What's in a Name? Sigma Lens Labeling

1. How Sigma Lenses Work

The Sigma lens lineup is filled with a wide variety of options for every occasion—from all-seeing fisheye lenses to massive telephoto "cannons" that not every tripod can support. Moreover, most lenses are produced for all common DSLR mounts and some mirrorless systems. The brand's lenses stand out due to their attractive price, outstanding optical qualities, and models with unique focal lengths that are hard to find anywhere else.

Let’s start deciphering the abbreviations in the names of Sigma lenses by dividing the lenses into separate categories:

C (Contemporary) — a line of budget lenses with standard optical properties designed for amateur-level photography.

A (often Art) — high-class optics designed with a focus on advanced optical performance. Art lenses often feature high aperture values, and their full potential is revealed in creative photography.

S (Sport) — a professional line of lenses for capturing sporting events, wildlife, and other similar scenes. The "S" symbol is printed on the body of telephoto lenses (long-focus lenses for shooting from a distance).

EX (Excellence) — this somewhat bold abbreviation indicates the outstanding optical qualities of a lens (similar to the gold ring on Nikon lenses and the L (Luxury) series on Canon lenses). This labeling has since been discontinued, and all top lenses released after 2012 belong to the Art and Sport lines.

The distinguishing feature of the EX premium lens line was always the gold ring on the front element

Individual symbols also denote the compatibility of a lens with specific camera types:

DG — optics for full-frame DSLRs (also work well with APS-C format cameras).

DC — lenses for cropped DSLRs (cameras with sensors that are 1.5-1.6 times smaller—APS-C format).

DN (Digital Neo) — the latest lens family designed for use with mirrorless cameras. Existing models are compatible with cropped cameras, but future full-frame mirrorless lenses may receive a new index.

Some of the most important combinations in lens names are as follows:

105mm, 18-35mm — standard focal length designations. A single value is used for primes, while a pair of numbers separated by a hyphen indicates a zoom lens.

f/1.8, f/3.5-6.3 — the maximum aperture of the lens. When multiple numbers are separated by a hyphen, the first value is the maximum aperture at the short end, while the second is the aperture value at the maximum zoom setting.

Following the key focal length and maximum aperture designations, additional abbreviations are included in the lens name:

IF (Inter Focus) — internal focusing system. When focusing, all optical elements move inside the body, which itself does not change in physical size.

RF (Rear Focus) — similar to IF, but only the rear group of elements moves during focusing.

HSM (Hyper-Sonic Motor) — an ultrasonic motor for autofocus, providing fast, accurate, and almost silent focus for both photo and video shooting. It also has low power consumption, helping save camera battery life.

The highlighted combination of symbols indicates that the lens is equipped with a fast and quiet ultrasonic autofocus drive

OS (Optical Stabilizer) — indicates the presence of an optical image stabilization system, designed to compensate for camera shake and allowing for a few extra stops of exposure when shooting handheld in low-light conditions. For more on how optical stabilization works, check out the article "All You Need to Know About Image Stabilization Systems".

APO (Apochromatic) — inclusion of apochromatic lenses made from low-dispersion glass to minimize chromatic and other aberrations. These elements are found in some telephoto lenses from the Japanese manufacturer (e.g., Sigma 70-200mm f/2.8 EX DG APO OS HSM).

APO elements are the prerogative of "long-range" optics

ASP (Aspherical) — aspherical lenses in the optical design to combat chromatic aberrations and improve image quality. Their use also helps reduce the weight and size of the lens.

SLD (Special Low Dispersion) — low-dispersion lenses to minimize chromatic aberrations.

ELD (Extraordinary Low Dispersion) — an even more effective subtype of low-dispersion lenses.

FLD ("F" Low Dispersion) — the lowest level of low-dispersion glass with exceptionally high light transmission.

TSC (Thermally Stable Composite) — a special material used in some lenses, combining the properties of metal and polycarbonate. An example of such a solution is the universal zoom lens Sigma 18-250mm f/3.5-6.3 DC Macro OS HSM.

UC (Ultra Compact) — a compact version of the lens with similar optical characteristics to the "big brother".

Mini version of a universal zoom with a 28-105mm focal length range

The list of abbreviations concludes with a few special labels:

Macro — no need to guess—lenses with this designation are intended for macro photography. However, not all lenses labeled "Macro" provide 1:1 magnification. Sigma has previously overused this labeling, applying it to lenses with a reduced minimum focusing distance.

Diagonal Fisheye, Circular Fisheye — types of fisheye lenses with very wide angles of view (around 180°).

The front element of fisheye lenses has a distinctive convex shape

II, III — indicates the version of the lens when an existing model is re-released in a new form while retaining its original labeling.

Happy shooting!