Zoom. A seemingly basic and boring function. You click, your image gets bigger, yippee. But think about it for a second, you probably use the zoom function a lot - checking sharpness, looking for artifacts - more than you might even realize. And being Lightroom, there are of course multiple options to the zoom tool, so let's take some time and explore it a little more.
In the top portion of the Navigator section of the Left Panel you will find the options for the Zoom Tool. But keep in mind that there is no actual tool to select - it's not like the Adjustment Brush or Clone Tool. You can Zoom in on your image by using the controls in the panel or by tapping the "Z" on your keyboard - that will zoom in on the last place you clicked with the zoom tool. Alternatively, you can use the Spacebar to access the Zoom Tool. When you click and hold the Spacebar you will see a magnifying glass that you can move around your image to the location that you want to magnify. Upon clicking and zooming in you will see a hand that you can then click and pan with.
In that upper portion of the left panel you will see the magnifying ratios for the zoom tool. First you have the default zoom views - FIT and FILL. Clicking the FIT option causes your image to expand or contract to a size that FITs entirely in the viewable area - you will see the whole image. You will also likely see some background color as well (gray by default). When you click on the FILL option it will cause your image to expand or contract to FILL the entire viewing area - leaving NO background is visible. Think of FIT and FILL as your default sizes and also think of them as being completely separate from the other zoom ratios (I'll explain why a little later). So FIT = fit the image to viewable screen and FILL = fill viewable screen with image.
After FIT and FILL we have1:1(100% pixel view) followed by the other zoom ratios that can be selected by tapping on the double arrows to the right of the magnification values. 1:1, like FIT and FILL, is static - you can't move or interchange other values in it's place. The other ratios, however, can be adjusted. From as small as 1:16 and as magnified as 11:1. Why would Adobe choose 11:1?? Well it's one of my favorite little Lightroom secrets. Did you ever see the classic movie This Is Spinal Tap? Well, it's a reference to that movie. Check out the clip below if you haven't seen the movie or if you just want a good laugh!
Above are sample images at all the zoom different magnifications.
Earlier I advised you to think of FIT and FILL separately from the other zoom magnifications. Here's why - when you zoom in Lightroom will go the last magnification you had selected, 1:1 for example. When you zoom out Lightroom will go to the last screen mode you selected, FIT for example. Stick with me for a second - so if you click on FIT, Lightroom will FIT your image into the viewable screen area - when you click 1:1 Lightroom will zoom to a 100% pixel view and when you tap the "Z" key (or use the Spacebar to activate the zoom tool and click with the magnifier) Lightroom will toggle between FIT and 1:1. In another example, If you click FILL, the image will fill your viewable area and if you then select 1:2 for the zoom magnification, you will get a 50% magnification view. So the zoom tool would then toggle between FILL and 1:2. Make sense? So, it has helped me in the past to think of them separately and then I remember better what will happen when I use the zoom tool.
There is one last feature of the zoom tool that you should know and it's hidden in the Preferences Menu. If you navigate to Preferences > Interface you will find, toward the bottom, an option titled "Zoom Clicked Point To Center". If you check this box Lightroom will center (the best it can) where you click with the Zoom Tool. If you leave the box unchecked (my personal preference), Lightroom will magnify and leave your cursor exactly where you clicked. Take a look at the video below to see the difference. There is no right or wrong option here, it's simply your preference.
Alright guys, hopefully that answers all your questions about the ever-exciting Zoom Tool in Adobe Lightroom! As always let me know in the comments or on the Facebook page if you have any questions.