hi, i'm dont have any DSLR, but i see few of my friends have DSLR, they preferred NIKON and recommend to me to get NIKON DSLR. But I'm more interested to Sony Alpha because (1) it way more cheaper than NIKON and Canon DSLR and (2) the camera itself its more pretty compared to others. So its give more value to me and as a beginner toDSLR camera.

My question is:

1) why Sony Alpha is more cheaper than other, it is because it have less technology compared to NIKON and Canon?

2 )why many people (including professional photographer) preferred NIKON and Canon DSLR, not Sony Alpha.