AF Tamron SP 90/2.8 Macro 1:1

 

Lens construction: 10 elements in 9 groups
Focus distance: 0.29 m to infinity
Angle of View: 27°
Max. reproduction ratio: 1:1
Aperture scale: f/2.8 to f/32
Attachment size: 55 mm
Diaphgram blades: 9
Lens hood: C9FH (supplied)
Dimensions: 71 mm (dia.) x 97 mm (length)
Weight: 403 g

 

 

 

 

Introduction

The portraiture capabilities of the popular Tamron MF 90 mm f/2.5 are further enhanced in this AF 90 mm model. For handling ease, the lens weighs a mere 403 g (AF Nikon mount), making it ideal for taking advantage of its maximum macro magnification ratio of 1:1. Its fast f/2.8 aperture and 9-bladed diaphragm help in producing soft out-of-focus backgrounds.

Technical information

The AF Tamron 90 mm f/2.8 has a floating elements design. The effective focal length at the minumum focusing distance (29 cm) is 72 mm. In fact, at 1:1 the effective focal length of a macro lens is given by the focusing distance divided by four. The shortening of the focal length in new macro lenses, determines also rather short working distances. The plot below shows the variation of the focusing distance (magenta curve) and of the working distance (green curve) measured as a function of the reproduction ratio (magnification).

The data show that the working distance (WD) is just 10 cm at 1:1. This value is rather low compared to those attainable with other 100-105 macro lenses, as shown in the Table below:

 

lens

 WD (cm) at 1:1
Minolta AF 100/2.8 Macro 16.2
Contax Makro Planar J 100/2.8 15.5
Canon EF 100/2.8 Macro USM 15
Nikon AF 105/2.8 D 13.6
Sigma AF 105/2.8 Macro EX 12
Pentax FA 100/2.8 Macro 11.1
Tamron AF SP 90/2.8 Macro 10

 

In order to increase the WD, we can use a high quality 1.4 X teleconverter. The data reported in the table below show that the WD at 1:1 is 13 cm when a 1.4 X extender is employed. Moreover, the use of a 1.4 X telextender allows to increase the maximum magnification by the same factor (1.4 X) at the minimum focusing distance.

 

Reproduction ratio

(with 1.4X)

Focusing distance

(cm)

Working distance

(cm)

1:4

71

54

1:3

57.5

40.5

1:2.8

55

37.5

1:2

44

26

1:1.5

39

20

1:1.3

36.5

18

1:1

32.5

13

 

Field behaviour

The lens is quite sharp at all focusing distances. It's therefore suitable for both landscape and macro photography.

 

Nikon F 801 - AF Tamron 90/2.8 Macro - Gitzo 1320 tripod - Velvia

Camosciara (Abruzzi National Park)

 

Nikon F 801 - AF Tamron 90/2.8 Macro - Velvia

Butterfly (Coenonympha pamphilus)

 

Nikon F 801 - AF Tamron 90/2.8 Macro - EliteChrome 100

Rose moss (Portulaca grandiflora)

 

Nikon F 801 - AF Tamron 90/2.8 Macro - E 100 VS

Ear of spelt

 

This lens suffers heavy flare in some critical counterlight situations, as shown in image a below:

 

a )

 b )

 

To avoid flare, I used my left hand to shield the sunlight (image b). 

The AF Tamron 90/2.8 exhibits a slight vignetting at full aperture (image A below). Image B has been taken at f/4. Vignetting is no more detectable.

 

A : f/2.8

 B : f/4

 

Since the filter thread does not rotate when focusing, polarizing filters are easily accomodated.

 

Text & images © Copyright Riccardo Polini