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 — meaning even manual focus is achieved via an electronic 'focus-by-wire' system.

Olympus divides its Zuiko Digital range into three tiers of features, build quality and price.

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-1's successor they will provide the world's fastest autofocus system in their class.

Super high grade lenses

All the lenses in this series are dust- and moisture-sealed, and expensive.

• Zuiko Digital ED 7–14mm F4
• Zuiko Digital ED 14–35mm F2 SWD — Planned for release some time in 2008
• Zuiko Digital ED 35/100mm F2
• Zuiko Digital ED 90–250mm F2.8
• Zuiko Digital ED 150mm F2 — With Sigma's 'Hyper-Sonic Motor' autofocus technology.''
• Zuiko Digital ED 300mm F2.8

High grade lenses

All the lenses in this series are dust- and moisture-sealed, have 'focus distance scale' windows on the lens body, are internal focussing, have variable aperture as it 'zooms' and generally are in the 3 or 4x zoom range [the exception being the '2x' 11-22].

• Zuiko Digital ED 8mm F3.5 Fisheye — Produces a full frame image, not vignetted like many 35mm fisheye lenses. With Sigma's 'Hyper-Sonic Motor' autofocus technology. [Sigma lens technology in a Olympus lens needs confirming. Indeed, any sort of untra-sonic motors being in pre-2007 lenses is doubtful and again, needs confirming]
• Zuiko Digital 11–22mm F2.8–3.5
• Zuiko Digital 12–60mm F2.8–4 SWD
• Zuiko Digital 14–54 F2.8–3.5
• Zuiko Digital ED 50mm F2 Macro — Maximum magnification of 1.04× life size
• Zuiko Digital ED 50–200mm F2.8–3.5 — To be replaced by the below 'SWD' verison
• Zuiko Digital ED 50–200mm F2.8–3.5 SWD
• Zuiko Digital 'Telephoto Macro' — This lens is planned for release in 2008, no specifics on focal length as yet but is thought to be around 100mm.

Standard lenses

The lenses in this range are 'consumer grade'; they are not weather-sealed and have lower build quality and optics.

• Zuiko Digital 'Ultra-Wide zoom lens — This lens is planned for release in 2008, no specifics on focal length as yet.
• Zuiko Digital ED 14–42mm F3.5–5.6 – New, lightweight standard kit lens for E-410 etc
• Zuiko Digital ED 18–180mm F3.5–6.3
• Zuiko Digital 35mm F3.5 Macro — Maximum magnification of 2x life size
• Zuiko Digital ED 40–150mm F4–5.6 – New, lightweight telephoto kit lens for E-410 etc
• Zuiko Digital ED 70–300mm F4–5.6 — Planned for release some time in 2007

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 telephoto 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.