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Canon EF 70-300mm f/4-5.6 IS USM

70-300_isusm
Review Date: Oct 18, 2005 Recommend? yes | Price paid: Not Indicated | Rating: 9 

Pros: Excellent IS (better than expected), good quality optics for the price, good build quality (similar to EF-S 17-85mm IS USM), nice finish, inconspicuous, relatively light weight, recommended for landscape, wildlife in good light and for portraits
Cons:
No real Ring USM and FTM (Full Time Manual focus), front element rotates when focusing, variable aperture, too slow for sports or for freezing motion in low light, soft corners at long end especially wide open (however better than most consumer lenses), no weather sealing

Overview (day 1)
The Canon EF 70-300mm F/4-5.6 IS USM Lens has a useful focal length range, small size, light weight, midrange price and Image Stabilization. It is relatively small (76.5 x 142.8mm / 3.0 x 5.6" retracted) and light (630 g / 22.2 oz) for its range and fits nice a Canon 20D body. Build quality is similar with my EF-S 17-85mm F/4-5.6 IS USM -- i.e. decent: mechanically ok, nice finish, no weather sealing.

The zoom ring feels comfortable and rotates smoothly but is a bit too sticky in my opinion. The front element does not rotate when zooming; however, the front element does rotate when focusing. A switch locks at 70mm to prevent the lens from extending when not in use.

The focus ring is adequate but the front section (that extends) seems to be a bit loose when in MF mode (or at least it feels like that). Unfortunately, there is no distance scale and no real Ring USM. The Canon 70-300mm F/4-5.6 IS USM Lens does not include FTM (Full Time Manual) focusing -- you must switch to MF mode to manually focus the lens.
Focus speed is average (I expected faster AF because of the USM) but accurate in good light. In low light, especially at the long end, I noticed some focus-hunting.

The EF 70-300mm F/4-5.6 IS USM Lens uses Canon's latest generation Image Stabilizer (IS) that provides an additional 3 F-stops for handheld operation. This is definitely my favourite feature of this lens. My first indoor tests indicate that the IS is very effective: using a shutter speed of 1/40 I was able to obtain sharp photos even at the longest focal length (300 mm); I've got decent sharpness even at 1/13 @ 300 mm -- amazing !

When pressing the shutter half way down, the IS engages -- the effect is very obvious in the viewfinder -- it helps to compose the image as well. There are two IS modes: mode I (normal -- all directions) and mode II (panning -- direction of camera motion); for the moment, I've been using the first one only. The IS seems to be relatively noisy compared with my EF-S 17-85mm F/4-5.6 IS USM.

The optical quality of this lens remains to be tested. But the preliminary photos (handheld only) did not show any obvious problems in terms of sharpness and resolution. Unfortunately, it will take me a while to perform some serious tests -- maybe this weekend.

The price of this lens reflects its qualities (and defects): $736 CAD (~ $620 USD). I'm sure that at least $250 is the IS -- it is a worthy feature especially for those who want to carry less: handheld is fine most of the time in good light, but in difficult situations (i.e. in low light at the long end of the focal length) a monopod is more than enough with the IS system on. Personally, I use a Manfrotto monopod 681 + rubber head 235C. I would have paid $100 more to have Ring USM and FTM. Maybe the next generation...

Optical Quality (day 2)
I spent few hours this weekend with my new Canon EF 70-300mm IS USM telezoom. Using a standard ISO 12233 resolution chart and a tripod I tried to evaluate the quality of the optics provided by this lens by comparing it with my old EF 55-200mm USM and with my actual EF-S 17-85mm IS USM.

Test conditions:
camera used -- Canon 20D 1.6x FOVCF
sensitivity ISO 200
outdoor light, sunny day (around 3:00 pm), moderate wind
light tripod and IS turned on to compensate for wind effect
ISO 12233 resolution chart (450 x 300mm) printed on a HP inkjet plotter (~1200 dpi resolution)

Few conclusions:
Overall impression: good quality optics, better than EF 55-200, probably not L grade but not too far if you consider the price and the class of this lens.
In the range 70 to 85mm @ F8...F11 the results look similar to my EF-S 17-85mm IS USM, surprisingly sharp at the corners (hard to see real differences in terms of sharpness and geometrical distortions) -- great outdoor lens in good light conditions.
At F8 the image is sharp for almost the entire focal range -- at the long end (between 200-300mm) the image looks a bit soft without affecting the resolution -- maybe it's just the fact that I'm using a cheap tripod and IS turned on rather than a rock solid tripod, mirror lock and no IS.
Wide open the softness at the long end is present, however not annoying; corner softness is also more obvious, especially at short focal length, but nothing to worry about in real situations.
Stopped down to F16 or more this lens is soft but usable -- you can turn this into an advantage in portraits or other situations where softness is desired.
Using a 1.6x FOVCF camera, I cannot complain about vignetting or geometrical distortions (I would be curious to run some tests on a full frame camera) -- barrel distortions are minimal at 70mm and disappear around 100mm, pincushion at 300mm is also minimal. I guess that on a full frame camera the distortions may be more pronounced.
CA (Chromatic Aberration) is very well controlled -- it is much better than my EF-S 17-85mm IS USM or EF 55-200mm USM.
Canon EF 70-300mm IS USM Lens has an 8-blade circular aperture that give a very good defocused image quality (bokeh), better than EF-S 17-85mm IS USM or EF 55-200mm USM.
With a maximum magnification of .26x, Canon EF 70-300mm IS USM can be used for macro (minimum distance 1.5 m) with good results. At 300mm the depth of field is very shallow and focusing is critical AF single spot seems to work in many cases, but sometimes manual focusing and a good tripod may be critical. Here is where I miss the MTF of a real ring USM lens.

For samples and a additional information see:

http://snicolae.org/spoli/Canon/EF_70_300_IS_USM.htm

This is a work in progress, so expect changes, additions, etc.