Cinema or Still

With the evolution of the digital video camera and the emersion of interchangeable lens video cameras, videographers have been stuck with using lenses designed for still photography, because of the more affordable price point of still lenses. Cinema lenses are a virtually unknown for many shooters. 

 

 

The market for videocentric lenses has grown in recent years, and affordable cinema lenses are now available. Because of this, a good understanding of what makes a cinema lens different from a still lens is needed. We’ll be addressing the differences between cinema and still lenses. 

 

 

Here are many differences between still and cinema lenses, but lets start with their physical attributes. Cinema lenses are designed with focus marks on the side of the lens, so they can be seen by a dedicated  focus puller. On photo lenses focus marks are harder to read because they are not placed as easy to see from the side of the camera for the us of the focus puller. As well with cinema lenses, the focus ring has hard stops, so the relation to the focus marks don't change, where as many photo lenses have continuous movement past the furthest and nearest focus.

 

 

Optically and mechanically cinema lenses are engineered differently because they are made for video. Optical aberration and distortion are for the most part far reduced on cinema lenses. They are designed with precision as the utmost importance. Focus, aperture and zoom are all manually adjusted with rings, not motors. The focus ring has much larger degree of smooth rotation, even as much as 300 degrees. This creates precise, silent and smooth focus operation. As well cine lenses are geared with an 0.8 Pitch gearing for use with a follow focus.

 

 

A cinema lenses iris is measured in t stops. We’ll have more about t-stops in just a few minutes.  The aperture ring is de-clicked for smooth changes and the glass is typically larger. The glass usually has coating to improve light transmission and reduce vignetting however all lenses have some vignetting. 

 

 

Cinema lens colors and bokehs match if from the same manufacturer, their outer diameter is exactly the same for filters and matte boxes in the case of zeiss lenses. 

And lastly, cinema lenses will have the closest color-matched sets available.

 

 

The focus throw is the distance the focus ring on a lens travels from the closest point of focus to infinity. With a longer focus throw it takes more turning to get through the full range of focus. But it’s preferable when there is a dedicated focus puller increasing the chances of hitting focus marks accurately. Short focus throws can lead to more errors because a small turn will change the focus drastically.

 

 

The answer to the negatives from both long and short is having a dedicated focus puller. The operator doesn't have to turn the lens as much keeping the camera more stable.

 

 

If a dedicated focus puller isn't an option,  a small follow focus gear drive together with a larger lens gear to expand the lens's diameter will result in the focus throw being longer/slower and more precise.

 

 

Because still lenses are designed with photo in mind and cinema lenses for video, the small adjustments that make a world of difference in video, just isn't possible with a still lenses. Still lenses give you aperture adjustments in ? stop increments, whereas cinema lenses offer finer adjustments in ? stop increments. As well, some cinema lenses offer smooth motion through the stops, verses steps up and down in aperture with a still lens. Lastly, one of the biggest negatives of still lens aperture control is variable maximum aperture over the zoom of the lens. There are photo lenses that offer the same max aperture through the zoom, but many offer a variable max over the same zooming distance. Not a huge setback in photography but can change everything when shooting video when you need to zoom in or out without changing the aperture. 

 

 

To make room for autofocus motors and be able to make the lens for less money, the internal parts of a still lens tend to be less precise. Because of this, there is no focus hold when zooming. On camcorders, its typical practice to zoom in, focus and zoom back to the desired framing. However with photo lenses, it's best to use the in camera digital zoom to get close to the subject to be able to have precise focus for best sharpness. This process is needed because still lenses don’t hold focus through the zoom of the lens. 

 

 

The t in t stop stands for transmission. The t-stop is the actual amount of light that makes it to the sensor. Where as f stop is a guide, based on formula and does not account for light lost when transmitted through the glass of the lens. This is why the t stop number and the f stop number can be different. As well, the t-stop number is more accurate of a measurement, making it an advantage over still lenses.  

 

 

No matter if you are using a still lens or a cinema lens, knowing what each can and can not do will make choosing between the two a simpler proposition.