Holding Command + Spacebar to access the Zoom tool within the Blending
options.
Adjustment Menus and Layers
The Curves adjustment, like most other adjustments, contains some handy
shortcuts. Similar to how you can cycle through the Channels in a
document, you can cycle through the adjustment’s channels using Option +
2, 3, 4, 5, etc. You can also cycle through the points on the actual curves
using - and =. With a point selected, you can nudge the points in
increments of 2 in any direction using the arrow keys. Holding Shift in
conjunction with the arrow keys moves the point by 16 units. When
working with an adjustment menu, you can toggle the Preview option on
and off by pressing P. Adjustment layers don’t have a Preview option, but
you can temporarily disable it by pressing and holding .