dear Jessica D'Amico, thank you for your reply but I got it working just with embedding template technique:
{exp:channel:entries channel="journal" limit="1" url_title="{segment_3}" disable="categories|member_data|pagination|trackbacks" cache="yes" refresh="512640"}
{exp:channel_images:images entry_id="{entry_id}" field="journal_images"}
{if "{image:total}" > 1}
{if "{image:total}" == "{image:count}"}
{embed="moyseion:journal/_slideshow-em" entry_id="{entry_id}"}
{/if}
{/if}
{/exp:channel_images:images}
{/exp:channel:entries}
and this is my embed template:
<!--altre foto-->
<div class="mini-page-wrapper" data-role="story-part" id="part-2">
<section class="mini-page mini-page-semicompact">
<header class="block-stack">
<p class="block-right buttons-compact mobile-sm-1col mobile-sm-stack-compact">
<a data-role="prev-section" href="#part-intro" class="button-like button-icon button-up bg-accent-darker">
Previous</a>
<a data-role="next-section" href="#comments" class="button-like button-icon button-down bg-accent-darker">
Next</a>
</p>
<h1 class="three-fourths-page h2-like mobile-sm-1col mobile-sm-stack-compact">Altre foto:</h1>
</header>
</section>
<div data-role="slideshow-em" class="slideshow-em offset-parent margin-bottom-1x">
<nav data-role="slideshow-em-prev" class="slideshow-em-nav corner-top-left fit-container-left high hidden">
<button class="slideshow-em-button button-icon button-prev bg-accent-darker">Previous</button>
</nav>
<nav data-role="slideshow-em-next" class="slideshow-em-nav corner-top-right fit-container-right high hidden">
<button class="slideshow-em-button button-icon button-next bg-accent-darker">Next</button>
</nav>
<ul data-role="slideshow-em-tray slideshow-lazy" data-set-url="" class="slideshow-em-tray reset-list offset-parent clearfix">
{exp:channel_images:images entry_id="{embed:entry_id}" field="journal_images"}
<li data-role="slideshow-em-slide" class="slideshow-em-slide">
<figure>
<div data-role="open-lightbox-image"
data-title="{title}"
data-src="{pre_proxy}{image:url:journal}{post_proxy}"
class="{image:switch='media-wrapper link-like bg-placeholder bg-loader|link-like media-wrapper moblg-col moblg-1-2 mobl-sm-hide bg-loader|link-like media-wrapper moblg-col moblg-1-2 mobl-sm-hide bg-loader'}">
{exp:ce_img:pair src="{image:url:journal}" width="220" height="220" crop="yes" cache_dir="/WebStatic/s3/Blog/" hide_relative_path="yes" hash_filename="yes"}
<img class="full-width responsive-image bg-placeholder"
data-role="lazy-image"
data-lazy-image-animate="true"
src="data:image/gif;base64,R0lGODlhCgAKAIAAAP///wAAACH5BAEAAAAALAAAAAAKAAoAAAIIhI+py+0PYysAOw=="
alt="{if image:description}{image:description}{if:else}{title}{/if}"
data-lazy-image-url="{aws_url}"
/>
{/exp:ce_img:pair}
</div>
{if image:description}
<figcaption class="slideshow-em-caption">
<a data-role="open-lightbox-image" data-src="{pre_proxy}{image:url:journal}{post_proxy}">{image:description}</a>
</figcaption>
{/if}
</figure>
</li>
{/exp:channel_images:images}
</ul>
</div>
</div>
<!--altre foto fine-->