Canon EF 70-300mm f/4.5-5.6 USM DO IS - Review / Lab Test Report
Lens Reviews - Canon EOS (APS-C)
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Review by Klaus Schroiff, published February 2006


The Canon EF 70-300mm f/4.5-5.6 USM DO IS is a very special lens - not so much regarding its naked specifications but because of its DO design. DO refers to a multi-layer Diffractive Optical element that bends light steeper than conventional (refractive) elements thus allowing a shorter design in conjunction with less color fringing and less spherical aberrations. It is the second Canon EF lens to use this technology with the first one being the Canon EF 400mm f/4 USM DO IS. The DO lenses form a new group within the Canon lens hierarchy distinguishable via a green ring at the lens front rather than the red one used for L class lenses.

The DO element is also visually recognizable (unlike UD or CaF2 elements). In the image below you may notice the concentric circles in the glass.

On APS-C DSLRs the field of view of the EF 70-300mm DO is equivalent to 112-480mm. It's a full frame lens and as such compatible to all EOS cameras out there.

One key selling factor for this lens is naturally the Image Stabilizer (IS). Camera motion is detected by 2 gyro sensors which measure the angle and speed of the shake. This information is used to shift a lens group off the optical axis (basically a forced decentering) to counteract this motion. The result is a significant improvement of handholdibility (3 f-stops equivalent). The IS in the EF 70-300mm DO offers 2 different modes:

  • mode (1) for static scenes where the IS corrects shake both vertically as well as horizontally
  • mode (2) for action photography (object tracking) where only vertical shake is corrected

    Please note that IS has its limitations - you may be able to shoot at much slower shutter speeds but slow shutter speeds come at risk of motion blurr (of fast moving objects in your scene). That said IS is immensely useful in many field situations.

    As you can see above the lens has a rather conventional mechanical design. It extends towards the long end of the zoom range. Size-wise it is fat lens being very short (28% shorter according to Canon) for such a tele photo lens but with a very large lens diameter. At 720g it isn't especially light weight but the pretty good build quality, located somewhere between Canon consumer grade and L class lenses, takes its toll here. As a negative side effect of the additional weight the zoom mechanism has a rather strong tendency to creep when tilting the lens up- or downwards. Canon has integrated a zoom locking switch but unfortunately this works in the 70mm position only.

    Thanks to a ring-type USM drive the AF speed is very fast and basically silent. FTM (full-time manual focusing) is always possible in one-shot AF mode. Unlike most consumer grade lenses the EF 70-300mm f/4.5-5.6 DO USM IS has a non-rotating front element.

    Interestingly the primary competitor for the lens is also made by Canon - the recently introduced EF 70-300mm f/4-5.6 USM IS which follows a more conventional design approach. Here's a comparison of the naked specifications:

    LENS EF 70-300mm f/4.5-5.6
    EF 70-300mm f/4-5.6
    USM IS
    design: 18 elements in 12 groups with 1x DO element 15 elements in 10 groups with 1x UD element
    size: 82x100mm 77x143mm
    weight: 720g 630
    image stabilizer efficiency: 3 f-stops, 2 modes 3 f-stops, 2 modes
    aperture blades: 6 8
    min. focus: 1.4m 1.5m
    filter size: 58mm 58mm
    AF motor ring-type USM with FTM and non-rotating front element micro-USM, no FTM, rotating front element
    approx price tag: 1100 EUR/US$ 550 EUR/US$

    As you may notice most of the specs are fairly similar. It'll be interesting to see whether the DO lens is really worth the double price tag ...

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