The standard 18-70mm kit lens on the Sony Alpha does a reasonable job, but it’s not the best lens in the world and suffers particularly from chromatic aberration near the edges of the frame.

Kit zooms are renowned for value rather than optical quality, so if you want to know what your Alpha can really do, you might be taking a close look at the Carl-Zeiss-badged 16-80mm lens. It’s designed specifically for Sony Alpha SLRs and, unlike some other recently announced Zeiss lenses, it’s for APS-C sensors only – it’s not a full-frame lens.

They say with lenses that you get what you pay for, and with this price tag, you’d be entitled to expect plenty.

Its technical advantages are subtle rather than striking. If you round up to the nearest millimetre, its zoom range is equivalent to 26-128mm on a 35mm film camera, while the kit zoom is equivalent to 29-112mm. That’s a modest advantage at the wide-angle end of the zoom range, but still a useful one. The main advantage is at the long end, though. Not only does the Carl Zeiss lens offer a longer focal length, it does so at a slightly wider maximum aperture, topping out at f4.5. In fact, it has a half-stop advantage in speed through much of the zoom range.

Other advantages are subtler and relate to look, feel and handling. The 16-80mm has a neat profile with no fancy adornments and a small blue ‘Zeiss’ logo on the left side. The zoom action is smooth and fast, though not perfect. The manual-focusing ring has a short travel, but does feel a little rough. It’s noticeable, though, that there’s little or no ‘slop’ in the front element during focusing. The focused distance is visible through a clear window in the top of the lens.

The autofocus is fast and accurate, though not particularly quiet. Even the kit zooms on Nikons and Canons are noticeably quieter than this and it really is an annoyance when you're paying this much.

The overall build quality is good, though the plain design (a good thing in itself) does draw attention to the plastic finish. It’s a step forward in quality from the kit zoom, but the 16-80mm is going to have to outperform it optically if it’s to justify its price.

We were able to test an 18-70mm directly alongside the Carl Zeiss, and the Imatest results do show some very interesting differences. Surprisingly, the 18-70mm outperformed the Carl Zeiss at wider apertures, but began to tail off at medium apertures. The 16-80mm, by comparison, showed lower sharpness at wider apertures, but made up the difference by f8-f11.

There’s a great danger in relying solely on resolution figures, though, and even these need to be interpreted carefully. For example, although the 18-70mm kit lens performed well at shorter focal lengths, its performance dropped considerably at the long end – a characteristic of inexpensive zooms with long ranges. Across the full range of focal lengths, the Carl Zeiss lens has the advantage.

It also has more consistent sharpness across the frame, and at the shorter focal lengths there’s almost no chromatic aberration at all. As we said earlier, the 18-70mm suffers badly from chromatic aberration. Indeed, this completely outweighs any resolution advantages. Even this isn’t completely clear-cut, though! The Carl Zeiss lens is clearly sharper at maximum focal length, but while the 18-70mm kit lens shows little colour fringing at this point, it’s starting to appear in the 16-80mm lens’s shots, which just isn't good enough.

You can’t just compare lenses in the lab, of course. You have to go out and shoot pictures with them, and that’s exactly what we did. Here, the Zeiss lens proved easy and comfortable to use. The pictures show very good contrast and colour, and the slight increase in zoom range over the standard kit lens is genuinely useful in some situations.

It’s also obvious, though, that this lens won’t transform the quality of images shot by the Sony Alpha. Its advantages over the standard zoom are too subtle for that, at least with this camera.

The fact is that it’s a lot of money to spend for a comparatively small gain in image quality and range. Maybe with a better camera or different processing the results might be more obvious? It could be that the Carl Zeiss 16-80mm will come into its own with the Alpha’s successor.

Final Verdict It’s a nice lens, but on the Alpha 100 the 16-80mm doesn’t bring enough of an improvement in image quality to justify the price OVERALL

Our lens reviewer, and technical expert, Rod is a veritable photographic encyclopaedia. His illustrious CV has seen him write for many mags, websites and journals.