Figure

• Lens body

  Machined metal

  From exterior parts to inner structural parts, on which the operation ring slides, the I series is produced from the machining of metallic materials. It has a luxurious construction very similar to the SIGMA CINE LENSES range, which is designed to withstand heavy use by professional image-makers.
  Chiefly using robust metallic materials that can make the lens much more durable, and no alternative material can offer the same feeling of solidity and weight, or such a stylish look and feel.

• Hood, operation ring

  Elaborate knurling

  A large number of grooves called ‘knurling’ are cut into the hood, the focus ring and the aperture ring, improving the lens operation by serving as slip resistance and giving the lens a premium look and feel unique to the I series.
  All the grooves are cut one by one, a meticulous process that ensures a luxurious finish.

• Lens body surface

  Leading surface treatment technique

  On the exterior of the metal barrel, a matting treatment called blast, in which particles are blown onto the surface, is applied. Also a treatment called alumite, in which an oxide film is produced on the surface to make it black, is added.
  A combination of these two treatments create a unique gloss and texture. As I series lenses have metal parts lying next to each other, a high level of quality control is required to prevent a difference in the finish between adjacent parts. This is achieved using the know-how obtained through the manufacture of SIGMA CINE LENSES.

• Processing accuracy

  The matched surfaces are proof of the processing accuracy.

  The part on which the scale of the aperture ring is engraved and the part on which the base line and the product name are engraved have the same diameter, naturally connecting the two adjacent parts on the plane of the same height.
  This connection on the plane also constitutes extreme precision of manufacture specific to the I series. Any deviation that occurs in part processing can lead to a gap, which creates a difference in level, or a slight protrusion, when the parts are put together as a lens.
  The matched surfaces are the proofs of the processing accuracy. Please trace this part with your finger and feel a natural connection.

  

• Aperture ring

  Precise, reassuring action

  The aperture ring offers a precise, definite action, with great attention paid to ensure the click is well-defined but not too sharp. Sound-deadening grease is used to create a more rounded sound.The touch that one feels when the operation ring hits the edge was crafted so that it can produce the right strike feeling

• Focus ring

  Construction without compromise

  The focus rings of the I series lenses have fluid-like, well-damped movement. They are very smooth when they begin to move, and then offer the right amount of resistance owing to the viscosity of the grease used in their construction.
  The realization of this movement was made possible owing to the extreme engineering precision of both external and internal structural parts. The near-perfect roundness of the focus ring was achieved by a sophisticated metal processing technique at the SIGMA Aizu factory that aids very fine adjustment. The precision of the focus ring movement demonstrates our exceptional attention to detail in the design, manufacture and assembly of these lenses.

• Focus mode switch

  Tactile and intuitive switch action

  A newly-developed dedicated long-stroke switch has been adopted to change the focus mode on the 20mm F2 DG DN | Contemporary, 24mm F2 DG DN | Contemporary, 35mm F2 DG DN | Contemporary, and the 65mm F2 DG DN | Contemporary. To create a solid click action when the switch is shifted, it incorporates an intricate mechanism including a spring, a steel ball, and a dedicated press part.
  However, adopting these mechanisms increased the switching speed, which presented two drawbacks: a sharper action and increased sound. To improve these, a mechanism for enclosing sound-deadening grease in the switch unit was added, helping reduce the operational sound.

  

• Operational feeling

  The greatest operational feeling born from the latest technology

  In the development of the I series, meticulous attention was paid to the touch and feel of the operational parts, which might remind some users of their experience of using classic, pre-digital lenses.
  But unlike on these older, classic lenses, on which the operational parts were mechanically connected to the inner structure, the I series, which is designed exclusively for mirrorless cameras, works in a different way, bringing a range of advantages. The focus ring adopts a by-wire system, while the aperture ring is operated electronically. In other words, it is possible to achieve the perfect operational movement without being restricted by the inner structure, as the two are not mechanically linked.
  This latest technology allows the best experience when using these lenses, and is another reason that the I series was born from the Contemporary line.

• Cover ring

  F2 icon that improves operation

  A cover ring is used between the focus ring and the aperture ring on the 20mm F2 DG DN | Contemporary, 24mm F2 DG DN | Contemporary,35mm F2 DG DN | Contemporary and the 65mm F2 DG DN | Contemporary.
  This is the position where the fingers naturally sit and it enables easy attachment and removal of the lens from the camera. In addition, the tactile finish of the surface is a combination of the trajectory of a cutting blade and alumite layer. This is adopted in parts of the Art lens mount as well, which delivers a brushed finish that represents the iconic design of the lens body.

• Assembly

  Lenses adjusted one by one

  In the I series, all letters and lines are engraved by lasers, which are able to create extremely fine lines compared with preprint, and there is no risk of peeling, which can occur with ink. However, having fine lines means having a thin scale and baseline, which makes gaps more noticeable when the parts are assembled. For this reason earlier SIGMA lenses did not have the scale mark on the aperture ring.
  In the I series, to properly align the scale of the aperture ring to the base line, lenses are visually checked and assembled one by one without creating a guide for assembly in the part.

• Magnetic metal lens cap

  Meticulously crafted dedicated cap

  The 24mm F2 DG DN | Contemporary, 24mm F3.5 DG DN | Contemporary, 35mm F2 DG DN | Contemporary, 65mm F2 DG DN | Contemporary and the 90mm F2.8 DG DN | Contemporary of the I series are accompanied by a dedicated magnetic metal lens cap, in addition to a normal plastic cap. This dedicated metal cap clips to the front surface of the lens magnetically. It is no exaggeration to say that this meticulously crafted cap represents the finishing touch for the I series.
  SIGMA I series | Magnetic Metal lens Cap Promotion Video

  *Cannot be used when a filter is attached.

  

• Magnetic metal lens cap holder

  Cap holder created for added convenience and style

  When a cap is removed from the lens it should have a proper place where it can be kept. Using this as a starting point, a cap holder using the magnetic force of the dedicated cap was created.
  With the cap attached to the ring plate, and the plate clipped to a bag or belt, the cap is always within easy reach and is less likely to get lost. Plus, its elegant design is a stylish addition to a photographer’s equipment.

  

• Dedicated metal hood

  Materials carefully selected for the highest quality and usability

  On the dedicated metal hood, the bayonet section was made of plastic with the goal of obtaining a smooth and secure attachment to the lens. Since a metal and a plastic part rub directly against each other, a special plastic material was adopted to improve durability and smoothness. It achieves both sturdiness and elegance, which makes the I series unique.
  As with the main body, all of the sections except the sliding section adopt metallic materials and are molded through machining. The hood requires a totally different cutting pattern for the inside and the outside. Grooves called knurling are engraved on the outside, while notched level differences called light shielding lines are engraved on the inside. These are created one-by-one through an intricate process.