Manual Focus with a D40X, D40, D60 - or any other Nikon

If you use a low end Nikon DSLR like D40, D40X or D60 together with a number of lenses without built in autofocus, like Sigma, Tamron or even Nikon's own AF 50 f1.8D, then you have to use manual focus - that is, you have to move the focus ring around the lens until you are in focus.

Nikon has an in-focus indicator, that lights up in the form of a green dot in the viewfinder to show when you have the subject in focus:



The in-focus dot is there on most other Nikon cameras as well, in case you choose to use manual focus on them.

(I feel like an idiot for not having realised this before. I probably shot around 1000 pictures with manual focus without looking for the green dot. But it is quite well hidden in the manual.)