IMP - By default the app takes pictures in 5MP resolution. If you want to take pictures in 8MP resolution, just disable 16:9 mode in settings.
Just like all other Xperia SP users, I was completely dissappointed with the phone's horrible camera. Upon further investigation I realised that the issue was due to the unpolished and half-baked stock camera app and therefore some users posted Xperia M's camera app which performed better.
After some little searching on the internet, I found Moto X's camera apk.
The app does wonders on our device and performs better than Stock camera or google camera app, especially in terms of auto-focus department.
So, I suggest everyone to try it out. I am attaching the apk to the post.
Works on stock as well as custom ROMS.
NOTE - Produces great results while taking pictures of 'texts and documents' where stock app fails terribly.
Bugs - Not all features are working (eg HDR mode). But the app does a pretty decent job.