One of the legendary wideangles for SLR users, the Carl Zeiss ZF.2 2.8/21 Distagon T* (referred to simply as the ’21′ after this) is a fairly complex – by Zeiss standards, anyway – telecentric design with 16 elements in 13 groups and a floating rear group for close range correction. As with most of the modern Zeiss lenses, it’s based on a derivative of the older Contax/ Yashica 2.8/21 Distagon (however, that was a 15/13 design). It’s currently available in Canon (ZE, fully electronic) and Nikon (ZF and ZF.2, the latter of which is fully electronic) mounts.
Like all Zeiss lenses, this is a piece of glass that is extremely solid, moderately heavy (~620g) and very well built all-round – it’s like an old-fashioned scientific instrument, in a good way. There is no plastic on this lens; except perhaps some of the baffling at the front and rear. The barrel is black-anodized aluminium, with chrome front bayonet for the hood, and chromed brass rear mount. My two minor complaints about build quality relate to the hood lining and mount – like all Zeiss lenses, the mount seems to wear very quickly, showing brassing after just a dozen or so lens changes. The hood is metal, solid, and locks into place on the front bayonet thread with a reassuring click – and doesn’t move thereafter. However, it also has very crisp edges that are prone to denting, and the felt lining can easily start peeling around the front edge if you get it caught on something. A thin rubber bumper lip around the front edge would solve both problems handily (and if I’m not mistaken, the hoods for some of the Sony Alpha Zeiss lenses have this).
One curious design quirk is the front portion – it reminds me very much of a martini glass. Although the glass itself appears to be able to fit within a similarly-sized housing as the 2/28 Distagon, the front filter thread is a whopping 82mm. I presume this is so one can stack filters without worry for vignetting, but it could also be because some parts such as the hood and bayonet are shared with the similarly martini-like 4/18 Distagon. Unfortuantely, this makes the lens rather cumbersome to pack as it occupies virtually cube-like dimensions.
This is, of course, a manual focus lens – apparently the tale goes that all of the autofocus patents are held by the Japanese, except for Hasselblad, who bought technology from Minolta. Needless to say, these patents are being kept very closely guarded; I honestly can’t think of a reason to buy a large portion of Nikon and Canon’s lenses if I could get autofocus with Zeiss. Industry politics aside, the manual focus ring is perfect – spinning freely enough to change focus distance quickly, but not so loose that you can’t set the distance precisely. The amount of damping is perfect. Why Zeiss can’t make all of its other lenses feel like this is beyond me – they’re mostly a bit too heavy in feel for my tastes, especially in a fast moving reportage scenario.
The near focus limit is just 22cm, which makes for some very dramatic closeups indeed; however don’t be expecting fantastic magnification because it is, after all, a 21mm lens – which means you’re looking at 1:5 or so. More importantly, however, is that optical performance across the frame is maintained even at this focusing distance; undoubtedly thanks to the floating rear group that compensates for near aberrations. I personally can’t think why I’d use it at this range, though it might make an interesting lens for food photography on the OM-D – being a 42mm equivalent.
Sharpness and resolving power are excellent; this is one of the few wides that really does the D800E sensor justice – even into the edges. The center is already extremely sharp from wide open, and the extreme corners catch up at around f5.6 or so. There are very mild traces of lateral CA wide open in the corners with high contrast subjects and the D800E; they’re not visible at all on the D700 and DX bodies. And there’s no odd color smearing, either – everything resolves in the same spatial location, which can’t always be said of wide angles (the Sigma and Voigtlander 20mms come to mind). Interestingly, this lens has an extremely impressive MTF chart* – almost flat by f5.6 – made even more impressive by the fact that Zeiss MTF charts are measured averages not theoretical maximums.
*The interpretation of which will be the subject of a future article.
What of the other optical properties? Well, there’s some vignetting; around 1-1.5 stops in the corners at f2.8, but it’s almost entirely gone by f4. There’s distortion, too; up to 2% taking an odd moustache or sombrero-shaped pattern that isn’t so easy to correct manually, but can be taken care of easily by ACR’s built in profile for the lens. Bokeh is neutral and pleasant, with no hard edges; that is, when you can get enough subject separation to see any bokeh in the first place. You’re pretty much going to be at hyperfocal from 2m if you set f5.6.
Finally, a quick word on that famous Zeiss microcontrast – it’s present as expected. Microcontrast is the visible result of several optical properties: high resolution; even and high spectral transmission, and as little chromatic aberration as possible. The 21 has all of these things. Resolution and chromatic aberration are functions of the optical design; transmission dependant on the glass types and coatings used. As with all Zeiss lenses, the transmission of this lens is very high thanks to the excellent coatings – note how in the images above, the front few elements mostly disappear; this is due to the surface coatings not allowing reflected light. It’s especially important for maintaining contrast; good coatings manifest themselves in a deep, saturated look that I like to think of as ‘tonal richness’. But I digress: the T stop of the 21 is 2.9, which is just 0.1 stop down from the physical aperture of 2.8. It means that you’re pretty much going to get as much light as you can out of the optical design.
All of these technical qualities are useless if the lens doesn’t produce great images; it does. The 21 somehow manages to be an excellent balance of technical competence and personality; it’s not entirely a transparent lens, but its personality definitely lends a positive influence to any images shot with it. And despite the distortion, you can use it for architectural work uncorrected if you don’t put any straight edges too close to the frame border – in practice, it’s not that noticeable; far more obvious will be whether your camera is level or not. For critical applications, correct the distortion with ACR/ Photoshop. The drawing style of the 21 falls somewhere between the 2/28 Distagon and the 2/50 Makro-Planar; both resolve at very high levels, have excellent microcontrast and transmission, but the difference in ‘personality’ here seems to be related to the amount of field curvature and distortion; the 21 is not perfectly flat field, but it’s pretty close – which is a surprise for an ultrawide.
One of the things I like very much about the way this lens renders – and perhaps more generally about the 21mm field of view – is that it’s about as wide as one can go without the perspective starting to render subjects unnaturally, so long as you carefully place the foreground in your images. It’s wide enough to convey space – especially in tight interior quarters – but not so wide as to appear unnatural, which is a problem I’ve always found with ultrawides. It’s simply impossible to achieve anything approaching a natural-looking perspective with anything wider because of the configuration of our own eyes: 21mm is roughly equivalent to your peripheral vision. Psychologically, our brains just aren’t conditioned to interpreting anything wider on a regular basis.
I want to add a quick note on compatibility: thanks to it being a telecentric design, the lens actually works very well on smaller formats – Micro Four Thirds, for instance. Carrying say a Nikon FX body, a M4/3 body and the 21 and 100mm lenses gives you an optically excellent and reasonably light landscape kit covering 21, 42, 100 and 200mm – a nice spacing of perspectives. I did this for several early-morning walks in Switzerland whilst on my last assignment, except I had the 1.4/85 Planar instead of the 2/100 Makro-Planar.
Up until fairly recently, I’d done my wide architectural work with either a Voigtlander 20/3.5, whose low contrast and lack of bite I didn’t like very much; or the Nikon AFS 24/1.4G, which didn’t have the same microcontrast as the Zeiss. All I can say is that I have no idea why I didn’t get the 21 sooner; it’s another one of those truly outstanding lenses that is a must if you’re a wideangle shooter. It isn’t the most discreet lens for documentary work, but the pictorial results are excellent; but it is an absolute no-brainer if you’re an architectural or landscape photographer. Highly recommended! MT
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