Just installed the new Metabones firmware 2.7 for the Canon EF to MTF and tested my Sigma 18-35mm f1.8 lens. My thanks to Andrew Reid from EOSHD for spotting the new FW was available.
As you can see (above), finally the Sigma 18-35mm f1.8 works fine on the GH5 with some barrel distortion as you would expect but strangly* no vignetting. This was photographed in 16:9 @ the 18mm end of the lens.
*Strangly : Last night I shot this just after applying the new 2.7 firmware and it clearly shows vignetting from the APS-C Sigma 18-35mm f1.8 lens @ the 18mm end.
I shot this today and apart from a different white balance (I did WB the GH5) there is clearly no vignetting issues. Some would say there must be a 2x digital switched on, no I clearly checked that all digital converters etc were on the off position and shot the same scene on both GH5s. The one thing I do notice is the background shallow depth of field is different between last night and this morning, its almost as if the Speedbooster is not giving me and extra f stops.
UPDATE : Answer, its the wrong adapter, I have 2 adapters from Metabones the 64x Speedbooster and a Metabones Canon EF Lens to Micro Four Thirds T Smart Adapter.
It was the Smart Adapter that was on the lens on day 2 !
- Supports only Panasonic GH5, GH4, GH3, G3, G5, G6, G7, G10, GF3, GF5, GF6, GX1, GX8, GX80/GX85, Olympus E-PL7, PEN-F, Blackmagic Cinema Camera with Micro Four Thirds mount**, Pocket Cinema Camera*** and Micro Cinema Camera***
- EF-S lenses require modification to fit or may remain incompatible even after modification (but third party DX lenses can be used without modification)
- On GH5, Speed Booster XL can be used with full frame lenses only. DX lenses are unable to cover full-sensor width readout + in-body image stabilizer (IBIS)
- EF-S and third party DX lenses does not cover the full Micro Four Thirds sensor in still photo and FHD video (but will cover 4k video mode on GH4, GX8 and GX80/85).