Rob, it's a bit of a mystery to me why there isn't a 21mm frame for the reason you mention; it's the same field of view on the M8 as 28mm is on other M bodies.
Also, the M8's VF has slightly less magnification (.68x vs .72x) which should make that even easier.
But indeed the 24mm framelines (giving an angle of view about like a 32mm on film) is way out at the edge of the window, especially so on the M8.2 with its "more accurate" frameline mask. I have about equal difficulty seeing the M2's 35mm frame.
I use the very nice metal CV 28mm finder along with a 21mm lens on the M8, and while this is satisfactory, I'd accept less VF magnification in the camera body to get in-built frames for the 21mm.
Also, the M8's VF has slightly less magnification (.68x vs .72x) which should make that even easier.
But indeed the 24mm framelines (giving an angle of view about like a 32mm on film) is way out at the edge of the window, especially so on the M8.2 with its "more accurate" frameline mask. I have about equal difficulty seeing the M2's 35mm frame.
I use the very nice metal CV 28mm finder along with a 21mm lens on the M8, and while this is satisfactory, I'd accept less VF magnification in the camera body to get in-built frames for the 21mm.