The Lens/Focus Shifter is a low budget 'follow focus' product which attaches to lenses with circumferences from 176mm to 308mm, or lenses like the 50mm f/1.8 to the larger zoom lenses. The great thing about this product is that it attaches to these lenses without the need of rails, with the simple attachment mechanism it simply slides onto any size lens, making it a very flexible, low priced and innovative product. Using this product will definitely improve focusing skills for photography and cinematography, as critical focus points can be pre-focused and marked with the marker pen to ensure the focus puller/camera operator reaches those critical focus points during filming or taking photos.
It's currently available for $45 on Kickstarter:
