3dZoom will instantly display a large, zoomed version of your product's image when a visitor places the mouse cursor on top of the image. Uploading a large image to the product via the store manager automatically enables the 3dZoom without the need to upload additional images via FTP.
To enable this feature:
Go to Settings > General > Store Settings.
Once there, click on the Product Display tab.
Scroll down to the "Products" section and look for the "Enable Product Page Zoom" setting.
Select 3dZoom from the drop-down menu and click the Save button found along the top right of the Settings page.
Your products will now have a zoom function when moused over. Your customers can also click on the image to instantly zoom the whole image.