ScreenCapture

ScreenCapture is an application that you can configure to automatically take screenshots at a regular time interval. It comes in handy when you want to leave the computer unattended and later find out the activities it performed while you were away.

Portable tool with a simple interface

It's not wrapped in a setup pack, so you can save the downloaded .exe file to a custom location on the disk or copy it to a USB flash drive, in order to easily run it on any PC. It doesn't need DLLs to run or add new entries to the Windows registry. On the other hand, it creates and updates an .ini file to remember your configuration on exit.
The main panel doesn't have attractive graphical elements, as the tool prefers to focus on functionality. However, it has a neatly organized structure with separate areas for configuring capture settings, editing image properties, previewing photos, and customizing general options.

Set capture, image and general preferences

It's capable of capturing the full screen, active window, or a user-defined area by specifying the left and top margins, along with the region's width and height.
When it comes to image properties, you can indicate the saving directory, format (JPEG, GIF, BMP, PNG) and base of the filename, append a number to the filename and increment it for each new file, adjust the JPEG quality, set the capture frequency (seconds), and remove the "ScreenCapture" label from the image. Plus, you can run a simulation to make sure all settings are to your liking.
As far as general options are concerned, you can ask the application to start taking snapshots automatically, minimize to the systray to become non-intrusive while enabling you to carry on with your normal PC activity, and to start minimized.

Conclusion

Although it's pretty old, it ran smoothly on newer Windows versions in our tests. ScreenCapture features straightforward and intuitive options for capturing screenshots automatically, and it can be used for free.