I have not had any trouble with the 35/1.2 either on the R4a. I have not used it a lot, but I have done it. Remember the 35mm framelines in the R4 are smaller than in a .72 Leica, R2 or ZI. I have found that they CV 35/1.2 intrudes into the same amount of the 35mm framelines on the R4a as it does into those on my M6. I am guessing the window of the R4 is closer to the lens than in the M6, but the decreased magnification offsets amount of finder blocked. To my eye this is a true statement for the 28 Ultron too.