My review of the Rokinon 8mm fish-eye lens for the Sony E-mount (NEX) camera system.
The wide-angle dilemma
I love the Sony NEX system of Interchangeable Lens Compacts for the portability they offer compared to more established SLR systems (Canon or Nikon). These are great "travel cameras". Great as the cameras are, the lens selection is not quite up to par with what you can get for Canon or Nikon SLRs. In particular, up until now, I was missing a ultra wide-angle lens for my Sony NEX. Sony does offer the SEL1018 10-18mm Wide-Angle Zoom lens. By all accounts, this lens is a very good performer. However, at $850 at the time of this writing, the SEL 10-18mm is hardly cheap. Wide-angle lenses are difficult to make and usually command a premium, but for the Canon system, I've been quite happy with a Sigma 10-20 mm lens that is about half the price. Enter the Rokinon 8mm fisheye lens for NEX. At about $300, could this lens fill the wide-angle gap in my NEX lens collection? As we will soon see, it can but with some caveats. Now, before we go to far afield, I must clarify that comparing a fish-eye prime-lens like the Rokinon against a wide-angle zoom such as the SEL 10-18mm (or the Sigma 10-20mm for Canon) is not an "apples-to-apples" comparison. Both the Sigma and the Sony lenses are rectilinear (corrected) lenses which means you don't get the strong distortion characteristic of a fish-eye lens. Furthermore, these are zoom lenses, not primes, which can be convenient in some circumstances. Also, the Rokinon is a manual-focus lens though this is a minor issue (beyond f/5.6 to f.8, everything is pretty much in focus with such a wide focal length).
All that said, for many users (myself included) these limitations can be worked around with some post-processing and careful shooting practices. The price and size difference make the tradeoff quite attractive.
Rokinon may make affordable lenses but they do not make "cheap" lenses when it comes to build-quality. The lens is actually very well built with all-metal elements. The aperture ring can actually provide 1/2 stop increments which is an advantage over older manual lenses such as the Olympus OM lenses I reviewed in this site earlier. The focus ring is smooth, but frankly gets little use because you hardly ever need to focus with such a wide-angle lens except in some special cases (wide aperture or with very close subjects). But the most welcomed "feature" of this lens to me is it's size. I'll let the pictures do the talking here. Figures 1 and 2 show my Sony NEX-5N (since replaced by the NEX-5TL and NEX-6) equipped with the Rokinon against my "old" trusty setup: a Canon Rebel T1i with a Sigma 10-20 mm lens. The size difference is quite dramatic (and note the Canon Rebel is a "smallish" camera compared with say, a 5D MK III or a 70D). I would say that it reduces size and weight by about half which is a most welcome relief when travelling!
Though a minor aspect, I find the black finish with red circle of the Rokinon quite pleasing and a good match for a black NEX body.
Figure 1 - Size Comparison. NEX with Rokinon 8mm vs Canon Rebel with Sigma 10-20mm
Figure 2 - Size comparison
The lens hood in the Rokinon is built into the lens. This is actually a smart decision since the front element protrudes quite a bit (as is typical with fish-eye lenses) and the hood provides some degree of protection (besides the flare protection which is it's main function). One disadvantage of this arrangement though is that (as far as I know) you can't add filters to this lens so forget about using polarizers or neutral-density filters for long exposures in day-light... This is something I will miss in some cases. Let's now have a look at how the lens performs.
There's something fishy about these images
I knew going in that this type of lens produces distortion, lots of distortion. Sometimes this actually looks cool and works to your advantage. Other times, it is quite annoying. Therefore, I researched a bit on the topic of "de-fishing" software and found a wonderful plug-in for Photoshop from Image Trends. The HEMI plug-in is quite affordable and does a very good job of correcting for the fish-eye distortion. Figure 3 shows an example. Notice how the curved building straightened nicely. The resulting tilt could also be corrected further by applying the Photoshop perspective correction tools, but I left it in just to show how the plug-in works. In my opinion, It is not as good as shooting with a true rectilinear lens, but it looks quite impressive to me, with very little loss of content when the image is transformed. I reckon I can use it for my landscape photography with some post-processing. As you know, software is "lighter" than "hardware" when you travel:) This is a tradeoff I'm happy to make.
Figure 3 - HEMI plug-in distortion correction
The fridge test
How good is the Rokinon lens optically? As it turns-out it's quite good. The standard Fridge test proves it. "The Fridge don't lie:)". The "fridge test", I'll remind my readers, is the not-so-scientific name I give to a simple sharpness test I perform every time I buy a new lens. It consists of placing the lens and camera on a tripod, manual focusing on the fridge in areas of detail (papers, magnets etc) and then shooting at various apertures to see how the lens performs. Most lenses have a "sweet" spot around two-stops from wide open, so with a f/2.8 lens the sweet spot is expected at f/5.6, and with a f/4 lens at f/8, etc. The Rokinon behaved almost as per the text-book, as depicted in Figure 4. As predicted by the empirical 2-stop "rule", it is sharpest at f/5.6. What is really remarkable is that f/2.8 (wide-open) is actually very good. From f/11 onwards, diffraction effects normally degrade a lens performance and the Rokinon gets quite soft indeed. At f/22 the image has lost a lot of detail and looks very soft. Given these results, I will try to shoot within the f/4 to f/8 range whenever possible.
Figure 4 - The "Fridge Test"
Rokinon 8mm f/2.8 lens for NEX
No lens test is complete without some "real-world" results and photos. After all, the magnets in my Fridge are hardly photogenic subjects. Figure 5 was shot at f/8 and was quite sharp on my screen (hard to see in a small jpeg unfortunately). In this case, I liked the distortion effect and decided to keep it. It's an example of when the fish-eye effect actually "works" in a composition.
Figure 5 - Tower Bridge. Sacramento, California
Sony NEX-5N, Rokinon 8mm f/2.8 @ f/8, ISO 100
Figure 6 is a shot of the inside of a tunnel. This is a case where a very wide angle was needed to capture the paintings on both walls. This shot was corrected for distortion with the HEMI filter and cropped in Photoshop.
Figure 6 - Tunnel
Sony NEX-5N, Rokinon 8mm f/2.8 @ f/8, ISO 3200
And finally Figure 7 is another shot of the Sacramento Tower Bridge but this time corrected by the HEMI filter... Notice the contrast with Figure 5.
Figure 6 - Tower Bridge. Sacramento, California
Sony NEX-5N, Rokinon 8mm f/2.8 @ f/8, ISO 100
In conclusion, I'm hoping this little Rokinon lens will fill the wide-angle gap in my NEX lens collection, especially when I'm travelling and don't want to carry heavy gear. So far, I'm quite impressed with the price/quality ratio for this lens. Combined with good de-fishing software, it promises to be a very compelling solution to my wide-angle shooting needs.
Comments, questions, suggestions? You can reach me at: contact (at sign) paulorenato (dot) com