Sigma has today announced two new lenses for Sony and Pentax cameras.

The 50-150mm f/2.8 EX DC HSM II is a compact, large aperture telephoto zoom lens.

This large aperture telephoto zoom lens is designed to match APS-C size image sensors.

It delivers a minimum focusing distance of 100cm, a large aperture of f/2.8 and a large depth of field.

Four SLD glass elements are used to correct chromatic aberrations, while the lenses' super multi-layer lens coating reduces flare and ghosting.

The lens design incorporates an inner focusing and inner zooming system, so that the overall length of the lens does not change during focusing and zooming.

The HSM (Hyper Sonic Motor) system allows quiet and high-speed auto focusing with full time manual focus override by rotating the focusing ring.

The addition of the optional 1.4x EX DG APO or 2x EX DG APO Tele Converters produce a 70-210mm F4 AF tele-zoom lens and a 100-300mm F5.6 AF ultra-telephoto zoom lens respectively.

The 50-150mm lens is priced £549.99, while the second launch, the 70-200mm f/2.8 II EX DG HSM will set you back £799.99.

This large aperture zoom lens has a minimum focusing distance of 100cm and maximum magnification ration of 1:3.5.

It is built around two SLD (Special Low Dispersion) glass elements which correct all types of chromatic aberrations.

The lens also incorporates a Hyper Sonic Motor (HSM) which ensures high speed autofocus.

Alike the 50-150mm lens, the 70-200mm optic also incorporates an inner focusing and inner zooming system, so that the overall length of the lens does not change during focusing and zooming.

A removable tripod collar is included.

Key features at a glance of the 50-150mm lens:
- Minimum aperture: f/22
- Minimum focusing distance: 100cm
- Maximum magnification: 1:5.3
- Filter size: 67mm
- Lens construction: 18 elements in 14 groups
- Weight: 780g
- Dimensions: 76.5(D)x140.2mm(L)

Key features at a glance of the 70-200mm lens:
- Minimum aperture: f/22
- Minimum focusing distance: 100cm
- Maximum magnification: 1:3.5
- Filter size: 77mm
- Lens construction: 18 elements in 15 groups
- Weight: 1370g
- Dimensions: 86.5(D)x184.4mm(L)