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!


1 Answer 1


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.

  • 1
    \$\begingroup\$ All of my lenses are manual zoom, and all report the (approximate) focal length to the camera. Of course it's only metadata, but profile based distortion correction could be a problem with wrong data. \$\endgroup\$
    – ths
    Commented Feb 22, 2017 at 12:32
  • \$\begingroup\$ @ths what camera body & lenses in your case? I've not used the camera in question, so it's certainly possible I've reached the wrong conclusion. \$\endgroup\$ Commented Feb 22, 2017 at 12:43
  • \$\begingroup\$ I have used many other manual zoom lenses with this body, and it should always report back the current focal length. \$\endgroup\$
    – Tindra
    Commented Feb 22, 2017 at 12:46
  • \$\begingroup\$ @Tindra I use back button AF with a 5D Mark II, as well as a 5D3 and 7D2. I use an EF 17-40mm quite frequently on the 5D2 and the combination reports focal length values all the way from 17mm to 40mm and anywhere in between. \$\endgroup\$
    – Michael C
    Commented Feb 22, 2017 at 17:06
  • \$\begingroup\$ Thanks, good to know @MichaelClark . It didn't solve my issue so i contacted Canon. They thought it might be either a software issue or a not functional pin/contact. Anyway I've send it away to them for a repair! \$\endgroup\$
    – Tindra
    Commented Feb 23, 2017 at 7:15

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