While the spectrum ST4 has a built in intervolometer for regular fixed interval timelapses, true exposure ramping for chasing the "holy grail" isn't something that any motion control system on the market handles well (even if they say they do). If you are truly chasing the holy grail then check out a product that was designed with the intention of making it possible with repeatable results.
Intervalometer / Camera Controller, remote live view, real-time instant preview of time-lapse, fully automated day-to-night and night-to-day exposure ramping, wide temperature range, OLED color screen, motion integration, long-term/scheduled time-lapse, integrated battery (15+ hours, can also be powered externally via any USB power source).
Supported Cameras:Nikon, Canon, Sony Alpha, Panasonic GH3/4/5, G9, Fuji X-T1/2/3, GFX & Olympus OM-D.
Includes USB charging cable