Nikkor AF-S 50mm F1.4 vs AF-S 50mm F1.8?

I'm in a search for a good 50mm lens and now that nikon has launched a new 50mm f1.8 AF-S lens which is cheaper than the 50mm F1.4 AF-S. Why is there so much of price difference between F1.4 and F1.8.

i'm on a budget and would consider the 1.8 for its price but does that 0.4 stop make any difference in the optics and even the little amount of light that enters?

i own a d5000 and hence need an AF-S lens to autofocus on it

you may suggest me some similar F1 lens

Your math is wrong. The difference is 2/3 stop, not.4 stop. Not an extreme difference, but just so you know.

The f/1.8 is good enough for most work, unless you want the minimal depth of field available or are trying to work in very, very low light. How well the AF-S verion will work remains to be seen, but it should be a very capable lens.

In the amount of light, no, not all that much. Nikon's f1.4 lens do tend to be better build and have better bokeh. On the other hand, there's a hefty price difference.

If you can hold of until the new 1.8 is in the shops I'm sure we'll get a few head to head tests by then

Note that the price of the 50mm/1.4G currently is extremely high due to the disaster in Japan. It sells on bhphoto for $550 right now. Before the disaster it was at something like $350.

The strength of the 50mm/1.4 lens is less the maximum aperture, but the fact that it reaches its sweet spot much earlier than the 50mm/1.8 counterpart. The 50mm/1.4 one will be fully operational at f/2 and really shine at f/2, 8 already, while the 50mm/1.8 one will need to be stepped down to f/2.8 at least or f/3.5 for optimum sharpness. That difference is more relevant (at least to me) than the maximum aperture.

Tough choice but for the price of the 50/1.4 you can probably buy both the 50/1.8 AND the 35/1.8.