If you looked for the signs it was obvious way back when the 100 was first released. Sony was on a mission. The company was laying down the foundations for not just this first model, but for a whole system of cameras ranging from economical entry designs through prosumer options to top of the line flagship offering that we now know as the 900. Nowhere was this more obvious than with their lens offerings. As well as a few rebadged models from the Minolta stable, the company released some serious new glass, that was more suited to high end usage than the being strapped to the front of a modest 100. Yes, we are talking about the range of pro-optics engineered by Zeiss and produced by Sony.

The signs were clear. It was obvious that Sony wanted to provide the discerning photographer with some of the sharpest lenses available, but beyond that, they knew that they had the 700 and 900 coming down the shute, and that these models would be able to take advantage of the extra resolving power and contrast that the Zeiss offerings provided. First shipped were the 135mm f1.8 (SAL135F18Z) and 85mm f1.4 (SAL85F14Z), which both offer full frame coverage, and the 16-80 mm f 3.5-4.5 (SAL1680Z) for APS-C models. Next off the production line was the all purpose 24-70mm F2.8 (SAL2470Z) which to my mind is the perfect companion for the 900.

135mm and 85mm

The first thing that strikes you about both fixed lenses is the sheer size of the front element. With both units sporting large maximum apertures, f1.8 and f1.4, this is no real surprise. Such specifications make these units great for low light shooting and terrific at separating subjects from their backgrounds via deft use of depth of field effects. Both are sturdily constructed and sit well in the hand. Auto Focusing is accurate, but can at times, feel a little old fashioned as neither unit has a built in motor, and there is a lot of glass to shift around when searching for AF points. That said, body driven focus is more than up to the sort of tasks that the 135mm and 85 excel at, that is, portraiture, editorial and studio based capture.

The Zeiss Zooms – 24-70mm and 16-80mm

Now despite the convenience factor and the sheer weight of numbers, most ‘old skool’ photographers still believe that a fixed focal length or prime lens will drastically outperform a zoom lens at the same focal length. It is true that in the early days there were some really soft zoom lenses on the market, but fortunately this level of prejudice is no longer valid. Take for instance the Zeiss 24-70 2.8. This is an outstanding lens exhibiting great sharpness across both zoom and aperture range with a wide maximum aperture to boot. In my opinion, such a lens should be made standard on the 900 providing as it brings great optical performance to a sensor that captures an incredible amount of detail (24.6 Mp in total). The marriage is one made in photographer’s heaven.

The 16-80mm brings to APS-C cameras in the range the same general purpose coverage that the 24-70mm does for the 900. Though the specs for this lens are not as high as the 24-70mm, it has a smaller widest aperture which varies across the zoom range and is not quite as sharp at the edges, the unit is well suited for travel photography, portraiture and landscape work. In fact in the time that I have owned it, the lens rarely leaves the front of my 700.

Objectively testing sharpness

When I first started playing with these lenses I couldn’t believe the sharpness that I was seeing. Not since I was back shooting 5 x 4 inch cameras had I been able to visibly discern such sharpness when comparing lenses. Now, that said, I did wonder if I was being wowed by the Zeiss name, so I double checked with the results of tests carried by Klaus Schroiff over at www.photozone.de. He regularly tests camera and lens combinations and provides a set of Modulation Transfer Function (MTF) graphs. Don’t panic I’m not going to bore you with an explanation of how theses graphs are created (if you are interested, check out the links on the site), instead it is suffice to say that the higher the values of ‘line widths per picture height’ (LW/PH) the greater the appearance of sharpness.

Now, this is an objective test, so there is no room for the Zeiss ‘wow’ factor here. The results speak for themselves. The 135mm ranges from 2136 LW/PH at f/1.8 at the edge of the lens to 2324 at the centre at F/4.0. (click here to view the 135mm graph). To put that in perspective, a good quality standard lens would average around 1750 LW/PH. What about the other lenses? Well they fair just as well. The 85mm ranges from 2006 to 2265 LW/PH (click here to view the 85mm graph). That’s well and good for fixed focal length lenses which traditionally have better sharpness results, but what of the Zeiss zoom lenses on offer? Well you may be surprised to know that the 24- 70mm f/2.8 when set to 24mm ranges from 2034 – 2367 LW/PH which is a great performance for any lens, zoom or not (click here to view the 24-70mm graph). The results for other focal length settings are just as impressive. The APS-C matched 16-80 doesn’t fair quite as well. Centre sharpness is very good averaging 2100 LW/PH, but the sharpness at the extremes sit around 1700 LW/PH for wide angle settings (click here to view the 16-80mm graph). Now this is by no means unusual for such lenses, nor does it mean that poor image quality will result, it is just that these figures aren’t as stellar as the other Zeiss lenses that we have looked at.

Pro - from start to finish

So it is clear that the Zeiss lenses are substantially sharper than the average and on par with some of the best lenses available for 35mm cameras. Don’t believe me? Check out the results for the other lenses on Klaus’ site. It is also clear that Sony has a firm commitment to providing a range of different levels of cameras and lenses to suit a variety of photographers and shooting needs. For my part, I am happy that part of their plan was to commission Zeiss to supply high end glass for their system. It gives pros, and serious amateurs alike, access to some of the best optics around.

Lens model	Focal Length on a full frame sensor camera (900)	Equivalent focal on smaller APS-C equipped cameras (700, 350, 300, 200, 100)
Carl Zeiss Planar T* 85mm F1.4 ZA (SAL85F14Z)	85mm	127.5mm
Carl Zeiss Sonnar T* 135mm F1.8 ZA (SAL135F18Z)	135mm	202.5mm
Carl Zeiss Vario-Sonnar T* DT 16-80mm F3.5-4.5 ZA (SAL1680Z)	_	24-120mm
Carl Zeiss Vario-Sonnar T* 24-70mm F2.8 (SAL2470Z)	24-70mm	36-105mm

Note: My thanks goes to Klaus Schroiff from www.photozone.de who kindly provided the MTF graphs for this article. For the full and comprehensive reviews of the lenses mentioned here go to his site and click on the Sonyheading in the Review Section.