Tamron 90mm f2.8 Macro is a very sharp lens with 1:1 macro capability. It is one of the sharpest lens in its class. I have had the lens for over 3 years and compared its optical performance with different lens, including some Nikons professional range lens. The lens is always among the top few in sharpness. 90mm focus length is quite useful for both portrait and macro photography. There is almost no distortion which is perfect for portrait. The build quality is very good for the money with smooth operation of focus ring and easy push pull switch between AF and MF mode. The sharpness maintains well throughout the most of aperture settings except at extremes. f2.8 is quite useful at low light but it is the other end that is more useful for macro photography. It can step down to f32 which can be useful if you want to get enough depth of field in macro mode, although with reduced sharpness. It is quite compact and light weight. Although there is lens hood come with it, I rarely use it as the front element of the lens sits far back inside the barrel. The AF is slow compare with lens with built-in motors, which is about all I can complain about this lens. It is a very sharp lens ideal for portrait and macro photography with a very reasonable price tag. I would recommend it to any one who think that sharpness is the most important factor for lens. It may not suit you that well if the built quality or AS speed is more important to you.
The SP90mm 1: 1 macro lens retains the outstanding optical quality provided by the highly rated Tamron SP90mm it succeeds. With emphasis on portability, the lens is now considerably smaller and lighter, measuring 97mm in length and weighing only 403g. It boasts high resolving power and sharp image depiction with ideal background blur. The lens has a new focusing ring clutch, which engages and disengages the focusing gear. Now the switch between AF and MF is a simple slide of the focusing ring forward or back. This mechanism and a wide, smooth focusing ring make delicate manual focusing in the macro mode easy and precise.