The Sigma 30mm (f:1.4) has had people say bad words…

I have been using one sample occassionally for well over a year with fairly good results, no wonders but good results.
Have a look here – this is a 100% crop out of a “Straight Out Of Camera” 12MP photo:

… and here is the original photo it comes from, can you find where I cropped it out?

Yes, that is correct – it is that tiny little moon in the upper part of the image!
That is a huge digital zoom, from 12.2MP to 0.24MP – may I guess it is approximately equal to 50x digital zoom?

I’d say: think a bit on the scale of what you’re commenting. Getting this kind of crops to stay sharp and detailed is at the very limit of the current technology. This image was taken with a semi-pro level camera (Nikon D300), the result with a pro level camera (e.g. D700, D3 or similar) and equally “better” lens would be just slightly better.