OneLoupe is a free and portable software which will help you to Zoom part of your screen. Actually I was looking for a tool like this from long time. There are many tools like this but most of them need to be installed which is a big problem. When it comes to OneLoupe, it is a portable software software which requires no installation and the file size is also just 25KB.
I just copied it my machine and was able to use in just few seconds. It is very helpful during presentations. The small Magnifier is always ready when you need it to view all fine details on your monitor. Adjustable zoom range and the zoom factor caters to the needs of individuals. You can also get the color pixel from your desktop screen. The best thing I liked is that it offers the possibility for the quick creation of images from the zoom range, for comfortable work over the clipboard. All you have to do is just press “B” and the image of the screen that is currently zoomed is copied to the clipboard.