When is a Fisheye Not a Fisheye?
Do you hate the fisheye look, or maybe just moderately dislike it? I do… and the more exaggerated the look the more it isn’t for me. But, there is a lens that I recently discovered that creates a 180 degree horizontal field of view with only moderate rectilinear distortion. After using appropriate image process technique, it can produce images that are even good enough for some architectural use.
This lens is a 12mm f/2.8 full-frame fisheye lens of stereographic design, made by Samyang, and sold under that name as well as under the Rikonon name. These lenses are identical and from the same factory. Only the branding differs.
The one I purchased is the Rokinon 12mm f/2.8 ED AS IF NCS UMC Fisheye Lens for Sony E-Mount. It is available in Sony E, Canon EF and Nikon F mounts. It is manual focus, and in Sony and Canon mounts has no electronic connection to the camera. In Nikon mount aperture information is transmitted and can be controlled by the camera. In all mounts, there is a traditional aperture ring. There is no intermediate stop between f/2.8 and f/4, and then there are half stops between f/4 and f/22.
The focusing ring turns about 120 degrees between infinity and 0.6 feet, its closest focus distance.
The lens is supplied with a lens shade, which also serves as a mounting point for a solid plastic lens cover. This is critically important because the front element protrudes quite a bit and is exposed to accidental bumps and fingerprints. The hood attaches and detaches quickly and securely.
Mechanically this lens feels solid, and is well designed, though given its low price point of USD $499 (from B&H Photo), it is not of the material calibre of top-tier lenses from major manufacturers. But, it certainly doesn’t feel cheap or flimsy.
Optically though, it’s a different story. This lens is nothing short of excellent optically. The design consists of 12 elements positioned in 8 groups, with three low dispersion ED glass elements and two of the elements are aspheric. As mentioned above, this lens is a stereographic fisheye. What this means is that unlike fisheye lenses that produce round images, the entire surface of a full-frame sensor is covered, and a field of view that is 180 degrees horizontally is produced.
The stereographic design aspect means that the corners of the field of view aren’t highly compressed, and so the perspective rendered is quite pleasant, with horizontal straight lines having only moderate curvature.
The lens isn’t magic though. The edges and corners are definitely softer than the centre – which is of prime lens quality. If soft corners aren’t acceptable for your uses then you may not regard this type of lens as worthwhile.
A First Example
The frame above is a sample interior architectural shot, processed normally in Lightroom, but with no correction for the lens’ unique characteristics. It was a single frame, taken hand-held. Balancing of the interior and exterior brightness was done using the tone controls in Lightroom CC.
Care was taken to ensure that the camera was horizontal, using the camera’s built-in level indicator.
Immediately above is the same frame, but with correction optimally applied using Photoshop and an inexpensive plug-in called Fisheye Hemi, which costs about $30 – for Mac and PC. This plug-in isn’t completely necessary, because almost everything that it does can be achieved manually in Photoshop, but it does make the task quicker and easier.
The definitive article on this is by Ian Norman from Lonely Speck. If you read it, and also watch his Youtube video you’ll have all the information needed to defisheye just about any such lens. Be aware though that not all fisheye lenses are created equal, and that the Samyang / Rokinon 12mm f/2.8 for full-frame cameras is a special beast and it corrects extremely well much of the time.
As Ian points out, defisheyeing can be done using basic tools that are found within Lightroom and Photoshop. But, while quick and easy to use they may not produce very good quality. Edges can become blurred and often quite a bit of the extreme coverage of the lens is lost.
If you have Photoshop the best tool to use is the Warp Tool. The first thing to do is process your raw file in Lightroom as you normally would, for white balance, tonality, sharpening etc. Now, export to Photoshop CTRL-RIGHT CLICK / Edit in Photoshop. Be sure that you have your Lightroom preferences set to export in 16 bit TIFF.
Once the file is in Photoshop create a new Layer from the background. Next select EDIT / TRANSFORM / WARP. Turn on Rulers and Grids (but not with too fine a grid pattern). Then, zoom out a bit. Your screen should now look something like this.
You’ll next proceed to grab some of the anchor points (or even objects within the image itself) and adjust the look until it is normalized. There is no set of rules for this…it’s all freehand…depending on the subject and whether the camera was horizontal, or pointed upwards or downwards.
As with my example here, where the cameras was both level and at 90 degrees to the ground, the adjustments needed are relatively minor. This tool is one where usually less is more.
When done, press RETURN. Depending on how strong the adjustments needed were you may have to crop the image a bit, but usually very little of the lens’ extreme wide angle coverage is lost.
Finally, flatten the image’s Layer(s) and then Save. You’ll be returned to Lightroom with the adjusted image loaded into your Library with -EDIT appended to the name.
One More Thing
At the moment (October, 2015) I believe the Rokinon 12mm f/2.8 to be best choice in an ultra-wide lens for Sony full-frame E-mount cameras. This is taking into account angle of coverage, aperture and price.
But, just as this is being published Voigtlander has announced three ultra-wides in Sony E mount; 10mm, 12mm and 15mm. Exactly how these shape up as alternatives to the 12mm Rokinon will be seen once these new Voigtlanders ship in Spring, 2016.