Tip: Rehoused lenses refer to photographic or cinematic lenses that have been taken out of their original housing and placed into a new one, typically to achieve specific technical or functional improvements. The optics of the lens remain the same, but the mechanics, body, or external features might be altered or enhanced.

Here are a few reasons why lenses might be rehoused:

1. Durability: Some classic lenses, especially vintage ones, might not have a construction robust enough to withstand the demands of modern-day filmmaking or frequent use. Rehousing can provide a more durable shell.
2. Cinematic Needs: Filmmakers often prefer lenses with consistent diameters, gear positions, and other features across a set of lenses to speed up the lens change process and to easily use follow focus systems. Rehousing can bring a diverse set of lenses into the same standard.
3. Improved Functionality: Rehousing can add features like a de-clicked aperture (removing the hard stops, which allows for smooth changes in aperture), manual focusing abilities, or enhanced close-focusing capabilities.
4. Mount Changes: A lens can be rehoused to change its mount type to make it compatible with different camera systems. 
5. Aesthetic & Character: Some vintage lenses have unique optical characteristics that are sought after for particular looks in cinematography. However, their original housing might not be suitable for modern filming needs. Rehousing allows filmmakers to use these lenses with contemporary equipment and techniques.

In essence, rehousing offers a bridge between the visual characteristics of a lens and the practical needs of today’s photographers and filmmakers.