Camera showing incorrect used focal length in EXIF data

Question

Using a Canon 5D Mk2 with a 17-40mm f/4L lens.

Everything seems to work just fine, except no matter how i shoot, the EXIF-data will show 40mm as the used focal length, even if I know the image is taken at 17mm. Can this affect the photos in some other manner, except from acting up in Lightroom by giving me false information? (All the other information seems to be correct, ISO, Shutter speed etc).

Is there anything I can do to solve this without sending it back to canon?
(I still got warranty for the lens).

Thankful for any kind of guidance!

Carl Witthoft · Answer

EXIF is just text produced by the camera's computer. It doesn't control the contents of the pixel values.
As to why it always reports the focal length as 40 mm: you may want to study the user's manual and spec sheet for both the camera and lens carefully, tho' a quick skim doesn't appear to provide that level of detail.
followup, edited
For general info, I found a complete list  of the EXIF data this camera body records.  While that's not particularly helpful for the posted question, I noticed this comment at that page:

the one piece of basic information I really wanted to know, was I set
to manual focus or auto focus, is missing*.
*Note: I later realized that this information is included but because I dedicated auto focus to to a button on the back of my camera I can
make manual adjustments while in AF mode and my 5D is none the wiser…
stupid 5D ?

So it is possible, I guess, that some particular programmed configuration causes the camera body not to "keep track" of the current zoom setting.

Camera showing incorrect used focal length in EXIF data

One Answer

followup, edited

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