses has its own pros and cons.

• The 70-300DO lens is the smallest (though not quite the lightest). It has the most advanced IS system (3 stops stabilization with panning mode) and uses small filters, but it doesn't have a tripod mount and it's quite expensive.
• The 75-300 IS is the cheapest and lightest lens and also uses small filters. However it has first generation IS (2 stops stabilization and no panning mode) and though it's technically a USM lens, it's not a ring USM and it doesn't have full time manual focus. It doesn't have a tripod mount.
• The 70-300/4-5.6 IS USM has replaced the 75-300 IS. It's very similar physically, but has improved optics along with a 3rd generation IS system like that found on the DO lens. It still has a micromotor USM rather than a true ring motor USM.
• The 100-400/4.5-5.6L IS is by far the heaviest lens, almost twice the weight of the others. It's also the longest and most expensive and it's white. It does have a tripod mount and it does have 2nd generation IS (2 stops stabilization plus a panning mode).
• The 70-200/4L is 2nd cheapest, weighs about the same as the 75-300DO, but is significantly longer. It uses a medium sized filters and it can be equipped with a tripod mount (though it doesn't come with one as standard). It's white like the 100-400 and so may be more conspicuous than a black lens.

• The 75-300IS is known to be pretty good at shorter focal length settings, but gets a little weak at 300mm. It's not awful, but I think it's probably fair to say that it's the weakest of these lenses, especially at 300mm. It shows some chromatic aberration at the edges and some fall off in sharpness at the corners. AF is OK, if not spectacular.
• The 70-300IS has improved optics giving greater sharpness at 300mm plus an improved AF system giving faster focusing.
• The 100-400/4.5-5.6L IS is optically good, but again at the long end it doesn't perform as well as a prime lens like the 400/45.6L. In fact in my tests it didn't even perform as well as a 300/4L + 1.4xTC. AF is very good.
• The 70-200/4L is an excellent optical performer. Very sharp and good contrast at all focal lengths. It's the best of these lenses, but, of course, it only goes out to 200mm - and it doesn't have IS. AF is excellent.
• Now for the 70-300DO IS. Well, first the good part. AF is excellent and the IS system is very effective. The use of the DO (diffractive optic) element is very effective in suppressing chromatic aberration - in fact I haven't yet detected any in any of the DO lens shots I've seen. The disappointing part of the optical performance is also due to the use of diffractive optics though. When used wide open, bright objects may appear to be surrounded by a soft white "halo". Though this effect is greatly diminished by stopping down, it's not a fast lens to start with. Also, it's very prone to flare when used wide open and without a lens hood - much more so than other of these lenses. Again this is due to the use of a diffractive optical element. The DO makes it possible for the lens to be very short and to suppress chromatic aberration, but it does tend to make flare worse under some circumstances. Another undesirable DO effect is that there can be some "structure" in out of focus bright spots. This is similar to the "donut" shaped highlights you get with a mirror lens, though significantly less objectionable.

So who is this lens for?

If you're looking for a really, really sharp lens, which is flare resistant and optically fast, then the 70-200/4L is the one to pick. However, it's longer and more conspicuous and it doesn't have IS, so a tripod will be needed more often - plus it's only 200mm. You get the quality and the price is low, but as you can see there are potential drawbacks.

The 100-400/4.5-5.6L IS lens is probably the lens for the shooter looking for wildlife who wants a zoom rather than a prime, and doesn't care about the weight. It has both IS and a tripod mount and it goes out to 400mm, but it's heavy and expensive.

The 75-300/4-5.6IS is a compromise. It's the cheapest of the 4 lenses, it's fairly inconspicuous, fairly small, fairly light. The AF is slower than the others, the IS system not so advanced and it falls off optically at 300mm, but it's cheap and it does go out to 300mm. It sometimes gets a bad rap, but I actually own one - so it can't be (and isn't) all that bad!

The new 70-300/4-5.6IS is an improvement over the 75-300/4-5.6IS in terms of optical quality and AF speed. It still lacks full time manual focus and the front element rotates during focusing. However it's about 1/2 the cost of the DO lens, so it's a strong contender for those who don't mind that it's a little larger than the DO lens and that it doesn't have a ring USM motor.

It seems that those who realize what the 70-300DO lens is, and what applications it's aimed at, generally like it and are happy with it. Those who think it might be a small, light lens with the optical performance of an "L" series prime will be the ones who are disappointed. It's not. There is no such lens I'm afraid.

Finally, this is what Canon have to say about the 70-300DO IS USM:

The EF 70-300mm f/4.5-5.6 DO IS USM lens provides up to three stops of effective shake reduction capability, equivalent to shooting handheld at 1/30 with the stability found on conventional lenses at 1/250. The lens is also equipped with a switch that offers a choice of general stabilization (Mode 1) and deliberate panning (Mode 2). The IS system remains functional when the lens is used on a solid tripod, although handheld usage is the norm thanks to its compact size. The lens' new image stabilizer unit, new compact, shake detection gyro sensors for smoother control of IS optics, and new compact zoom locking mechanism (that locks the lens at its smallest 70mm setting and prevents lens "creeping" while camera is carried on a neck strap) also contributes to the lens' smaller, more comfortable size.

Additionally, Canon has improved the Autofocus speed compared with the previous (conventional) 75-300mm IS design lens by providing a larger, ring type Ultrasonic Motor that provides more power and torque than the smaller Micro USM and by designing a new rear-group AF system that moves much lighter and smaller lens elements at the rear of the lens for focus, keeping the larger, front elements from rotating during AF or zoom operation. Here again, enhanced AF CPU and electronics speed the AF data communication with the camera body.

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