To add JComments to JPhoto, override the JPhoto image template by copying its views/image/tmpl/default.php file to your template's html/com_jphoto/image/ folder and replace:
<?php if($this->params->get('joomlacomment', 0)): // Display JoomlaComment ?>
<div class="joomlacomment-wrapper joomlacomment-wrapper-jphoto">
<?php
$option = JRequest::getCMD('option');
require_once(JPATH_ADMINISTRATOR . DS . 'components' . DS . 'com_comment' . DS . 'plugin' . DS . $option . DS . 'josc_com_jphoto.php');
?>
</div>
<?php endif; ?>
With...
<?php if($this->params->get('joomlacomment', 0)): // Display JoomlaComment ?>
<div class="joomlacomment-wrapper joomlacomment-wrapper-jphoto">
<?php
require_once(JPATH_SITE.DS.'components'.DS.'com_jcomments'.DS.'jcomments.php');
echo JComments::show($row->id, 'com_jphoto', $row->title);
?>
</div>
<?php endif; ?>
Note, this will allow the JPhoto setting for JoomlaComments (aka CompojoomComments) to be used for JComments.
Optionally, add the attached file to your component/com_jcomments/plugins/ folder to get better reporting and management in the backend...