The UI Magnifier
This is a loupe that magnifies the screen, making it easier to read. This is useful on small screens running at high resolution. It magnifies what is already on the screen. If you hold it over an image, it magnifies only what is on the screen and does not really look at the underlying pixels from the larger image, so it is inaccurate. There is a dedicated image magnifier available that can be accessed from the image popup menu.
To start the magnifier, go to the Tools menu and select the ‘UI Magnifier’ item. You can left-click and drag the magnifier around the screen.To hide it, do it again or press the escape key on the keyboard. There is only one level of magnification.
Image Browser Magnifier
Double-click on the main image in the image browser, or right-click on the image to access the magnifier in the popup menu. This brings up a magnifier that you can zoom in and out of the real large image data. You can left-click and drag the magnifier around the screen. To hide the magnifier, double-click on it again. You can zoom in and out with the mouse-wheel too.