What affordable camera lens can i use to shoot the moon.i have nikon SLR D40 with me?
The most affordable lens could be the 55-200 mm or 70-300 mm lens, however to fill the frame with the moon, you will need the equivalent of a 1500 mm lens, so you are looking at buying a telescope, not a camera lens. The exposure for the moon is the same as here on earth, since the same sun is striking the moon as strikes the earth. If you are shooting at 1/250th seconds @ f/11 on earth, you will use the same setting for the moon.
All right. If you need to take a good picture of night sky and the Moon, it is good for you to get a high speed telephoto lens such as 200mm F2, 300mm F2 or F2.8 or 400mm F2.8. These lenses are expensive. So it is worthwhile to check the used camera store. If you cannot afford to get such high speed lens, 300mm F3.5 must be OK. Zoom lenses have residual aberrations and the image may be with coma when you take stars. Of course, if the zoom lens is slower speed, this issue will be solved but the shutter speed would be slower and easily affected by image shake. I would not specify any specific Nikon lens but you can speak with camera shop people or call camera stores. They must know a lot about the situation. Or you can email to Nikon by way of the website. And you can contact Nikon service center of Tokyo too. Visit the website of Nikon or google Nikon. Good luck. I have worked for a camera maker before. If you have further questions, it is all right to email me, if you want.