How to Correct for a Speedboosted Fisheye Lens?

Software darktable
1

I have somewhat interesting setup for astrophotography:

Camera: Fuji X-T200
Speedbooster: Viltrox EF-FX2 (Latest Firmware)
Lens: Rokinon 12mm Fisheye F2.8 (Canon EF Mount)

I was recommended the samyang 12mm correction on the lens correction module, but this only helps somwhat with the curvature. Setting the camera base to the Fuji X-T100 seems to crop too heavily, but using the Canon 35mm Full frame camera base doesn’t do anything at all.

I set the focal length to 12mm, the F stop to 2.8 (what the camera was set to at the time), and the distance to 1000m (infinity).

What settings would I need to correct for the distortion caused by the fisheye lens on this camera setup?

Base Picture:

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image1520×864 169 KB

Module On:

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image1521×833 172 KB

2

Since the Viltrox has its own optics, the lens correction module will likely not be much use until/unless correction data is created using both the Rokinon/Samyang and the VIltrox at the same time.

If you only care about correcting the distortion but not TCA, a more useful tool to correct this might be Hugin.

3

you need to do the lensprofiling yourself: see Create your own lens correction data for Lensfun – Kameratrollet

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