The Photomerge dialog box contains tools for manipulating the composition, a lightbox for storing source images that are not in use, a work area for assembling the composition, and options for viewing and editing the composition. You can also zoom in and out to better see the alignment of each file.

and
drag within the work area. Or, drag the view area (the red box)
or the scroll bar of the navigator.
and
Zoom Out icon
, or
use the Zoom tool
. Hold
down Option to zoom out with the Zoom tool.
, click
the image you want to rotate, select the Rotate tool
and
then drag in a circular motion around the image.
Make sure Snap To Image is selected to
automatically snap overlapping images into place when a commonality
is detected.