Board index Photography Technical Questions dodgy exif data

Technical Questions

dodgy exif data

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penlan
 
Posts: 19

dodgy exif data

Post Sun Jul 08, 2007 8:59 pm


I apologise if this has been asked before but I have got some photos I took with my Panasonic DMC-FZ50 and in the Exif data of a few photos it claims the focal length is 7.5mm which cannot possibly be correct. Has anyone else encountered this.
thanks

penlan
 
Posts: 19


Post Fri Jul 13, 2007 11:46 am


anyone ?

andrys
 
Posts: 2701


Post Fri Jul 13, 2007 12:04 pm


penlan wrote:anyone ?


It's so bizarre that probably no one else has had experience with it.

For a couple of years, PBase has been looking for a solution to the
exif misinterpretations on the (3rd party, I think) software they're using.

I can't remember if you write cameras@pbase.com or what but it's
safest to write support@pbase.com and ask them to look at this.

Post to Q&A Form (which is for PBase matters) with a catchy title to
try to get support admins' attention to your specific problem.

"PBase: Help - why is Panasonic DMC-Z50 reading Exif focal lens totally wrong?"
Something like that.

Maybe someone from PBase will notice it. BUT be sure to write
support@pbase.com in the meantime.

ralf
 
Posts: 311

Re: dodgy exif data

Post Fri Jul 13, 2007 12:55 pm


penlan wrote:I apologise if this has been asked before but I have got some photos I took with my Panasonic DMC-FZ50 and in the Exif data of a few photos it claims the focal length is 7.5mm which cannot possibly be correct.

Actually, that's almost certainly correct! The camera is reporting the true, absolute focal length, not the 35mm equivalent (there's a different, newer tag for that [FocalLengthIn35mm instead of FocalLength], which not all cameras support). Since the camera's sensor is considerably smaller than a frame of 35mm film, so are the absolute focal lengths. On my Minolta Dimage 7 and A1 cameras, the true focal lengths are 7-50mm while the 35mm equivalents are 28-200, a so-called "crop factor" or "conversion factor" of 4.0; IIRC, the FZ50 has a crop factor of around 5, meaning that the reported 7.5mm is equivalent to 38mm for a 35mm camera.

penlan
 
Posts: 19


Post Fri Jul 13, 2007 3:33 pm


Aha, that makes sense Ralf. Thanks for your input.
Penlan

andrys
 
Posts: 2701


Post Sat Jul 14, 2007 5:24 am


Yes. I actually went to dpreview.com to look up the focal length before
writing you last night and thought they were showing higher numbers (while
the smaller ones are normally used). Maybe 35mm equiv numbers are on
your camera then? Or I checked out the wrong camera while at dpreview.

My own little Canons are 5.8mm to 22mm or 34mm, depending on the
camera, and I translate them to 35mm equivalents when thinking about
them. The numbers on the camera and software reports are the
actual smaller ones.


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