HD PENTAX-D FA★ 50mm F1.4 SDM AW vs smc PENTAX FA 43mm F1.9 Limited image quality comparion test videos published by Li (the CameraVille).
Test Pt. 1/2 – Stills Test
Test Pt. 2/2 – Portrait/Landscape Test
But… There is a mistake here technically. Object has to be in same dimensions on the frame for 100% right comparison. For example if we use 1 m -lens to object- distance for a 50 mm lens, should be ~0.86 m for a 43 mm. Otherwise this technical mistake effects bokeh dramatically!
Also a 50 mm lens gives more smooth bokeh -than a 43 mm lens- on the background thanks to its +7 mm tele magnification factor. So would be a mistake to say: “HD PENTAX-D FA★ 50mm F1.4 SDM AW is better than the smc PENTAX FA 43mm F1.9 Limited about bokeh quality.” etc.
To understand roughly you can check Michael Bemowski’s DOF Simulator!