Ophrys Photography

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Canon lens test

100-400mm f4.5-5.6 L IS USM vs 70-200mm f2.8 L IS USM mkII
used with and without converters

Having upgraded my 70-200 f2.8L IS mkI to the latest mkII version and having been very impressed with the image quality jump, I couldn't help but wonder whether the new lens was capable of matching a 100-400mm L IS when used with a 1.4x or 2x converter. If it could, then I would not need both lenses and could sell the 100-400 to save some cash.

Test setup
I set up a test using controlled conditions as follows: I used a Canon 5DmkII camera on a tripod and used a cable release even though I could achieve a very high shutter speed of 1/3200sec at 400 ISO as the light was bright. I used the widest aperture that the lens/converter combination would permit each time.The subject distance was 2.9m and the lenses and converters had been micro-adjusted previously. I focused automatically using Liveview and took images in triplicate also in Liveview to minimise camera vibrations. All RAW images were processed identically in ACR and no sharpening was applied (unless otherwise stated).

I took a series of shots at various focal lengths. The image below was taken at 200mm to give you an idea of the target - a banknote stuck to an angle bracket. The focus point is marked in red. When shooting at 100mm the target seems a long way away and great image quality cannot be anticipated when images are viewed at 100% as the number of pixels covering the target is very low, however this tough test is equal and should demonstrate differences well. The range is much better suited to the maximum 400mm focal length tests and high quality results were expected.

 

Test results


At 100mm. As expected, the quality of the small target taken with the bare lens was not terrific because of the long 2.9m shooting distance. Also remember these images are unsharpened.The differences between the lenses was perhaps surprisingly minimal.

At 140mm the bare 70-200 was looking better than the bare 100-400, but not by the margin that I expected from my real world tests. When I fitted a 1.4x mkIII converter to the 70-200mkII lens set to 100mm I could also achieve 140mm. When I did this, I could see no difference between the 70-200 plus converter and the bare 100-400 at 140mm. Just to add a couple of notes here, as I used the lenses at the widest aperture possible for each test, the 70-200 plus 1.4x was used at f4 vs the 100-400 at f5.6. Also, you may be wondering if the use of the latest 1.4x mkIII converter was the reason that the converter results were so good. I believe the answer is no - I have previously tested the two converters and I can't see any difference between them in image quality in the centre of the frame. I am sure a 1.4x II converter would have given the same result.

At 200mm the bare 70-200 beats the 100-400 as expected.

At 280mm the 70-200 plus 1.4x III had to be used at the maximum 200mm focal length and the lens was also used wide open at f4. When compared to the bare 100-400 lens at 280mm (right in the middle of its range) the difference was small but the 100-400 was better. If the 70-200 was stopped down 1 stop to match the f5.6 of the 100-400 I would expect this difference to disappear.

At 400mm. I fitted a 2x II converter to the 70-200mm lens set to 200mm to achieve 400mm as I don't own a mkIII 2x converter. The first thing I noticed was that the 70-200 plus 2x converter gives a slightly larger image than the bare 100-400 set to 400mm ! I half expected this as the 100-400 has been reported as being 380mm at the long end rather than a true 400mm - and this proves it. So how did the two compare ? Perhaps surprisingly, I could see absolutely no difference between the 70-200 lens plus converter and the bare 100-400. Once the images were sharpened with Unsharp mask (set to Amount 300%/radius 0.3/threshold 0) they both looked equally good.

Conclusions

The most significant conclusion that I can draw from these tests is that the 70-200mm f2.8 mkII can be freely used with converters and still totally hold its own against the bare 100-400 lens.I now feel that I don't need to own both a 70-200 and a 100-400 as the 70-200 mkII can do it all.

The lens is therefore extremely versatile. Firstly it is a formidable 70-200 lens when used bare as it is very sharp and has great contrast. It also has a "fast" maximum aperture of f2.8 which is useful when light levels drop as higher shutterspeeds can be retained for longer as the wide aperture lets in more light.

The fast f2.8 aperture is a further advantage when using extenders, as autofocus is retained on all Canon digital SLR cameras even with a 2x converter fitted. The 4 stop image stabiliser (vs the 2 stop of the 100-400) offers further advantages when hand-holding and shooting in lower light levels. Finally the f2.8 aperture of the bare lens also means that more of the sensitive cross-type autofocus sensors come into play and should yield faster and more accurate autofocus. I can confirm that the bare 70-200mm f2.8 mkII autofocuses significantly faster than the 100-400 which is very useful when photographing birds in flight for example. The 70-200 plus 1.4x converter still focuses pretty fast and although it is hard to gauge, I feel i t is still as snappy as the bare 100-400 lens.

In summary, if you own converters already, the 70-200 f 2.8 mkII can probably replace the 100-400 lens. You don't really need both and as I write this, mine is up for sale on Ebay ! However, the 100-400 is still a great lens and if you tend to only use the longer focal lengths most of the time, then it is still the cheaper alternative. I have found that since I carried out lens micro-adjustments on my 100-400 it has transformed the image quality of this lens and it stood up to comparison with the new 70-200mm mkII quite a bit better than I anticipated.