Cinema Lenses vs Still (Photo) Lenses
What's the difference?
The difference between cinema and still lenses is nothing obvious when it comes to price. Cinema lenses can cost anywhere from a few thousand dollars (usually cheaper quality) to as much as tens-of-thousands of dollars (about average), or even more. Whereas still lenses can be as cheap as under $100 to a few hundred at most. So why the price difference?
Build quality. Cinema lenses are more durable, though heavier than their counterparts. Majority of cine lenses are metal built (great for use in various weather conditions) compared to majority of still lenses that are in a plastic housing. Cine lenses also have all the perks of manual focus, zoom, and aperture rings. Most still lenses usually just have a focus ring, or zoom for zoom lenses, but no manual aperture adjustments.
Focus. One of the best features of cinema lenses is their ability to maintain focus and smoothly refocus. This is because cinema lenses have hard stops, which still lenses do not. This allows less "focus breathing" and buttery smooth transitions. Cine lenses are also parfocal lenses, meaning that they keep subjects in focus whether zooming in our out of a scene.
T-stops. T-stop markings on cine lenses, compared to f-stops on still lenses, give the exact measurement of light allowed through then lens. Where f-stop lenses just measure how wide the lens opens.
Below is a chart to further compare the difference between the two lenses.