We have been given the opportunity to try 2 versions of the highly regarded Tamron 90mm macro lens side by side, they are the original incarnation (model 52B) known as Adaptall 2, which is manual focus and requires an interchangeable (Adaptall) mount to enable it to fit the camera. The second lens (model AF272E) is the second to latest version, is autofocus and has a camera specific mount.
Although these lenses were primarily sold as macro lenses they also make great portrait lenses due to their ideal focal length.
Technical specifications for the lenses are as follows:
52B: Maximum aperture f2,5, minimum f32, construction 8 elements in 6 groups, filter size 49mm, weight 420g (excluding mount), maximum image 1:2 life size. 1:1 available with addition of dedicated extension tube or tele adapter.
AF272E: Maximum aperture f2,8, minimum f32, construction 10 elements in 9 groups, filter size 55mm, weight 405g, maximum image size 1:1 life size.
The two lenses are quite different in construction and appearance, the 52b being made of metal, shorter with a ribbed focusing ring and prominent front and rear elements, the shape and position of the rear element can cause issues on digital cameras, due to reflections from the element onto the sensor, causing a blue circular spot in the centre of the image. No such problem with the AF272E, the optical arrangement means lens elements are placed much deeper inside the (longer) lens barrel, the lens is made mainly of polycarbonate with a small amount of metal.
For the sharpness tests we used a Nikon D300,set to jpeg fine.
Model 52B @f2,5
Model AF272E @ f2,8
Model 52B @ f8
AF272E @ f8
Model 52B @ f16
Model AF272E @ f16
Blue spot at centre of lens with Model 52B
Conclusion
Surprisingly there is not a huge amount of difference in sharpness between the two lenses, the manual focus lens is a fraction behind wide open, but after that both lenses are evenly matched, one strange occurrence is that the autofocus lens although an f2.8 reports to be operating at f3,1 when set at f2,8
If you come across one of the early manual lenses, are happy to, focus yourself, can live with lens being only half life size unless you use the dedicated extension tube or converter, thus losing at least a stop of light, finally are careful not to shoot towards the light (or are happy to digitally remove the blue centre spot), why not give it a go.