It can grab images and show FPS in real time too.
Fraps is a freemium product.
Its benchmark function is free, but the screen recording lasts 30 seconds only.

On top of that, the output is watermarked.
Also, the screen capture can only take screenshot in BMP images.
The other supported image formats are only for registered users.

Its window size cannot be changed.
The Movies tab is where all configs related to video capture are located.
The output will be saved to the specified destination.
The default hotkey to take a screenshot and the output folder can be changed in the Screenshots tab.
After you register the software, its limitations will be removed.
Its a free and open source software.