Zeiss Sonnar T* 90mm f2.8 — A Long-Term Review
The best camera is the one you have with you. That same mantra applies to lenses as well: a lens too heavy or cumbersome to bring with you is a lens that remains unused. For those who seek a compact and lightweight photography kit, small, modern telephoto primes in the 85–100mm range seem to be a rarity these days. Lenses like the Fujifilm 90mm f2 and Sony FE 85mm f1.8 are quite excellent, and I cannot call them overly-large in light of their optical performance. Yet I am left wanting for a lens that much smaller, with just as much reach.
My search for a manual focus telephoto prime that is small and yet fairly affordable led me to the Zeiss Sonnar T* 2.8/90 for the Contax G mount (I’ll call this the Zeiss 90mm going forward, for brevity’s sake). In spite of its price ($130–150 on eBay) and small size, its optical qualities are much exalted by those who have used it. This may not come as much of a surprise considering the esteemed “Carl Zeiss” name engraved upon the front of the lens, although the lens was actually made by Kyocera (whom the Contax brand had been licensed to at the point).
I’ve owned and used this lens regularly for the past 2 years on my Fuji mirrorless cameras (X-T10, then X-E3, and now a X-T2), and it fulfills most of my needs for a telephoto lens. In fact, I’ve owned the native Fuji 50–230mm and 55–200mm, and sold them off in favour of keeping this lens. This review will summarise my experiences with this lens over the two years I’ve used it: spoiler alert, it’s a good lens. But you didn’t come here just to read that, so I’ll explore the pros and cons I’ve noticed over my time with this lens.
Build and Size
A rather diminutive lens, it is not much bigger than the line of F2 primes from Fuji. I like to think of it as a long-lost sibling of the Fujicrons. It is rather light as well, weighing in at 240 grams.
Aperture is controlled with an aperture ring that is only 6mm thick. This may make it a bit hard to grab ahold of, but the knurled surface means that it hasn’t been a problem in my use. It clicks in full stops, from F2.8 to F22.
You might think that the ring below the aperture ring controls focus, but it is in fact used to mount the lens. Rather than turning the whole lens to lock the lens into the mount like on most other bayonet systems, this locking ring turns the bayonet teeth within the lens to secure itself to the camera/adapter.
Where’s the focus ring then? Well, there isn’t one. The Zeiss lenses for the Contax G mount are screw-drive, with no way to adjust focus on the lens itself.
Manual focus is achieved through a dedicated distance dial on the Contax G1, and a focus mode selector on the G2 (in combination with the front dial). When adapted to a mirrorless camera though, the adapter must provide a means of turning the screw drive in the lens to achieve focus. As you can imagine, that can get rather complicated. Thus, I’ve dedicated an entire section to adapting this lens.
Adapting to mirrorless cameras
The Contax G mount has a flange distance of 29mm. As this is shorter than the flange distance of common SLR mounts like the EF and F mount, lenses for the Contax G mount cannot be adapted to Canon and Nikon DSLRs. However, they can be adapted to most modern mirrorless camera mounts with a relatively thin adapter.
There are several adapters available for Contax G lenses, and they can be categorised into three types:
1. Thin-ring type: generally the cheapest and smallest. I have a no-brand one that is not smooth and often gets stuck thanks to poor tolerances. Trying to focus is a miserable experience. Even those under brand names seem to have the same design (the Kipon one might fare better). I would not recommend one of these unless you can get your hands on one in a store and ensure that it operates smoothly.
2. Thick-ring type: these use a much thicker ring that encircles the base of the lens. The increased size of the ring helps a lot with handling but contributes size and weight. These tend to be smoother and more well made. As far as I know, only the Fotodiox Pro, Metabones and Ulata fall into this category. I use the Ulata myself.
3. Autofocus: Techart Contax G adapter. Only available for E-mount, unlike the others. A motor drives the screw in the lens to enable autofocus, but manual focus is also possible with a small dial on the side.
For most, the second, thick-ring type is the most desirable kind of adapter. However, there is one more option, that is quite a bit more involved: a lens rehousing. Some folks have managed to rehouse the lens inside the body of another vintage lens, and make use of that lens’s helicoid to achieve manual focus in a fashion similiar to most other manual lenses. You can find more at this thread on Fred Miranda.
Image Quality
Sharpness isn’t the only metric by which a lens should be measured, but for many, it can be the most important.
The following crops were shot with the lens mounted on a Fujifilm X-T2, so there is a 1.5x crop factor at play here. The camera was mounted upon a tripod, and the shots taken with electronic shutter (to prevent shutter shock). Raws were processed in Capture One and the graphic was put together in Photoshop. To view these crops at 100%, you can download full sized versions of the below graphics here, and open them in your preferred image viewing software.
To eliminate the effects of field curvature, the centre crops were focused for the centre, while the corner crops were focused at the bottom left corner, where the crop was taken from. While comparing the two sets though, I couldn’t see much evidence of field curvature.
In general, the sharpness of this lens is beyond reproach for my uses.
The centre is already very good at f2.8 but both sharpness and contrast improve upon stopping down. The images are rather excellent from f4 all the way to f8. If I zoom in to 200% or 400%, peak sharpness seems to be acheived at f5.6 but the results are otherwise indistinguishable in this aperture range. Stopping down to f11, you can see a small loss in sharpness due to diffraction. f16 is slightly worse but still usable in my eyes, but the sharpness really takes a hit at f22.
The corner actually follows very closely behind the centre at f2.8. I would say it’s still very good but slightly worse than the centre performance. From there the story is very similiar to centre performance: excellent from f4 to f8 with a peak at f5.6, with declining sharpness further stopped down due to diffraction. Again, f11 and f16 are still very good but I wouldn’t advise shooting at f22.
For more in-depth testing (like bokeh, flare resistance and close-up performance) and results on full frame digital cameras, you can refer to this excellent review at phillipreeve.net by Phillip Reeve. (It was in fact this review that drove me to purchase this lens.)
Use Cases
The Zeiss 90mm gives me a 135mm equivalent field of view on my Fujifilm APS-C bodies. As with most telephoto primes, it works well for portraiture. The closest I usually come to shooting portraits is photographing stray cats, but I do have one picture of a human here for what it’s worth. The f2.8 aperture isn’t the fastest around if you love obliterating your backgrounds, as some portrait photographers do.
Despite this focal length’s association with portraiture, I most enjoy using this lens for architecture. A longer focal length allows one to isolate details and create more minimal compositions, while also providing a healthy dose of compression and reach for cityscapes. And this lens does rather well for that too, with its excellent sharpness through the frame, and the slower f2.8 aperture being a non-factor (when one needs to stop down for greater depth of field anyway).
Verdict
The lens is rather affordable today: it can be found on eBay for under USD$150 if you’re patient, although the black variety costs more due to its limited availability. While it is a bit more costly than similiar vintage lenses for SLR mounts such as the Nikon 105mm f2.5 and Olympus OM 100mm f2.8, it has the advantage of being smaller and lighter after taking the adapter into consideration.
The biggest downside is perhaps the need for a unique adapter that drives the screw in the lens. Even the best of these adapters still results in a less-than-ideal manual focus experience, especially when compared to other lenses with true focus helicoids. If you can live with this compromised manual focus, I would wholeheartedly recommend this as a sharp and compact telephoto prime. It is easily my favourite vintage lens for adapted use with my Fujifilm cameras.
Unfortunately I have not had the chance to use this lens on a Contax G1 or G2 body (as it was intended to be used). I’m looking forward to doing so one day when I can land a good deal on either of those bodies.
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