I bought this lens about 18 months ago as a 1:1 macro lens to be a supplement to my Tamron 70 – 300mm Macro Zoom. Although the zoom is a nice lens and was remarkably cheap (about £90) I wanted a lens that would produce a full 1:1 macro and be of better quality. Because I owned a Pentax camera, the choice in a Pentax K mount came down to
- Pentax SMC-D FA 100mm f/2.8
- Sigma 105mm F/2.8 EX DG
- Tamron 90mm F/2.8 SP Di
Of these the pentax removed itself quite early because of price. It was close to twice the cost of the other two and I just couldn’t justify it. I spent many hours pouring over images in flickr groups for the two lenses and came to the conclusion that there wasn’t much to choose between them, but the Tamron was a bit cheaper so I got that.
The lens is quite compact, being about 4 inches in length but extends to about twice that length when the focus is set to it’s closest extreme. Because I bought a Pentax fit lens (to work with my then current camera a Pentax K-r) there is no internal focus motor. Focusing is driven by a motor in the camera body via a screw thread which makes it a bit noisy and can be slow. This isn’t really a problem when the lens is used as a short telephoto, but can seem imprecise when used as a macro lens. However in these circumstances I tend to use it on manual focus anyway. In manual focus mode the focus ring is nice and deep and easy to grip and the focus operation is smooth and precise. It’s actually a doddle to use and focus quite quickly in macro mode as you get used to moving yourself and the camera to a close position and then finishing off with the focus ring.
For those situations where you use auto focus, there is a switch on the side of the lens marked FULL and LIMIT which sets the distance the focus ring will travel, limiting the hunting about that invariably happens as the correct focus point is found when switched to LIMIT.
There is a wide aperture range of F/2.8 to F/32 in one stop steps. This makes the lens both quite fast as a short telephoto and gives it a reasonable depth of field when used as a macro lens, although of course at f/32 there won’t be much light getting to the sensor ! When the lens is set to the A setting, the aperture is controlled by the camera (obviously) but the inclusion of the individual F stops means it can also be used on older cameras without electronic control. I have not used it to take pictures on a full frame 35mm camera but viewing through the viewfinder of my Pentax SFXn with it attached, suggests it would work OK as there is no vignetting.
At 90mm focal length you need to get quite close to your subject in macro mode to get to a 1:1 image. I notice this particularly because I had taken lots of macro images with the 70 – 300mm zoom which has its macro focusing at the 300 mm end and you are a few feet away from the subject. With the 90mm the subject will only be a few inches away. I haven’t found this to be a problem but you need to be aware of it.
Of course the main point of interest when it comes to a macro lens is the quality of the images it produces. I have found it to be an outstanding lens for the price and certainly matches the capabilities of the Pentax K-r which I used when I bought it. I’ve subsequently upgraded to a Pentax K-5 and I still find it to be an excellent lens, capable of very fine detail, contrast and colour.
This is a small gallery of favorite images I’ve taken with the Tamron 90mm macro lens – for best results and to view the images in full size, click on any picture.