- This might help you How to Focus a Nikon DSLR Manually - For Dummies
- Forget about Big Glass. ZOOM lenses tend to restrict creativity. MOST DSLR owners buy a Zoom Lens for the reach but will leave the Camera at home due to the Bulk and Weight. Go for Prime lens. As you said you shoot People & Nature, get the "Nikon AF-S DX 35mm f/1.8G Lens" that sells for around 10k.
I spent Rs. 25k for a tiny 35mm lens for my NEX5R which is in E-mount. This 35mm stays in my Camera most of the times. And the Camera stays with me 50% times, whenever I leave home. For APS-C camers, it has 52mm equivalent FoV and is just perfect
. Till one sees thro a 35mm lens, it is difficult to understand the benefits. PS
: Before committing yourself to a Zoom Lens, do consider how and whereall you'd carry it around. I find MOST DSLR owners using their mobile Cams. DSLR with big Lens has a tendency to be at home. Ask your friends.