Focus vs Focus CK.
As noted earlier, the standard version of Focus is available exclusively on the Mac App Store, while the professional-grade Focus CK is only available on the Skylum website as part of the Creative Kit bundle.
Focus is clearly an affordable and very popular tool for beginning photographers and hobbyists alike to set their images apart and achieve a perfect artistic touch. Focus CK includes a several key features that make it essential for serious pro-sumers and professionals who want to get the most out of their craft:
Can be used as a plug-in for professional photo applications like Adobe Photoshop and Lightroom or Apple Aperture.
More powerful Blur controls such as Radial and Linear Motion Blur.
Adds In Focus controls such as Sharpen and Clarity.