Let’s start this chapter with a chart comparing the properties of the tested lens, those of its predecessor and those of other models with similar parameters. As you see in the new device the number of optical elements is higher than the number of elements of the older lens; you can also notice the increase in weight. The minimum focusing distance is better and there are more diaphragm blades in the aperture.
Another chart is also worth consulting. We compare there four lenses with a similar entrance pupils. The DO technology advantage is clear – the EF 400 mm f/4 DO IS II USM is physically the lightest lens of them all and the differences are distinct.
In the photo below the Canon 400 DO II is positioned between the Canon EF 100 mm f/2.8L IS USM Macro and the Canon EF 35 mm f/2 IS USM.
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The tested lens starts with a metal mount and contacts. If you look inside you can find the first part of the lens, positioned about 23 mm deep – a removable filter, 52 mm in diameter, which is added to the accessory kit. When you remove the filter you see the first proper lens element situated 32 millimetres deep. It doesn’t move; the area close to the element is black and very well matted.
Passing to the proper barrel of the lens you see the first casing part, as wide as 27 mm. On the top it has a filter mount for 52 mm filters mentioned above and a focusing mechanism mode switch on the left (AF- autofocus, PF – power focus, MF – manual focus). It also features a focus limiter (with three options: FULL, from 3.3 to 8 meters, from 8 meters to infinity). Here you can also find the serial number of the lens and information that it was produced in Japan.
The next part is much wider, with a very solid and significantly big ring which turns smoothly into equally solid tripod collar. On the ring there is a plate with the name and parameters of the lens, a loosening screw and metal handles for a strap. The whole part can be turned but it cannot be detached from the body. If you don’t need the collar the only thing you can do is to remove four screws from its base and get rid of the flange.
Further on, moving toward the front element, you see a distance scale behind a window. It is expressed in feet and meters but it comes without any depth of field scale – below you can only find the mark of focal length of the lens. On the left side of the scale there is another series of switches. The first one allows you to choose the optical stabilization unit mode (1, 2, 3). According to the producer the third, additional mode, is perfect for action photography, especially while panning because it activates the image stabilization system only at the actual moment of exposure. The next switch allows you to activate and deactivate stabilization (STABILIZER ON/OFF). Then you see a round SET button and below a slide FOCUS PRESET switch with three positions available (OFF, ON and BEEP). The FOCUS PRESET set of switches is used for saving a focusing mechanism position of your choice and recalling it at any moment. That function works in all focus modes: AF, MF and PF.
A big manual focus ring is the next visible part of the lens, as wide as 45 mm and covered by rubberized ribbing. Running through the whole distance scale needs a turn through an angle of about 200 degrees. Right behind you see a much narrower white ring, ribbed too but not rubberized (the so-called Playback ring). It allows you to focus manually in the PF (Power focus) mode and is useful for shooting video as it ensures smooth, gradual focus changes. The next ring comes with rubber ribs but it can’t be turned. It features four AF Stop Buttons positioned every 90 degrees. Then you see a characteristic green stripe meaning you deal with a DO series instrument and a hood mount.
On the front there is an element about 95 mm in diameter which doesn’t move and is hidden inside the barrel near 2.5 cm deep.
When it comes to the optical construction you deal here with 18 elements positioned in 12 groups. Canon boast of using one low-dispersion fluoride element (UD), one aspherical element and two DO elements glued together. An element belonging to the stabilization unit was covered by Subwavelength Structure Coating (SWC). Inside you can also find a round aperture with nine blades which can be closed down to a value of f/32.
Buyers get a big hood with a matching soft front cap, a rear cap, a comfortable neck strap and a special hard case.
Optical stabilization
In the case of the Canon’s EF 400 mm f/4L DO IS USM II optical stabilization unit the producer claim four stops improvement. Of course we decided to check it. We took several dozen photos at every exposure time ranging from 1/400 to 1/6 of a second with the stabilization switched on and off and then we determined a percentage of blurred photos for each set. The appropriate graph, showing that percentage, correlative with the exposure time expressed in EV (with 0 EV being an equivalent of 1/320 of a second) you can find below.
The maximum distance between both curves reaches 4 EV exactly so the declarations of the producer are in perfect accordance with our measurements. A round of applause!
