K loupe compatible with Yashica and Canon?

[Andre Langevin]

A seller told me that the K eyepiece accessories (2X focusing loupe, 
diopter correction lenses, etc.) are compatible with Yashica and 
Canon bodies and the other way around.  I should go at this shop with 
an accessory and try it to get an answer, but anybody here that would 
know about this?

Andre
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