Focus is not working well on distances far away -endless position

The edge-to-edge sharpness of your lens is a function of the optical design much more than f-stop. What I would be more concerned with is depth of field. The important consideration is what the closest and farthest point you want to be in focus. Here are some figures that might help. For a 300mm lens focused at 200 yards (600 feet), mathematical calculations yield the following (0.03 mm circle of confusion in all cases):

f/22
Near limit = 256' 3", far limit = infinity, total depth = infinity, hyperfocal distance = 447' 5"
F/16
Near limit = 303' 9", far limit = 24,350' 8", total depth = 24,046' 11", hyperfocal distance = 615' 2"
f/11
Near limit = 359' 2", far limit = 1,821' 3", total depth = 1,462' 1", hyperfocal distance = 894' 9"
f/8
Near limit = 403' 4", far limit = 1,172' 2", total depth = 767' 10", hyperfocal distance = 1,230' 4"
f/5.6
Near limit = 447' 4", far limit = 910' 12", total depth = 463' 8", hyperfocal distance = 1,757' 7"

If your lens is 8 months old, it is still in warranty. Contact Nikon for return instructions.

Hi, first try cleaning the contact lens and body (off Camera & Without bat.) isopropyl alcohol.
Do you hear any noise in the lens when you focus on auto?
If your answer is yes, maybe the SWM has been stuck and not turning.
If you have the tools and you can carefully try to disarm it by removing the screws holding the lens connector 2 screws, then holding the back cover ring 3 screws and it comes out, you let the sw AM VR on / off, and eventually take away the bayonet unscrewing the screws that hold it.
Remove the cover and can you see

There may be some connection misaligned flexible connectors.
SWM bad.
Electrical bad component.

I hope will be usefull.
Best reggards

I fix these all the time for this problem, The focus motor is bad, Tony

Your motor may have gone bad. Try sending it to PhotoTech Repair Service in NYC. They are Nikon authorized, and can do the repair under warranty if you still have it. Also if you join they're facebook page, they will give you a 10% discount.
Here is the facebook page link, it has everything you need to send it in.
http://www.facebook.com/pages/New-York-NY/PhotoTech-Repair-Service-Inc/102527215194

Seems as if you're snapping the shutter before the lens has focused. Have you tried manual focus or single-server auto focus?

Please check your focus settings in the camera menu. Play around with the focus point from Single to 11 points. Also, try Auto mode as a quick way to test if the focus is working

Make sure your AF-switch on your camera and your lens are both turned on.

Hi - I own this lens and it manually focuses at all focal lengths (hard to see at 18mm unless your subject is extremly close). You may need to get the lens checked. BTW - Mine was set as follows when I checked for you:

• D80 was "on"
• M/A
• VR = Off
• Normal (not Active)

Hope this helps!

sir, replace ur lens image reading sensor