Four-Thirds lenses

Owing to the cooperative nature of the Four-Thirds standard, several manufacturers currently produce lenses for it. Whereas a company like Sigma usually produces lenses for another company's cameras without the official blessing of that company — and therefore must design its equipment through reverse-engineering — as it is signed up as a Four-Thirds partner it has access to all the design specifications and technologies as laid out by Olympus in the Four-Thirds white paper. All 4/3rds lenses are fully compatible with other 4/3rds system equipment.

Note: Owing to the size of the Four-Thirds system sensors, the focal lengths of the lenses below should be doubled for their effective focal length equivalents in 24×36mm format.

Olympus Zuiko Digital lenses

All Olympus Zuiko Digital lenses are designed from the ground up to match the 4/3rds image sensor format. Similar to Canon's EOS system they have fully electronic mounts, with no mechanical connections to the camera bodies at all — a side effect of which is that even manual focus is achieved via an electronic 'focus-by-wire' system. Later Zuiko Digital lenses (late 2007 onwards) featuring Olympus' new Supersonic Wave Drive (SWD) motor are eschewing 'focus-by-wire' in favour of traditional focus ring technology.

Olympus divides its Zuiko Digital range into three tiers of features, build quality and price, each tier broadening out the focal length range, i.e.

• Standard: 14mm to 150mm (28-300mm) in 2, F3.5-5.6 lenses.
• High Grade: 11mm to 200mm (22-400mm) in 3, F2.8-3.5 lenses.
• Super High Grade: 7mm to 250mm (14-500mm) in 4, generally 'Constant Aperture' lenses.

All lenses are sold with a lens hood, bag and most of the 'High' and 'Super High' grade lenses come with a tripod bracket.

Terminology

• ED — 'Extra-Low Distortion' elements to minimise refraction and reduce chromatic aberrations
• SWD — In Olympus' second generation of lenses, the 'Supersonic Wave Drive' motors promise almost silent, very fast autofocus. Olympus claim that coupled with the E-3 they will provide 'the world's fastest autofocus system in their class'.

Standard lenses

The lenses in this range are 'consumer grade'; they are not weather-sealed, have lower build quality and smaller, non-constant maximum apertures. However, optical quality is anecdotally considered to be above their price point, as compared to other brands' kit lenses.

• Zuiko Digital 'Ultra-Wide zoom lens — This lens is planned for release in 2008, no specifics on focal length released as yet but rumoured to be a re-badged Sigma 10-20mm f/4-5.6.
• Zuiko Digital 14–45mm F3.5–5.6 - The original standard 'kit' lens with all consumer Olympus cameras from the E-300 onwards. Now discontinued.
• Zuiko Digital ED 14–42mm F3.5–5.6 - New, smaller and lighter standard 'kit' lens for E-410, etc. Has a blue ring around the front element, and a plastic mount.
• Zuiko Digital 17.5–45mm F3.5–5.6 - A 'Special Edition' lens that was released with the E-500 in a SE kit. Now discontinued.
• Zuiko Digital 40–150mm F3.5–4.5 - The original telephoto lens in Olympus 2-lens kits. Now discontinued.
• Zuiko Digital ED 40–150mm F4–5.6 - New, smaller and lighter telephoto kit lens for E-410 & E-510. Slower maximum aperture at all focal lengths the the preceding 40-150mm and a plastic lens mount, though much smaller and lighter than its predecessor.
• Zuiko Digital ED 18–180mm F3.5–6.3 - A 10x 'zoom' thought to be a re-badged and/or re-engineered Sigma 18-200 F3.5–6.3 DC.
• Zuiko Digital ED 70–300mm F4–5.6 - Thought to be a re-badged and/or re-engineered Sigma 70-300mm f/4-5.6 APO DG Macro.
• Zuiko Digital 35mm F3.5 Macro - Maximum magnification of 2x life size; very small and light.

High grade lenses

Of better construction than their 'Standard' tier counterparts, they add dust and moisture-sealing, have a 'Focus Distance Scale' window on the lens body and feature internal focussing. All the 'zoom' lenses in this tier are varifocal and have a variable maximum aperture as the focal length increases. The magnification of these lenses is generally in the 3 to 4x range, the exception being the '2x' 11-22.

• Zuiko Digital ED 8mm F3.5 Fisheye — Produces a full frame, non-circular image.
• Zuiko Digital 11–22mm F2.8–3.5
• Zuiko Digital 12–60mm F2.8–4 SWD - The 'kit' lens with the E-3, the first lens released to feature the new SWD focusing technology.
• Zuiko Digital 14–54 F2.8–3.5 - Released as a 'kit' Lens for the E-1.
• Zuiko Digital ED 50mm F2 Macro — Maximum magnification of 1.04× life size
• Zuiko Digital ED 50–200mm F2.8–3.5 — Supplied with a tripod bracket. Rumoured be replaced by the below 'SWD' version
• Zuiko Digital ED 50–200mm F2.8–3.5 SWD - Supplied with a tripod bracket.
• Zuiko Digital 'Telephoto Macro' — This lens, thought to be around 100mm, is planned for release in 2008.

Super high grade lenses

Of increased construction standard and better optical quality over their 'High Grade' counterparts, these lenses incorporate all that the lower tiers offer while adding 'Focus Limiter' switches and 'Focus Stop' buttons around the foremost focussing ring. With the exception of the 7-14mm and 14-35mm they all come with a removable tripod bracket. All the lenses in this tier are of a constant aperture and all except the 7-14 feature internal focus and internal zoom, which is restricted to 2x or 3x times magnification. On the newer lenses (14-35, 35-100 & 90-250), the lens hoods are lined with a velvet-like material to reduce reflections while incorporating openings for circular polariser use.

• Zuiko Digital ED 7–14mm F4 - Fixed lens hood with no filter thread.
• Zuiko Digital ED 14–35mm F2 SWD - This lens features the new SWD focusing technology, therefore foregoing 'Focus By Wire'. It was over 2 years in gestation and will appear in early 2008.
• Zuiko Digital ED 35/100mm F2
• Zuiko Digital ED 90–250mm F2.8
• Zuiko Digital ED 150mm F2
• Zuiko Digital ED 300mm F2.8 - Has an opening near the mount to accept filters.

Sigma Four-Thirds lenses

The majority of Sigma lenses released for the 4/3rds system are simply adaptations of lenses Sigma previously released for APS-C or 35mm formats.

Terminology

• DC — Lenses marked with this code are designed for digital sensors, and therefore do not have an image circle large enough to suit the full-frame bodies of the system they are mounted for (not a problem for a 4/3rds CCD).
• DG — Lenses with imaging circles large enough to fit 35mm sensors/film (again, not a problem for a 4/3rds CCD).
• EX — Lenses with a better external finish, reportedly to reflect the superior build and optical quality.
• HSM — 'Hyper-Sonic Motor'; this is effectively Sigma's 2nd generation of quieter, faster autofocus motors (and is also in some Olympus 4/3rds lenses)
• ASP — Lenses with one or more aspherical elements, to minimise distortion and allow smaller, lighter designs.
• APO — Lenses with low-dispersion glass to minimise chromatic aberration.

Standard zoom

• Sigma 18–50mm F2.8 EX DC Macro
• Sigma 18–50mm F3.5–5.6 DC
• Sigma 18–125mm F3.5–5.6 DC

Telephoto zoom

• Sigma APO 50–500mm F4–6.3 EX DG HSM
• Sigma 55–200mm F4–5.6 DC
• Sigma APO 135–400mm F4.5–5.6 DG
• Sigma APO 300–800mm F5.6 EX DG HSM

Macro

• Sigma 105mm F2.8 EX DG Macro
• Sigma APO 150mm F2.8 EX DG HSM Macro

Single focal length

• Sigma 24mm F1.8 EX DG ASP Macro
• Sigma 30mm F1.4 EX DC HSM

Panasonic Four-Thirds lenses

Relative newcomers to the DSLR market, Panasonic (Matsushita) has released one camera body — the DMC-L1 — and two lenses for the 4/3rds system. Its lenses are co-branded with Leica, something it began with its Lumix compact digital cameras — it is understood that these lenses are Leica-designed and Matsushita-built.

Panasonic's lenses are unique among those made expressly for the 4/3rds system in having an aperture ring. When used on a Panasonic or Leica body, the aperture can be adjusted with this ring rather than the camera's buttons or dials.

• 14–50mm F2.8–3.5 Leica D Vario Elmarit ASP Mega OIS — kit lens for the DMC-L1 featuring optical image stabilisation (previously Panasonic used this system in its Lumix series of compact digital cameras).
• 25mm F1.4 Leica D Summilux ASP

Panasonic has also announced the pending release of a 14-150mm zoom lens with OIS.

Conversions to the Four-Thirds mount

The distance between film plane and lens flange of the Four-Thirds system is unusually small, two millimetres less than that of the Konica AR system. This allows enterprising people to adapt older SLR lenses for these cameras.

Lenses with the Konica AR mount can be adapted. The process is destructive — the lens will no longer be usable with a Konica body — but the only parts needed are spacer rings.

Lenses with the Canon FD mount can also be adapted. This similarly renders the lens unusable with a Canon body. It is more complex than conversion of a Konica AR–mount lens, and it also requires the mount of an AR-mount lens.

Adapters for the Four-Thirds mount

Various companies produce adapters that will mate lenses intended for other SLRs with Four-Thirds bodies. For example, there are "RayQual" adapters for the Minolta MD, Nikon F, Olympus OM, Leica R, M42, Contax/Yashica, and Pentax K mounts.

References

• Bergfors, Jörgen. "Konica to Four Thirds Modification". Fourthirdsphoto.com.
• Bergfors, Jörgen. "Hexanon 40, F1.8 to Fourthirds Conversion". Fourthirdsphoto.com.
• Bergfors, Jörgen. "Canon FD to FourThirds Mount Conversion". Fourthirdsphoto.com.