Short review and comparison - 400 f/4 DO IS USM

Thanks to my friend Andrea "Elefantino", I've had the possibility to use the interesting Canon 400 f/4 DO IS USM

The Canon 400 f/4 was the first lens with a diffractive optic element. When Canon showed for the first time the prototype of this lens (september 2000), it was regarded as a great innovation - for the first time, a diffractive optical element (i.e. a kind of fresnel lens) was used in a photographic lens. The DO element allows to create smaller and lighter lenses, while eliminating chromatic aberration. It seemed that Canon was seriuosly intentioned to introduce a new lineup of DO lenses, and there had been even some rumors about a 200-400 f/4 DO IS and a 500 f/2.8 DO IS, but now, seven year after, the only other DO lenses that had been announced is a mediocre 70-300 zoom. Is the Canon 400 f/4 DO a failure or it is a truly innovative lens?

Thanks to my friend Andrea "elefantino", I've had the opportunity to use this interesting lens. Even though it is not labelled as "L", the built quality and the autofocus is the same of the best L superteles....it has a very sturdy structure in magnesium alloy and it is weather sealed.

The autofocus is extremely fast and, of course, it has also full time manual focus. The image stabilizer actually is better than the IS of the other supertele - while the 300/4002.8/500/600 have the second generation IS, the 400 f/4 DO has the more recent 3rd generation IS, that is a little more effective.

The great advantage of this lens is, of course, weight and size. It is light! It is incredibly light....almost 1kg lighter than 300 2.8 and 2kg lighter than the 500 f/4. It is a joy to handhold, even if you are not used to superteles, you wouldn't have problems handholding it all the day. And it is so small! It is just a little longer than the 100-400, and it fits easily every camera bag. There is no doubt that in terms of reduced weight and size Canon has accomplished its goals.

But awesome built quality, AF and IS are not enough to make a great lens: the image quality is what really makes the difference. In spite of the fantastic built and the price, Canon has not labelled the 400 DO as L - and there is a reason. The image quality if good, but not as good as you can expect from a $5k lens: it is not on par with the other superteles, and even some much cheaper lenses give better results. Wide open at f/4 the image quality goes from acceptable to good, depending by the light - it is quite good in direct light, while it is much worse in backlighting. From f/5.6 it is excellent. The following images are 100%, unprocessed, crops taken with my 20D, the 400 DO and the 100-400 L IS.

Canon 400 f/4 DO at f/4

Canon 400 f/4 DO at f/5.6

Canon 100-400 f/4.5-5.6 L IS at f/5.6

The big problem of DO lenses is the flare, that reduces the contrast: wide open, other than a visible loss of sharpness, the lens really lack of contrast - it is worse than the 100-400 L or the 300 2.8 + 1.4x TC. At the same aperture (f/5.6), the 400 DO is a bit sharper than the 100-400 L IS, and it is on par with the 400 5.6 L.

I wouldn't hesitate to use the 400 DO at every aperture - even at f/4, it is surely usable. On the other hand, if you want the perfect sharpness you have to stop down by one stop - but this nullifies the biggest advantage of a f/4 lens. If you plan to shoot routinely at f/5.6, the 100-400 or the 400 5.6 might be better choices - they are even smaller and lighter, and they are much cheaper. The 400 DO has slightly better image quality than the 100-400 at the same apertures (but it is not better than the 400 5.6), it has 3rd generation IS and slightly faster AF: you have to evaluate if these advantages are enough to justify the price difference.

Another lens that is often compared with the 400 DO is the 300 2.8 IS. If you don't mind the 1kg difference between 400 DO and 300 2.8 + 1.4x TC, the latter is a better choice, it is sharper and it gives the possibility to photograph at f/2.8 when you need this aperture.

Moreover, in the same price range there is the Canon 500 f/4 L IS USM, that is a better lens in every respect, except the bulk.

The 400 DO is a interesting lens, but I'd recommend it only if you absolutely need a 400mm with f/4 aperture and very little weight. If you don't need the f/4 aperture, I'd suggest either the 400 5.6 or the 100-400; if you don't mind the weight and size, the 300 2.8 or the 500 f4 are much better choices.