Just recently I managed to get my hands on a Sigma 50mm f/2.8 Macro for a very reasonable price. This macro is a manual focus lens with the A setting on the aperture ring which according to Sigma first came out in 1990 and was the first generation of their line of 50mm macro lenses. The Sigma is a dedicated macro lens that goes to 1:1 magnification without the need of any extension tube or close-up diopter, similar to my auto focus Pentax FA 50mm f/2.8 Macro. A compact and light lens, it comes with a screw-in lens hood.
My interest in this lens was stirred because I once had the Pentax A 50mm f/2.8 Macro, another fine manual focus macro that like many macro lenses then only goes to 1:2 magnification. For life size magnification, an additional extension tube or a close-up lens was needed. Secondly I also have a similar manual focus Sigma macro lens in the Sigma 90mm f/2.8 Macro.
In the short time I have used this lens, it has given me very nice images with very nice colour and sharpness. The focusing ring is wide and smooth and being able to focus all the way to 1:1 magnification certainly gives it an edge over the Pentax A 50mm f/2.8 Macro. Focusing manually is not a handicap and certainly at the macro range, is much preferred. On balance this is one lens I can highly recommend and for the price I paid, definitely a bargain.
When comparing the two manual focus Sigma macro lenses, the Sigma 50mm macro is almost similar in size and weight with it's 90mm macro counterpart. Both lenses use a wide rubberised focusing ring and about the only complaint I have is the silk-screened distance and magnification markings look like it can be rubbed off over time.
50mm on the left, the 90mm on the rightFrom the front both lenses are about identical in diameter and share a common 52mm filter thread. When extended to their maximum magnification, the 50mm macro (1:1) extends a little longer than the 90mm macro (1:2). In order to reach 1:1 for the 90mm, a screw-in diopter is provided which in practice can be a little fiddly to use in the field. Nonetheless, the 90mm macro makes for a very compact lens for the focal length and is great for portraits.
Almost identical from the frontThe Sigma 50mm macro uses a screw-in plastic hood while the Sigma 90mm macro uses a deeper bayonet type hood that is flocked internally. There isn't much information available on the internet regarding the manual focus Sigma macro lenses (there is also a Sigma 180mm f/5.6 macro that goes to 1:2) but suffice to say I'm happy with the image quality from the two that I have. Bokeh from both lenses are generally pleasing and the out of focus transitions is smooth.
Fully extended at maximum magnificationAll shots of the Sigma lenses were taken with the K20D with the FA 50mm f/2.8 Macro.
