Some of the highlights:

• Caustics! Easy to use, and fast to render, the "missing link" in realism in today's scenes
• Pick objects, and set DOF focus point in the rendered image (IR viewport, and VFB)
• Fisheye mode for the Corona Camera
• Intel AI Denoiser (works on any CPU)
• Multiple Suns and Environments for LightMix
• New Corona Select Material and Map, so an object can "store" multiple materials or maps along with it

Read full details about all the above, plus everything else there isn't space to mention, over in the blog post.

For those of you who have tried Corona before and your 45-day trial expired, we've automatically refreshed the demo period to give everyone an extra 14 days so you can try out all the new features! Simply download and install Corona Renderer 4, and you can activate the refreshed demo period right from within 3ds Max. Enjoy!