Sigma 70-300mm f/4-5.6 APO DG Macro
This inexpensive and lightweight lens (for the zoom range) from Sigma exists in two almost identical versions. Its slightly cheaper brother does not have the two extra SLD (special low dispersion) glass elements in the front group that makes this version slightly better optically. You can tell the two apart visually by the APO-version having a red stripe around the forward part of the lens barrel.
As indicated by the price, this lens is in the consumer segment. However, for the price performance is fair, but not excellent. Stopping down improves things, and the lens is at its sharpest at f/11. Optical performance is distinctly better at the wide end. When you extend the zoom beyond 200 mm, things go downhill fast. At 300 mm the corner resolution is pretty sad. As is often the case with Sigma, centre resolution is much better throughout the range. But if you want sharp corners, this is not the lens to get.
CA is well controlled at the wide end. At the tele end, CA is quite visible. Distortion is low at the wide end, with just a hint of pincushion distortion at the tele end. Vignetting is pretty bad on FX. On DX, however, vignetting is minimal.
Normally, the lens has a min. focus distance of 150 mm, where the magnification is 1:4. However, once the lens is extended past 200mm, there is a sliding switch that enables “macro” mode. This allows the focus ring to travel further. In this mode, maximum magnification is half life size.
Mechanically the lens is clearly consumer grade. It is made mainly of plastic, but the mount is metal. The front element rotates during focusing. The autofocus is slow and noisy.
Given its very low price, this lens is not a bad buy. But given its lack of corner sharpness and the visible vignetting on FX, this lens is probably better suited for a DX body.
Rating: Ed: -, User: - (normalized, 0=useless, 50=average, 100=excellent).
Mounts: Canon EF, Nikon F, Pentax K, Sigma SD, Sony A.
Aperture range: f/4-5.6 to f/32.
Optical zoom: 4.3x.
Close focus distance (CFD): 95 cm / 3.12 ft (from sensor plane).
CFD magnification: 1:2 / 0.5X.
Focus: AF (built-in, gear-type).
Filter diameter: 58 mm (rear).
L x D, W: 120 x 78 mm, 530 g.
Approximate street price: USD 209 (new, w/o tax).
Introduced: no data.
Sigma is a family owned manufacturer of photographic equipment founded in 1961 in Japan. The company's main business is to manufacture third party lenses. However they also produce third party flash units and, since 2002, their own line of DSLR and compact cameras. Sigma's digital cameras use a special sensor, developed by Foveon, that records full color information for every pixel. In late 2008 Sigma acquired Foveon.