In the left corner: the Rokinon (a.k.a ‘Samyang’, in some parts of the world) T-S 3.5/24 ED AS UMC, from Korea. In the right corner: the Nikon PC-E 24/3.5 ED. One weighs in at a hair under $2,000, the other, closer to $850. I have to be honest, the Samyang has only come onto my radar because of the enormous difference in price – I admit curiosity as to what we’re really giving up for the delta. The only real uses for these lenses – other than bragging rights – are to shoot architecture; Putrajaya’s Putra Mosque plays host to us for this testing session.
Technical notes: During this test, I shot both lenses from the same tripod position with the same settings on the barrels – distance, tilt, shift, aperture. Nevertheless, there are still some slight differences, which I think are a combination of sample variation and lack of precision in the focusing scales of both lenses; infinity to 1m are barely five millimeters apart on the barrel – about seven degrees of travel, by my reckoning. Live view was used to match subject sharpness as closely as possible. Testing was done on a D800E body, at base ISO with self timer used at all times, on a locked down solid tripod – a Gitzo 5-series carbon systematic and Arca-Swiss Cube head. Whole-shot sample images were shot using the Nikon; in the A-B comparisons, the Rokinon is always the warmer image.
I think it’s necessary to start with a little background on why movements are required at all. Firstly, in all of these images you’ll notice my verticals are perfectly vertical – there’s no keystoning despite the perspective and physical camera location. This is due to the ability to shift the lens: you can effectively project a vantage point higher than your physical one by raising the optics up. Geometrically, this uses a peripheral portion of the lens to project an image onto a sensor. If you need extended depth of field beyond what you can achieve by stopping down, then the only choice is to tilt the focal plane – this extends depth of field beyond the normal distance, and in three dimensions. Imagine the imaged area – in focus, framed – as a rectangular block standing on one edge. By tilting and shifting the lens, the block can be laid down, moved up and down, and tilted. It’s a bit more complicated than that, and requires some practice to use with fluency, but that’s the gist of it.
The Nikon is a fairly familiar lens to me – I’ve used it on several occasions in the past for architectural work. Build quality is excellent, it has mostly excellent optics with a few minor qualifications, and one big shortcoming: the tilt and shift axes are not independently rotatable. The lens itself is almost entirely metal, very solidly built, is fully gasketed and weather-sealed, and has smooth geared controls for moving the axes, as well as lock knobs for securing position*. The focusing ring is perfectly weighted and well damped for precise positioning; it could use a bit more throw near the infinity limit, though. There’s an aperture ring whose position overrides the command dial selection on the camera body; it has an ‘L’ position at one end, which when selected returns aperture control to the camera. The PCE’s are unique in the Nikon lineup for having electromechanical diaphragm control only (all other Nikkors are mechanical, triggered from the camera body). This means unlike the previous 85/2.8 PC-D which stopped down with a plunger, all of the current PCE lenses require and electronic body for full functionality – unless you want to shoot wide open. They will not work properly with older bodies. It’s probably also worth mentioning that for the extra money, the lens includes the customary velvet baggie to store it in, along with a dedicated hood.
Note: on Nikon bodies with a built in flash, you can only rotate the lenses – both of them – one way and they must both be mounted with the movements at neutral: otherwise you won’t have enough clearance. Unfortunately, this also means that you can’t access the lock knob for some axes in some orientations because it’s small and directly blocked by the prism. Oddly this isn’t a problem I’ve had with the 85 PCE, but then again I think it’s because the lock knobs are further forwards.
By contrast, the Rokinon forgoes the hood but includes a slightly less-nice baggie (I don’t even think there is a hood for it) and is completely mechanical – there aren’t even any electrical contacts on the lens, which means you’ll have to use a D7000 or higher to get automated metering. It’s also got an awkward 82mm filter thread (the Nikon is 77mm). The aperture is stop down only, which means your viewing aperture is also your shooting aperture; you’ll have to add another step to the workflow in opening up to focus, then stopping down again to shoot. A little too easy to forget if you’re in a hurry, personally. Build quality is a step up from the plastic-fantastic consumer zooms, but not by much. The focusing ring has a gritty feel to it and more resistance in some places than others; the aperture ring detents aren’t very deep and easy to knock off. There is certainly no weather sealing, and though the weight suggests there’s some metal in the lens, the feel makes it difficult to pinpoint exactly where, besides the mount.
By far the worst thing about this lens is the locking and geared movement knobs for the tilt and shift axes, however. The diameter of the locking knobs is very small, so it’s difficult to bolt down securely – if left unlocked, the lens will drop to its lowest position – by comparison, the Nikon does not. Compounding this is relatively low resistance to movement in both axes and poor choice of gearing ratios, making it difficult to adjust the lens in the precise small increments required for this kind of technical photography.
But the Rokinon has one enormous saving grace: it can rotate its tilt and shift axes independently, something which the Nikon cannot do. This is incredibly useful in practice for both architecture and landscape as it means you can combine rises with tilts for greater DOF and perspective correction; the Nikon gives you one or the other. You can have the axes rotated 90 degrees at a service center, but that’s permanent and requires a new cable flex to join the two halves of the lens – something which Nikon (at least in Malaysia) are happy to charge you the better part of $400 for. This is daylight robbery on top of an already expensive lens which should just have been designed with a slightly longer cable flex to begin with, so swapping axes would be as simple as removing and rotating the back mount**. Better yet, design the damn thing so the axes rotate independently in the first place. Both lenses offer +/- 8 degrees of tilt, and +/- 11mm of shift on the Nikon, +/- 12mm on the Rokinon.
**They did it on the earlier 85/2.8 PC-D.
I think at this point it’s clear that both lenses have their strengths and shortcomings. But what about the most important part: the optics? The Rokinon runs a 16/11 optical formula, with two aspherical and two ED elements. The Nikon is a more sophisticated, but simpler, 13/10 design with three aspherical and three ED elements, plus Nano Crystal Coating and a rounded 9-blade diaphragm. The Rokinon has six blades and a UMC coating. Given that most of the time, these lenses will be used in controlled situations – i.e. stopped down and on a tripod – I didn’t bother to test wide open performance in detail; I can’t actually forsee any situation in which you’d have to shoot these wide open – unless perhaps future DSLRs have such high pixel densities that diffraction comes into play at say, f4. Consequently, most of these tests were done between f8 and f11.
Nevertheless, with all movements in the zero position, it’s clear that the corners on the Rokinon are much softer than the Nikon until f8, at which point there’s actually not a lot to choose between them. The Nikon improves a little from wide open, but it starts out already very good. It’s a similar story with near performance: both lenses will focus down to about 0.2m, which makes them good for very dramatic perspectives – though not very accurate rendering due to geometric distortion. Both lenses are excellent in the center, with the Rokinon exhibiting edge fall off until stopped down significantly; the Nikon is much, much better in this regard.
Stopped down to f8, it’s a different story. Both lenses are sharp across the frame except for the extremes; there’s a hair more CA on the Rokinon and the Nikon has better microcontrast and transmission (to be expected thanks to its sophisticated coating). Neither one does well at the edges of its image circle – i.e. the extreme movements – and the D800E is particularly revealing in this regard. I wouldn’t go beyond 5 degrees of tilt or 8mm of shift on either lens; things at the far edge start to fall apart visibly after that. It’s not coma, it’s not CA, it just appears that the lens is having trouble focusing all of the light rays to the same point. In practical terms, there’s actually not a lot to choose between them in terms of resolution and rendering style, except for two areas: color and vignetting.
The Nikon vignettes heavily at the edge of its image circle; you can correct for this, but curiously it isn’t necessary on the Rokinon. This limits practical movement distance a little more, I think. The Rokinon suffers from color casts; images are warm and hue-shifted orange. It’s not an even spectral shift either, so this isn’t something that can be corrected for via the eyedropper tool – you’ll have to profile this lens separately if you want it to match the other glass in your collection. The Nikon of course renders like every other modern N-coated, ED Nikon – high macro contrast, moderate to good microcontrast, neutral to slightly cool color, and very saturated.
It’s worth noting that in many of these cases, the lenses’ depth of field profiles do not match up
even though they were set to the same movements and focusing distances; furthermore, I also double checked the focus point with maximum magnification in live view. Miscalibration somewhere? Sample variation? Or very small movements producing noticeable effects? Possibly all three. I personally suspect the culprit is the Rokinon’s rather vague center tilt detent and somewhat loose locking screw; though when there’s movement of any sort involved in a lens coupled to a very high-resolution sensor, in a way you’re really asking for trouble.
And here we come to the crux of the problem: is the Nikon worth $1,150 more? I don’t think the answer is that clear cut, actually. There is no question, in my mind, that the Nikon is a much better built lens. It feels every bit of its price premium, and this comes through in ergonomics in use, materials and overall feel. Optically, though, whilst the Nikon is slightly better – I wouldn’t say it’s a world apart in practical use unless you’re going to use it at maximum aperture, or near it. And if you’re using an older film body, then the discussion is moot because it simply won’t work at all. Here’s the way I see it: if you’re on a budget, use a Sony or an older film body, or need independent rotating axes, buy the Rokinon and be prepared to spend some time color profiling the lens. Then tape the aperture to f8 and leave it there, and be prepared to pinch your fingers when you unlock the lens and it droops on its own. In all other cases, buy the Nikon (or take a good look at the Canon). MT
One last seat has opened up for the Prague workshop (2-5 Oct) due to a participant’s conflicting work commitments. Now available at the special price of $1,900 instead of $2,150!For full details and to make a booking, click here. Thanks! MT
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