Canon EF 300 mm f/4L IS USM
3. Build quality and image stabilization
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The build quality feels genuine excellent. We deal here with a solid, sealed barrel, made of magnesium alloys, and a metal mount. A built-in retractable lens hood is an excellent idea. We will never lose it, we don’t have to remember to screw it on; it is simply always there, waiting to be used when we need it. Under it we find a manual focus ring – big, very comfortable and allowing precise work. Even lower is situated a clear distance scale window from 1.5 meter to infinity (the range from1.5-2 meters is marked as MACRO).
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Below the distance scale we find a silver plate on which the company informs us about the parameters of the lens and the fact, that it was produced in Japan. On the left, there are stabilization switches – one to choose the mode (Mode 1/Mode 2) the second to switch it on or off.
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Next in the direction of the mount we find a place for a tripod adapter, included in box in the case of this lens model. Even lower, a bit to the left, we find a focusing mechanism switch (AF/MF) and a focus limiter (we can choose from two ranges: 1.5 meter to infinity or from 3 meters to infinity).
When it comes to the inner design we deal here with 15 elements in 11 groups. Two elements, used here, are made of low-dispersion glass UD (elements no. 2 and 5). The image stabilizer operates through the movement of the system of elements from no. 11 to no. 13. The overall picture is complemented by an eight diaphragm blades aperture which can be closed down to f/22.
The buyer gets, apart from the already mentioned tripod adapter and in-build lens hood, a tasteful case and both caps included in box.
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Stabilization
The EF 300 mm f/4L IS USM was the third Canon lens ( after an EF 75-300 mm IS and an EF 28-135 mm IS ) equipped with the image stabilization system. As it is a first generation mechanism the producer informs that its efficiency reaches just 2 EV. Of course we didn’t fail to test it in reality. For a wide spectrum of the exposure times at every one of them we took from 20 –30 photos with IS on and off. Next, we estimated the number of blurry pictures for each exposure time. The graph below shows the results of such an operation.
In this case on the x-axis we put the exposure time in EV, where 0 EV is the equivalent of 1/500 s. time. You can see clearly from that graph that the distance between two curves is 2 EV on average which result is in perfect accordance with the statements of the manufacturer.
