HD Pentax-D FA* 70-200mm F2.8 ED DC AW

Vs. Tamron's 70-200mm

The first version of the Tamron 70-200mm F2.8 Di LD Macro was announced in 2008. It was updated in 2012 but the newer version is not (yet) available for Pentax. With a street price of $769 as of September 2016, it is less than half the price of the new Pentax 70-200mm. It appears like an even better deal when compared with lenses from other manufacturers (the Sony's $2600 comes to mind). The design is 8 years old, and lacks some of the bells and whisles of newer lenses. How does it hold on?

This section will present briefly the Tamron lens, insisting on what makes it different from the Pentax version.  Image quality comparions will follow on the next few pages.

Body

Even at a casual glance, the Tamron lens is obviously different from the Pentax. The length difference (about 1cm) is not easily visible, but the diameter shows where the designers made different choices.

The taper on the Tamron's body makes it easier to manipulate than the Pentax 70-200mm, whose constant diameter means that photographers with small hands might have trouble wrapping their fingers around it.

The weight is substantial but, for such a large lens, fairly light indeed. It is only 100g heavier than the Pentax 60-250mm, for instance. This Tamron lens is much better suited than the Pentax for handheld photography. In fact, one could argue that this is one of its main design perks. The Tamron lens feels light enough that it shouldn't put any strain on the mount when handled by holding only the camera without supporting the lens.

The focus ring is located near the front of the lens, while the zoom ring is near the body. The latter's movement is limited by the presence of the tripod foot, which is much to close to the body to let fingers pass underneath. This makes for a more compact design, at least. The feeling of the zoom ring is completely lifeless; this is one area where the lower price shows. The zoom ring moves with too much looseness, poor friction, and the feeling that plastic is slipping on plastic. This is disappointing. The zoom comes to hard stops at both ends.

Removing the collar takes longer than what is desirable. The surface of the lens underneath the collar is metal like the rest of the body, and small shoulders are used to make sure the collar keeps its position on the shaft of the lens. The collar is also metal, with a smooth surface, probably teflon, on the inside. The release screw also serves as a control for friction, but it is hard to adjust precisely. There are no notches to orient the lens at straight angles when rotating it, only a dot to align the line drawn on the collar at the horizontal position. Notches would give more confidence that the alignment is optimal.

The lens has several nice touches, like the gold ring yielding a level of elegance. The lettering is kept to a minimum, and even the "Tamron" name is small and unobtrusive.

Build Quality

The Tamron is a very well-made lens. Its body is mostly metal, with rubber rings for focus and zoom. When compared with consumer-grade lenses, it is obvious that it belongs in a higher category.

It is when compared with the best that it pales. Side-by-side with the Pentax 70-200mm or 60-250mm, there is an obvious difference between the three. The choice of material for the rubber (harder on the Tamron, softer on the Pentax), the texture of the metal parts, the movement of the rings, even the hardness of the focus distance window all contribute to this impression. In particular, the AF/MF clutch does not inspire confidence (more on that later).

Again, this is all a matter of perception. The lens has been available for many years and has an excellent track record. The comparison leaves the user with the feeling that the Tamron lens should cost less than others. It is a good thing that it does.

Features

Special features are kept to a minimum. There are no switches or dials, and the only uncommon control is the focus clutch.

Autofocus

Autofocus is carried out via screwdrive, but is very fast and reliable, especially when using the viewfinder (Phase Detection AF). AF data will be found in the next section. 

The AF noise is best illustrated by the view below, which shows the lens trying to lock focus in very low light, on a subject about two meters from the font of the camera.

Note that small adjustments are comparable with other scerw-drive lenses: discreet if not noiseless. Only when the lens needs to go through the whole focus range is the noise truly noticeable.

Manual focus is achieved by pulling the focus ring towards the camera body. When in autofocus mode, the letters AF show in white, with the letters MF in blue below them. When the ring is pulled, only the MF letters show.  There is no Quick Shift full-time manual override; this lens operates as Pentax FA*-series lenses did with an AF/MF clutch.

Going from MF to AF is easy but noisy, the lens making an audible sound when moving the clutch. However, going from AF to MF is not as simple. The ring must engage in the MF gears, but if they are not properly aligned, the gears won't lock together completely. Because of this, it is often necessary to move the ring back and forth a bit in order to properly lock it. This means that keeping the same focus point while engaging the AF clutch is unlikely.

The video below illustrates the noises the lens makes when switching back and forth between AF and MF.

When the ring is in the AF position, it is impossible to focus manually, even if the camera body is set to MF. We were not fans of the clutch design when we reviewed the Tamron 90mm macro, and that opinion remains. In order to switch to manual focusing, the ring must be pulled and the camera must be set to MF. Otherwise, gears can be heard turning and there are risks of damaging the camera's screw-drive.

When the camera body is set to AF and the lens to MF, the system will autofocus, and the focus ring will rotate (which can put stress on the AF system, considering the weight of the ring). With both components set to AF, the distance scale moves during AF, but the ring remains immobile.

Verdict

At the asking price, the Tamron looks like a bargain. And, for better or worse, it is one. There are few design flaws (the position of the foot and the focus clutch benig the main ones) but no perks either. The body is solid and well made, but it lacks some of the features one has come to expect from professional equipment. The AF/MF clutch is complicated and leads to inaccuracies.