Edward, I shot the C-Sonnar and Planar as a pair for 3 years. My C-Sonnar is factory "optimized" for f/2.8 which is where I like to shoot it most, and I like it a lot w/ my M9. It gives a certain dimensionality I value (apologies for lens-speak).
If the sonnar at f/1.5 disappoints, you might have it optimized at f/2.8 (or as D&A suggests at around f/2.2-2.4) and try it at f/2.8 where it still really excels, produces lovely blur, and is quite a bit sharper. And you still have f/1.5 speed when you need it - just learn to lean in a bit when up close at f/1.5.
If having two lenses to get sharpness and also speed when you need it is bothersome, there is always the 50 lux asph, as other have said. I started shooting with one late last year. It is a spoiler of the first order. I shoot in dim venues a lot. The 50 asph just seems to lift light so sweetly.
teera: lovely portraits of a lovely child
If the sonnar at f/1.5 disappoints, you might have it optimized at f/2.8 (or as D&A suggests at around f/2.2-2.4) and try it at f/2.8 where it still really excels, produces lovely blur, and is quite a bit sharper. And you still have f/1.5 speed when you need it - just learn to lean in a bit when up close at f/1.5.
If having two lenses to get sharpness and also speed when you need it is bothersome, there is always the 50 lux asph, as other have said. I started shooting with one late last year. It is a spoiler of the first order. I shoot in dim venues a lot. The 50 asph just seems to lift light so sweetly.
teera: lovely portraits of a lovely child