I'm not so sure. Samyang lenses require an external USB dock, which neither Sigma or Tamron need for their E-mount lenses. Also, Sony camera FW updates have been known to interfere with Samyang lens compatibility (ex: The Sam/Rok 45mm f/1.8 FE lost infinity focus with the A7III fw 3.01 update). The Samyang 50mm 1.4 FE to-date has received 32 firmware updates which seems a bit extreme.They reverse engineer the mount? Why? Unlike Canikon, any maker can register with Sony for a royalty-free license as long as they are willing to sign an NDA (non-disclosure agreement). Seems like a no-brainer from a business standpoint.