Which lenses work well for freelensing on a Nikon DX body?

Freelensing shifts the lens away from the sensor, which acts a lot like adding extension tubes. That moves the focusing range much closer, so with many normal lenses everything at typical shooting distances can become out of focus. That’s why you’re seeing mostly near-focus or macro-like results.

For easier freelensing, people generally have the best results with:

• a prime lens rather than a zoom
• roughly 35–85mm focal lengths
• a fast maximum aperture
• a hard infinity-focus stop
• on Nikon, a non-G lens, since many G lenses stop down when detached

A 50mm prime is a common choice. In Nikon terms, the 50mm f/1.4 AF-D is often recommended, and a 50mm f/1.8 can also work well, especially for macro-style effects.

If you want to focus at more normal distances while holding the lens away from the mount, a lens designed to sit farther from the film/sensor plane—such as some medium-format lenses—can help.

So the issue is less that your technique is wrong, and more that freelensing naturally pushes focus very close unless you choose a lens that’s well suited to it.