R6 mark ii not communicating with Samyang EF 85mm MF lens

[EduardoMercado]

Hi, I have an EOS RP and have been using a Samyang XP 85mm f1.2 manual focus lens with an EF mount with no problems using an original Canon EF to RF adapter. I recently bought an R6 mark ii and when using this same adapter and lens, the place where the aperture is displayed disappears and taking a picture leads to a black screen that does not go away even when turning the camera off. If I take the lens and adapter as they are and use them on the RP, they work again. Other lenses work fine on the R6mii so I don't think the pins are damaged (plus it is brand new).

I have tried turning on the Release shutter w/o lens and turning the stabilization off with no success. 

Any help would be well received.

[Danfaz]

I looked through all the R5 firmware updates (see link below), and do not see any mention of fixing issues with Samyang/Rokinon lenses. I doubt they would, considering they asked Samyang to cease making AF RF lenses.

https://www.usa.canon.com/support/p/eos-r5#idReference%3Dadvisories

[David-R-M]

I bought the Samyang because at the time there was no equivalent made by Canon. However, as I have read, Canon does not seem to encourage third-party equipment, whilst other camera manufacturers regard having third-party lens available makes their product line more attractive. I am not even sure that Canon publishes their communications protocols, which might explain the current mismatch as third party companies presumably have to work out the protocol by trial and error.

I see that Canon now sell a very cheap16mm f/2.8 RF lens, which is probably the best way forward as for occasional use I don't need an "L" lens. Still, it is annoying to have a lens in "as new" condition which won't work due to what is probably a minor firmware bug...

Of course, as my Canon RF lens all work perfectly on the R6MkII, the responsibility must ultimately lie with Samyang. However, my attempts to find the address of a support service from Samyang have so far all failed (and of course the lens is out of guarantee by four months).

P.S. Somewhere on a web site (DP Review?) I read a report from someone who said that an R5 update stopped his Samyang lens working, but a later update (I think he mentioned 1.3) fixed it again. Clearly, Canon didn't mention Samyang in the release notes.