Hi,
Here are some samples:
The first one shows the image on clicking the large image at the top of the page, scrolling through the images at the bottom of the page: https://acrobat.com/#d=BI-C*vM-cryysNXA9Hpt5A.
The second sample shows the image large scale at the top of the page when the user hovers over the small thumbnails at the bottom of the page: https://acrobat.com/#d=PM0g9LW70vm9UN6iGqhtXQ
These might give you a direction. You could have the large imageField in a subform, that becomes visible (giving the appearance of a popup). This would also include a close button to set the subform's presence to hidden.
Hope that helps,
Niall