[Randy Wiliams]

There are lot of accessories not only for blackmagic camera but also for other camera. Technology have really made our work very easy and professional. Different equipment and accessories have been invented which have made our blackmagic camera A BIG Camera or setup.
We can use following tools

Lenses
Battery and power options
Memory Card
Cage
Shoulder rig with matte box and follow focus
Camera bag

These are few accessories which one should have with blackmagic camera.Check following links, definitely you will get some helpful information
https://www.bhphotovideo.com/explora/video/hands-reviews/blackmagic-design-digital-cinema-cameras-and-accessories

I am having following accessories
Sandisk memory card
Camtree hunt shoulder mount; matte box, follow focus are also included. And A box and power cable was free with it.
https://www.thecinecity.com/eshop/CAMTREE-HUNT-CH1-BMC-EX-BLACK-MAGIC-CAMERA-RIG-KIT.html
Cineroid Viewfinder
Monitor
https://www.thecinecity.com/eshop/Proaim-Pro-LCD-003-7-monitor-kit.html
Rain Cover
https://www.thecinecity.com/eshop/CAMTREE-Rain-Cover-Wetsuit-for-BlackMagic-Cinema-Camera-and-Production-Camera-4K-RC-BMC.html