A relative bargain (at least for Pros and serious amateurs), this very well-made lens combines sharp closeup performance and excellent mechanics.
Popular Photography, December 2000

Taking picture of small animals and insects can be difficult, because they often run or fly away, or can be dangerous or become aggressive if you approach them. Therefore it is advantageous to have a greater working distance between the camera and such subjects. Longer focal length lens can provide this greater distance, but most long lens do not focus close enough to provide a large image of small subjects. The tele-macro type lens solves this problem by producing a large, high quality image, up to life-size, while maintaining a long working distance. This can enable you to capture on film the world of photomicrography, without disturbing the subjects. The 180mm F3.5 APO MACRO lens has a very narrow field of view, and can allow very narrow depth-of-field for selective focus and less distracting backgrounds. This lens is most desirable for photographers who are serious about producing high quality images both of macro subjects at life-size reproduction, as well as normal telephotography.

Floating Inner Focusing System

The Floating Inner Focus System of the APO MACRO 180mm F3.5 EX HSM provides high quality optical performance and superior handling and stability. This system moves two lens groups within the lens, so the lens’ physical length remains unchanged. This technique also maintains good correction for Spherical Aberration and Astigmatism, and provides extremely high optical performance from infinity to 1:1 Macro.

Full-time Manual Focus with HSM

Macro photography requires precise focus adjustment. The HSM (Hyper Sonic Motor) feature is ideal for this purpose as it allows quick and precise manual focus, even in auto focus mode. Simply focus with HSM auto focus, then while partially depressing the shutter release, turn the manual focus ring until any desired focus adjustment is made. Then depress the shutter release fully to take the picture. It is not necessary to switch from AF to MF. When the shutter release is next depressed, the AF function will resume. Of course the AF function can be disabled altogether, and only MF used, if desired.

It is possible to use 1.4x or 2x Sigma Apo Tele Converters.

Macro photography can be further enhanced by the 1.4x APO EX tele-converter, which allows the photographer to use the new SIGMA APO 180mm F3.5 MACRO lens as a 252mm F5 lens while maintaining auto focus function from infinity to 1.2m(47.2 in.) with Canon, Nikon and Sigma cameras. At distances closer than 1.2m (47.2 in.) the lens automatically switches to MF mode. When this lens and the 1.4x EX tele-converter are used with Minolta or Pentax cameras the lens must be focused manually. When used with the 2x EX tele-converter, the 180mm F3.5 lens becomes a 360mm F7 lens with manual focus function only, regardless of camera mount.

Use of SLD (Special Low Dispersion) glass

Image quality depends in part on color Aberration, which occurs due to differences in the wavelength (color) of light, causing the different colors to focus at different planes. SLD glass in the front optical group helps compensate for this phenomenon, and enables the lens to deliver images of high optical quality, having outstanding crispness and sharpness.

Inner Focus

Inner focusing improves handling and focus operation from infinity to close-up, by keeping the lens’ length constant. It also allows easy handling and use of circular polarizing filters, as the front barrel does not rotate during focusing. The large grippable manual focus control ring is ideal for manual focus photography. This lens also features a Focus Limiter Switch, to provide quicker AF function.