print_r($exif['photo']['exif']);

Array
(
    [0] => Array
        (
            [tagspace] => IFD0
            [tagspaceid] => 0
            [tag] => Make
            [label] => Make
            [raw] => Array
                (
                    [_content] => NIKON CORPORATION
                )

        )

    [1] => Array
        (
            [tagspace] => IFD0
            [tagspaceid] => 0
            [tag] => Model
            [label] => Model
            [raw] => Array
                (
                    [_content] => NIKON D5100
                )

        )

    [2] => Array
        (
            [tagspace] => IFD0
            [tagspaceid] => 0
            [tag] => XResolution
            [label] => X-Resolution
            [raw] => Array
                (
                    [_content] => 240
                )

            [clean] => Array
                (
                    [_content] => 240 dpi
                )

        )

function search_exif($exif, $field)
{
    foreach ($data as $exif)
    {
        if ($data['label'] == $field)
            return $data['raw']['_content'];
    }
}

$camera = search_exif($exif['photo']['exif'], 'model');

$model = '';

foreach ($exif['photo']['exif'] as $data) {
    if ($data['label'] == 'Model') {
        $model = $data['raw']['_content'];
        break;
    }
}

foreach($exif['photo']['exif'] as $row) {
    foreach ($row as $k => $v) {
        if ($k == "label" AND $v == "Model")
            $needle = $row["raw"];
    }
}
print_r($needle);