Tamron 90mm Macro vs Pentax 100mm WR: Review

Tamron 90mm Build Quality

The Tamron macro lens is a large piece of optics, 97mm long and 72mm large at its widest. It uses 55mm filters, a somewhat uncommon diameter. The lens is full frame, covering the 35mm image circle. It has a whopping nine straight aperture blades.

The body is made entirely of plastic, but feels solid nonetheless. Incidentally, the finish fits very well with that of the K20D, and probably of other Pentax bodies. The lens mount is metal. Interestingly, there is an aperture ring, so the lens can be used with older film bodies and macro accessories. However, the operation of the aperture ring is not particularly smooth, as is the case for most modern lenses. The lens extends by a fair margin when focusing at close distances. A slight wobble of the inner barrel was observed when the lens was extended at its maximum length.

The front optical element is recessed by more than 4 cm from the front of the lens itself. From an optical design point of view, there is no obvious reason for this design choice. The lens could have been made shorter by designing its outer barrel differently and bringing the front lens element closer to the front of the lens barrel. We must assume that Tamron’s engineers had good reasons to make such a choice, but it is far from obvious what these reasons are.

Because of the recessed front element, the use of the provided hood does not seem mandatory. Mounting the hood is easy, and it reverses for storage. Mounting the hood reversed was harder than we would have liked, on our sample at least, with a lot of friction.