OM System M.Zuiko Digital 45mm f/1.8

This OM System prime fits Micro Four Thirds cameras. At 45mm it works as a short telephoto on the format, which makes it a natural portrait length. Candid people pictures, family gatherings and quiet event work suit it as well. You can also use it for detail shots at events, such as table settings or flowers.

The main trade-off is the fixed focal length. You frame by stepping closer or further back rather than zooming. That suits photographers who own a zoom already and want a small, light portrait prime.

The lens weighs 4.1 oz (116 g) and measures 2.2 in (56 mm) across, so it is a very small and light lens. The front thread accepts 37mm filters, and a screw-in filter must match that 37mm thread to attach directly. It scores 64 out of 100 here for physical specification.

The 45mm focal length gives a short telephoto view on Micro Four Thirds. It suits portraits, candid people pictures and details at events. Framing depends on subject distance. Step back to include more of a person or setting; move closer for a more prominent subject. Check that the room gives you enough space.

The f/1.8 maximum aperture is bright. It passes more light to the sensor than a smaller opening would. In dim rooms or evening streets, that lets you set a faster shutter speed in the same light. At close portrait distances the zone of sharpness can be shallow, so focus placement matters.

At its widest opening, the lens can soften a background behind a portrait subject. The result depends on the distance between the camera, subject and background. A more distant background can help separate the person from a busy street or cluttered room. Check focus carefully on the face.

Closest focus is 1.6 ft (50 cm), measured from the sensor. This is the minimum separation for nearby objects. Leave room ahead of the front glass and avoid shading a small subject. The optics specification score is 81 out of 100.

There is no stabilisation in the lens. A camera with body stabilisation can reduce shake for still scenes. Firm support helps with slow exposures. For people moving at an event, use enough shutter speed for their movement as well as your own.

There is no weather sealing. Use cover in rain and keep the lens away from blowing dust or sea spray. Keep the mount clean when changing lenses outdoors.

Keep the front glass protected during transport. Remove loose dust before wiping marks, especially after work near sand or soil. A cap helps stop dirt reaching the glass when the lens is stored.

Nine elements in eight groups form the optical path. Focusing is internal, so elements move within the barrel and the lens keeps a constant length as you focus. This helps keep space ahead of the lens predictable when working near a small subject. The construction specification score is 23 out of 100.