Canon 200-400 f/4 reviewed by "Chasseur d'Images"

Started Jun 20, 2013 | Discussions thread
Oldvic
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Re: Canon 200-400 f/4 reviewed by "Chasseur d'Images"
In reply to mattr, Jun 26, 2013

mattr wrote:

The problem is that resolution numbers at f/16-f/32 tell us very little about the optical characteristics of the lens. This is too far in diffraction territory, even with the relatively large 5D3 pixels. Differences will be caused mainly by errors or experimental flukes that affect the effective f-ratio, such as caused by focus distance. Of course, these results are also of pretty much zero practical relevance, IMO.

There is a reason why lens test sites that know what they are doing (e.g. Photozone) report MTF results usually only up to about f/11.

I'd recommend taking a look at the mag, as there's a lot more to the test than what I've reported here (test on a 700D, field use notes, etc.).

In order to test a very sharp lens (such as the 200-400/4) and to establish effects of TCs one should use the camera with the smallest pixels possible. So the test results from the 700D should be more informative. The 5D3 would be necessary only to analyze full frame edges.

This in to reply to both your last comments. With the stacked converter tests, I chose to report the best and worst image quality possible with the different apertures, as it seemed to me the most useful information for that scenario. The graphs have other possible apertures, but they aren't the extremes of the image quality interval.

When you're on a focal length limited situation, it's useful to know what you can expect when stacking converters, and the information provided by CI allows us to get a fairly good idea about this.

Anyway, now we have DXOmark's test, which is open-ended about sharpness, so CI's test (which refers to an A3 print size) becomes less important.

Cheers

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Sorry, I just don’t feel funny today

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