i will be shooting from the baseline so i'll prbly look in to the 50mm or 85mm but i doubt i will need the f1.4 ... 1.8 should be enough.
are there any off brands that someone can recommend?
and i have another question. one of my friends has a 24mm-105mm f/4 canon lens which cost $1200. i dont understand why it cost 4 times more than my 18mm-105mm f/3.5-5.6 nikon lens.
The 24-105 is a constant f4 lens. be it at 24mm or 105 mm. Your 18-105 is f3.5 at 18mm and f5.6 at 105mm. Constant aperture lenses are more costly to build.
Secondly the 24-105 is Canon L glass. Top of the line materials and construction. It is their for a lack of a better term, "Pro glass."
The Nikon 18-105 is a consumer grade lens utilizing consumer grade materials and construction. That doesn't make it bad, but the build of Canon's L glass and Nikon's top line glass is noticeably better and becomes more noticeable over the years. The just tends to be less issues with top line glass over time as it is built to be used day in and day out.
As for the lens choice, one thing to consider, all lenses tend to be a touch soft wide open. The 50 f1.8 at f1.8 will be that way. The 50 f1.4 will be that way at f1.4. But the 50 f1.4 can be stopped down to f1.8. Not much of a difference, but it can provide some IQ improvement.
Stopped down to f2 or f2.8 and you may see a noticeable difference. I prefer the fastest glass that will do the job and then stop it down towards f2.8 while maintaining fast shutter speeds at as low of an ISO as possible. Lighting conditions will not always let me get to f2.8 but any stopping down will help a bit.
One of the things about action/sport photography is that it is very demanding on equipment. Often times more so than most other photography venues. Of course the trade off is the fact that the 50 f1.4 will be more expensive than the 50 f1.8.