The product page has an option that allows a user to hover on the product image that will generate an enlarged image.  This option is known as JqZoom in the Prestashop 1.5 Administration Panel. If the option is diabled, the remaining display option is called "thickbox." The following tutorial will walk you through setting the option to use or disable jqzoom.

Enable JqZoom instead of Thickbox on Product page in Prestashop 1.5

1. Login to the Administration Panel as an Administrator
2. Hover over the menu bar where it says PREFERENCES, and then click on PRODUCTS in the drop down menu. Scroll down the list of options and look for Preferences: Product page.  Select Enable JqZoom instead of Thickbox on product page in the menu as shown below:
   
   
   
   
3. Select YES to enable JQZOOM or NO to disable the option.
4. Select the green SAVE button in the top right hand corner of the page to save your selection.

When you enable JqZoom, you will see the following displayed when mousing over product image:

JqZoom enables the user to look at the product closesly while remaining on the product page.  Remember that the details shown in the zoomed image will depend on the original image used for the product.