How can I determine fully illuminated image circle from Specifications?

[900SL]

Hi all

Intes Micro M76 180mm f6, stated to be good for imaging, but I would like to know what sensor you could use before vignetting became an issue

 

Specs:

Clear aperture ----180mm (7.1”)
Focal length ----1068mm ( 42”)
Tube diameter ----219mm (8.6”)
Tube length ----1067mm (42”)
Tube weight ----13.6kg (30lbs) including tube rings
Diameter of secondary mirror ----36mm (1.4”)
Diameter of central obstruction ----20%
Meniscus ----BK7 less than 1% reflection broadband multicoated
Mirror ----Sital 95% reflective SiO2 coated.
Tube ----Aluminum fully baffled cream colored.
Focuser ----low profile with draw tube and adapter
Finder ----8x50 mm with quick release bracket
Camera holder ----Yes
Optical quality ----1/7 to 1/8th wave or better