|Sony Alpha Macro and teleconverter lenses
Macro lenses are designed for photographing small subjects at close range, such as flowers or insects. All lenses can take close-up photos, but Macro lenses are optimised for it, and are able to produce much better results.
Typical macro lenses have focal lengths between 50 and 100mm and can also be used for other subjects, although they are designed to perform best at close range.
Remember to take your camera's field-reduction factor into consideration. Sony's APS-C models like the A100, A200, A300, A350 and A700 have a field-reduction factor of 1.5x which means all lenses have their focal length effectively multiplied by 1.5 times - so the 50mm Macro lens will deliver an equivalent field of view of 75mm. Note the DT 30mm f/2.8 SAM Macro is not compatible with full-frame bodies.
Teleconverters are compact units which fit between a lens and camera body to multiply the focal length. A 2x teleconverter will multiply a lens focal length by two times, allowing, say, a 200mm lens to deliver the same field of view as a 400mm. This saves you from buying or carrying two lenses.
Teleconverters can work with almost all lenses, but are designed to work best with telephotos. Note a handful of lenses may not be compatible with teleconverters, so check before buying.
The downside to teleconverters is a slower focal ratio. If you use a 2x teleconverter, both your focal length and your smallest f-number will double. So if you had a 300mm f2.8 lens, it would become a 600mm f5.6 lens. This represents two stops difference, which means an exposure four times slower. A slower focal ratio can also cause problems for some autofocus systems which tend to only work at f5.6 or brighter. So if you use a 2x teleconverter on an f5.6 lens, it will become an f11.2 model with manual focus only.
Sony offers a 2x and a 1.4x teleconverter. The 1.4x model clearly won’t extend the focal length as much, but only results in the loss of one stop – so you’ll only need an exposure twice as long. A 300mm f2.8 lens with a 1.4x teleconverter would therefore act like a 420mm f4 model.
For a full explanation of lens specifications and examples of coverage at different focal lengths, check out our Camera Labs Lens Buyers Guide.