Arri Ultra Prime 20MM / T1.9 - PL

Listing description

ARRI K2.47325.0 (K2473250) Carl Zeiss Distagon 20mm / T1.9 imperial (feet) scale 35mm ULTRA PRIME lens with PL mount / 95mm front OD

New optical standard for cinematography
Based on the latest in design methods, optical glass, and findings on suppression of reflexes and stray light Carl Zeiss and its partner ARRI have introduced a new generation of fast prime lenses for 35 mm film, the Ultra Primes.

Ultra Prime lenses come with large, easy to read calibrated scales, uniform diameters and position of focus and aperture drive rings, and uniform position of exit pupil. Ultra Prime lenses are particularly robust and easy to service. The optical performance is superb, even wide open. Floating elements keep the optical performanc up all the way to the close-focusing limit. Distortion is well controlled and so is breathing, especially with the wider angle lenses, where it counts most.

The Zeiss/ARRI Ultra Primes currently are the largest set of cine prime lenses. And Carl Zeiss and ARRI are already working to add to it further.

New Optics

Floating Elements for outstanding close-up performance Lenses reach their highest performance at the focus setting for which they have been optimized. This is normally infinity.

Beneath that the performance usually drops off, particularly through a considerable increase in image area curvature and increasing aperture aberrations. Because of this, most optics manufacturers limit the minimum close-up setting possibility of their lenses to avoid users from moving too far into this area of lesser performance.

With the ULTRA PRIME lenses, Carl Zeiss introduced and perfected an effective means against: Floating Elements. This is a design principle in which lens groups move in relation to each other during focusing, thereby correcting image area curvature. This principle must be taken into account not only in the optical design but also in the highly precise construction of the mechanical components. Both were achieved for the new ULTRA PRIME lenses allowing for close-up setting possibilities almost up to the front element of these lenses.

Genuine Internal Focus

For sensitive focusing at a constant optical length Conventional lenses change the distance of the entire internal optical assembly relative to the filmplane when focusing.

In practice this brings considerable disadvantages, for example through drift of the gears for focus and iris, displacement of the center of gravity, etc.. All these disadvantages are avoided by the ULTRA PRIME lenses: through their genuine internal focus, the external position of the lens remains constant for the entire range of focus. Instead of moving the entire internal optical assembly with a large drive mechanism, only small lightweight lens groups in the interior of the lens are moved. This facilitates considerably more sensitive focusing.

Increased image contrast according to the latest research findings of Carl Zeiss In response to the extreme demands of advertising photography, for which Carl Zeiss is one of the leading optics suppliers, new methods and materials were developed to suppress stray light and to increase colour saturation. Purer, more intensive colours, especially at full aperture, were thereby achieved.

An important criterion in the optical design was a high MTF value for the rendering of 10 line pairs/mm, a frequency range which is responsible especially for the crispness of the image. On all ULTRA PRIMES over 90 % MTF was attained for this spatial frequency. The extremely uniform brightness across the entire image area augments the impression of sharpness. Colour fringing is no longer perceivable. For the first time the ultra primes unlike other lenses were corrected not only for infinity, but also particularly for close-focus. The result: highest quality optical performance over the entire focus range.

Unified Colour Characteristics: Super-Colour-Matched It goes without saying that the optical glasses were especially selected to ensure unified colour characteristics. As the inventor of optical anti-reflex coating, Carl Zeiss however augments this with a T* multiple-layer anti-reflex coating system for individual lens surfaces, which is adapted so that the colour characteristics (Color Contribution Indices) of all lenses of the entire set lie close together with very narrow tolerances. Put simply: the ULTRA PRIME lenses are super colour-matched.

Superior mechanics

Precision focusing with constant optical length, without backlash.

All lenses in this set have a rigid, very robust housing. The overall length is constant over the entire focusing range. The completely new focus drive mechanics are particularly sensitive and free of backlash.

Iris and Focusing Rings without axial displacement
The rigid construction creates the prerequisite for an important advantage: the position of the gears for focus and iris does not move axially during focusing. External motor units thereby work more simply and with considerably increased reliability. Also, lens changing becomes much easier, faster and safer.

Nine-bladed and ten-bladed irises
The iris on the ULTRA PRIME lenses is a new design and practically free of hysteresis error. The 135mm focal length employs a ten-bladed construction, the other focal lengths a nine-bladed design. The contours of the aperture are better rounded, and the depiction of unsharp light sources on the film thereby more round than angular - i.e. more "natural" and aesthetic than "technical".

This equipment is located in GB