Hello,

I wish to display under my photos, the following EXIF's data list : Model, Focal Length, FNumber, Exposure Time, ISO speed rating.
I wish to display those informations in this order and only if the data exist in the photography (otherwise, no display).

I modified the function.php file and valued in 'true' these EXIF's data only ($_zp_exifvars).

How do I do that ?

We don't recommend to hack any core files. Several functions for that are documentated like these:
http://www.zenphoto.org/documentation/functions/_functions.php.html#functiongetImageMetadata
http://www.zenphoto.org/documentation/functions/_template-functions.php.html#functiongetImageEXIFData
http://www.zenphoto.org/documentation/functions/_template-functions.php.html#functiongetImageData
http://www.zenphoto.org/documentation/functions/_functions.php.html#functiongetIPTCTag

The modifications in functions.php are very minor (I modified some 'true' and put 'false' in the place).

Finally, if all the fields which I want are 'true', I can install again the functions.php initial file.

The problem is that I don't know the php code who allow me to display the exif's data which I want, in the order which I want

Could you help me ?

An example of what I want to do :

http://www.cristaldegivre.com/zenphoto/index.php?album=fig-es-dans-ma-m-moire-&image=20081021_swiss_0324_cdg.jpg

it's wonderfull site made with zen photo

I gave you the functions to get the exif data... But try something like this:

$metadata = getImageMetadata( );
echo $metadata[];

Try the nightly build. With this release you can select which metadata fields to display via the ADMIN back end.