Text and pictures © 2005-2015 Guillaume Dargaud
Last updated on 2014/01/14
"Best wide-angle lens ? Two steps backward." — Ernst Haas (1985).
Left: Aerial view of Concordia. I attached the camera, pointing vertically down, to two tethered helium balloons normally used to launch radiosondes into the higher atmosphere. I let the balloon carry the camera to about 50~80 meters, using the timer delay to trigger. In this case I used the fisheye lens not for the 'round effect', but for the fact that previous trials had shown it was very hard to control the direction and the framing of the shot. In this case, if it points more or less down I'm sure the building will be in the shot.When I purchased this Sigma 8mm/f4 in 2004 I didn't have a precise idea what I was gonna do with it. Fisheye lenses provide very specific images that you cannot easily mix with other images, so it's better to have a precise purpose when using one. Shortly I found plenty of possible applications. Among them:
Left: Another aerial view of Concordia.
Right: An example showing the use of a fisheye lens to take a picture of a round object, in this case a duct opening (okay, this is not perfectly framed, but you get the point). Claire inside a water recycling tanks, cleaning the mud from the bottom. See and compare the similar straightened image farther down.
As you see, several of those applications need extra work with respect to a normal image, and cannot be shows directly as slides. This lens is meant for a traditional 24x36 Nikon, but I've also used it on a digital Nikon. In that case where you still have 180° (actually 177°) of horizontal field, but the top and bottom parts of the image circle are truncated to about 120° of field which is enough for most applications, including straightening. The edge of the image circle is not very sharp and also darker (vignetting), but it's not an issue when assembling 360 panorama (I recommend taking 6 horizontal shots and 3 vertical for a full 360x180°, removing yourself from the frame). Overall I was surprised to use this lens a lot more than I'd have expected. An addiction to wide angle photography can quickly turn into an overdose with this one !
Note that if you want to use a full-circle fisheye on a digital SLR with a small sensor, there is only one choice: the new Sigma 4.5mm f/2.8 EX DC HSM Circular Fisheye Lens (also available for Canon and Sigma mounts).
Left: Another view of a circular object, here a ladder with protective circles, descending into the frozen hell of the seismology cave.
The images shown in this section, I left 'as is': a 22mm circle on film, showing an angle of 180° across the diagonal. One characteristic of images like this is that angles are maintained. What is at a 30° angle in the scene is also at 30° on film, which is not the case of images taken with a rectilinear lens (basically every other kind of lens). This can have scientific or technical applications. See below for other ways to transform and display fisheye images. On the other hand, straight lines are no longer straight. It's the age old problem of drawing the surface of a sphere on a flat sheet of paper (67 different projection methods have been invented that I know of).
Right: Pointing the camera vertically up allows you to take the entire sky and whatever sticks out of the ground. Lay down in a hole if you don't want to be seen.
I find that in most cases 'round images' like this are not all that appealing to look at, but there are exceptions: the sky can be shown in full the same way you'd see it if you were simply laying on your back (drunk or not). Also taking images of round objects up close, such as a duct opening, can be interesting. Note that there are several kinds of fisheye lens: the one I have is an 8mm and provide a 180° field on a 22mm image circle on film. Others are 14 or 15mm and provide a 180° field across the diagonal of the film, so you don't see the circle. And finally there's the legendary Nikon 4mm, costing an arm, a leg and a few other body parts with a 6 month wait list on ordering, which provides an insane 210° field across the 22mm image circle; yup, this lens can see behind the camera !
Left: Note the strange flare effects on this image. When taking pictures with a fisheye lens, half the time you'll have the sun within the frame, so you'd better bet used to have some flare.
Right: Stars rotating around the south stellar pole on this 2 hour long exposure.
Left: The ConcordiAstro platform seen from below, legs fully extended.
Right: Installing the Meteoflux mast. I find that the eye takes a while to get used to circular images such as this one, that's why I grouped them together before showing the straightened and unrolled versions.
Left: Parhely, anthely and all kinds of halo circles are visible with the sun hidden to avoid excessive flare.
Right: The Milky Way seen through over the 180° horizon of the Dome C sky. The camera was tied to a telescope to allow for a few minutes of exposure. The telescope is visible on the upper left of the image and the band next to it is a faint aurora. Then the two white blurs are the two Magellanic clouds. The dark area on the Milky way is called the Coal Sack and is a typical southern hemisphere feature, quite visible to the naked eye. The reddish lower part is light from the sun, still way bellow the horizon but shining nonetheless. More info about antarctic astronomy.
Left: Shot with very little space and lots of pipes everywhere, this picture was straightened to hide the fact that I was less than a meter from the subject.
Right: Another small space shown much larger than its real 4 square meters.
After using this lens for a while, I often felt the need to straighten up the images. In many cases it's pretty obvious, for instance you take an image with vertical lines and they all end up curved towards the middle at the top and bottom of the photo. A formula similar to what I've used in my old PanoWarp program can take care of that, so I wrote a variant of that program, still freeware, only for full-frame fisheye image correction. Sometimes it works great (particularly when the camera was held perfectly horizontal), other times the original image is better.
Left: When taking pictures with 180° of field it's often difficult to avoid having your feet in the shot. Here the problem is reversed on this self-portrait where I'd like as much of myself (holding the camera) and the back ground as possible. Unfortunately this is still not enough.
Right: Scary, ugly or funny, this kind of portrait tends to get old quite fast...
Here are a few examples of 180° images which have been straightened in software. What was on the left half of the image circle is now the left side of the image, and the same for the right side. The vertical and horizontal lines in the middle of the image are left untouched and the top and bottom are the most stretched parts, often requiring a cropping of the image. Basically, starting from a fisheye image, you get a very approximative rectilinear image (technically it's not true).
Left: Showing the way down to the ice tunnels and the seismology cave.
Right: Yet another image taken in a minimal volume and straightened with FisheyeWarp.
Left: Playing with the perspectives with this image taken with the camera on the ground, pointing up and the wooden door rotated sideways.
Right: Identical settings, but the camera has been moved by a meter, showing a major perspective change.
Left: Sandro at the controls of the summer camp radio room.
Right: Working to complete installation of a Concordia bedroom.
Left: Another fisheye portrait, with an even more dramatic angle. The main difficulty is lighting as usually one side is darker than the other. This time the picture is taken from a digital camera (Nikon D70), notice how the image circle covers the full height of the frame bu only about half of the width.
Right: How to keep warm ? A wrestling match in the snow ! On this image the horizon wasn't in the center of the image, and thus stays curved even using the straightening algorithm.
Above: Aerial view of Concordia taken from a tethered balloon.
Above: Another aerial view of Concordia. On both images I made sure the horizon would stay a straight line, even at the expense of leaving extraneous black on the image.
The above method worked great when the camera is pointing horizontally, but what about when it is pointing vertically, either up or down ? Well, a similar mathematical formula (actually the same one but with different parameters) can 'unroll' the image into a panoramic image: you now see 360° horizontally and 0 to 90° vertically. The perimeter of the image circle turns into the bottom of the panorama and the center of the circle is stretched across the entire top of the image, which is then better cropped unless you use it with a spherical viewer (like a Java applet).
Above: The milky way above Concordia, with a halo circle around the moon. [Enlarge your browser for full view]
Above: Long exposure, unrolled into a panorama keeping the horizon as a straight line.
Note that you don't necessarily have to use the image center as a reference point for the transform, you can also use the 'logical' center of the image. For instance if the camera wasn't pointing perfectly vertical you get only part of the horizon near the image perimeter; you can use that horizon as a reference to ensure it will be straight on the resulting panorama. I've played with this capability by pointing the camera at the south stellar pole, letting the stars rotate around, and then unroll the result leading to straight moving stars but a sickening sine-wave horizon as bad as a furious sea (or the next San Andreas hiccup).
Above: Long exposure similar to the previous image, but this time centering the unrolling in a way as to keep the stars into straight lines. The horizon is waving.
Above: The circles made by the stars rotating about the celestial pole are turned into strange shape by the projection method used. A stellar maelstrom ? The endtimes come early today.
Above: With a shorter exposure time, the weird effects above are all but invisible and the Milky Way shines in all its splendor.
Above: An image of the Lidar shooting at the sky from the Atmosphere Science container, with the Milky Way and the two Magellanic clouds clearly visible above (one is on the far right and one on the left).
Above: An image of the Lidar shooting at the sky, with the Milky Way and the two Magellanic clouds clearly visible above. I had to stay static for several minutes to appear in this dark outline. A shooting star is visible on the left edge of the image next to a Magellanic cloud.
Above: Another image of the Milky Way with Concordia and ConcordiAstro below.
Above: We need you in Antarctica... An image taken with the camera on the ground, pointing straight up. Only things sticking out of the ground are visible, as well as a perfectly pure sky. On this image I hid the flares with some photoshopping.
Above: Similar image, being careful to place the camera in the shade in order to avoid flares.
And finally a more general transform method can be used to transform a fisheye image into any kind of angular transform. My little FisheyeWarp freeware doesn't cover this but if you are interested you can try it with PTgui.
In particular, this same PTgui allows you to assemble several fisheye images into a full 360x180° spherical panorama with a minimum of 5 images. Here's just one example, but I have many more panorama examples taken with that same 8mm lens. Most of the images shown here were taken during the first winterover at Concordia station, on the high Antarctic Plateau. Just to say I'm pretty happy with that purchase even if the sharpness is not up to what I get with my 20mm for instance.
Above: The summer camp panorama assembled from 3 fisheye images. The top and bottom parts have been cropped to keep the vertical view to 120°.