Immediately zoom back to 100% in Photoshop with Command+1
You can immediately zoom back to 100% on any document within Photoshop by hitting Command+1 (yes like the number one). If you’re not a fan of keyboard shortcuts, you can also just double-click on the magnifying glass icon to zoom back to 100%.
I’ve been using Photoshop for years and I didn’t know this until I came across it on TheGraphicMac.com. Granted I’m not a big keyboard shortcut explorer, but sometimes these little tips really amaze me with how useful they are.

And double-clicking the hand tool icon (just above magnifying glass icon) will fit the document to the document window.