Distortion of linear perspective and cognitive load.

While it is much easier to justify the use of a diagonal fisheye lens as a means of expression, the use of a circular one requires a more compelling reason.

Another issue is that while there are quite a few diagonal fisheye lens designs—and new ones are constantly appearing—there aren’t that many circular ones. Especially if we want to buy something at a reasonable price. We have the AstrHori 6mm f/2.8 with E, RF, Z, and L mounts for full-frame cameras, and we have the 7artisans 4mm f/2.8 for APS-C (E, FX, EOS-M) and M43. The former has a list price of $299, and the latter is $149.

Today I’m going to take a look at the tiny 7artisans on the Micro Four Thirds system. It’s tiny, which is all well and good, but it does come with certain drawbacks. If you attach it to a PEN, it’s fine. However, when attached to an OM-1, it will catch the body’s grip in its field of view and be visible in every shot. Another issue is taking photos with a 225-degree field of view and how you hold the camera. With a larger body, holding it at a certain distance from yourself whilst pressing the shutter button requires a fair bit of dexterity to avoid capturing your own fingers in the shot. It’s a whole lot easier with the little PEN. What does our little one look like?

I’ve seen comments saying that the lens cap doesn’t stay on properly (it’s a slip-on type) and can fall off. Mine fits snugly and slides on and off with just the right amount of resistance. The lens itself features a 7-blade aperture ring with a range from f/2.8 to f/16, and a declicked mechanism. A small grip is screwed onto the ring; whether this is helpful or not, I’ll leave that for you to judge for yourself. It might be useful when filming, but when taking stills, as you can’t hear the aperture clicks and, what’s more, you can catch the lever and move it… . There are no contacts transmitting information to the camera body, so the photo will be taken at whatever aperture you set it to; it’s therefore best not to increase the margin of uncertainty.

The lens is very sharp in the centre, but the physics of the 225-degree field of view result in loss of resolution and spherical aberration right at the edge of the circular frame. There are several important considerations regarding the geometry of the image circle inscribed within the sensor’s rectangular area. Firstly, the lens was designed for APS-C sensors; when an MFT camera is used, the image circle will be very close to, or even right on, the very edge of the sensor. Contrary to what you might read on various websites, never, ever switch on image stabilisation. There’s a very high chance the image will move out of frame. This is particularly true when filming. Unless, of course, you like the effect of a circular image moving off the left or, for example, the right edge of the screen. Another issue associated with the characteristics of a lens of this design is flare, reflections and bright circles around the image. It’s impossible to avoid them. Personally, I love the effect they create; they really add to the atmosphere.

I’ve seen photos where the photographer completely cropped out everything happening outside the frame. To me, that looks flat and lifeless. There can be so much going on seemingly outside the frame itself, yet in reality, it’s what gives the frame its meaning. This raises the question of how to crop a photo, because, after all, we save rectangles as files. It’s incredibly cramped in MFT. So leaving plenty of space on the right and left will emphasize the lack of space at the top and bottom. A square format won’t work either, because we might lose some detail on the sides. The light outside the image circle can also dance around at varying distances. I’ve adopted the rule that I crop images with a height of 3456px to a width of 3656px, which gives a ratio of 1:1.058. It’s almost a square, but it usually doesn’t ruin the highlights on the sides too much. However, if you’d like to print a photo taken this way—on a black background, such as in a photo book—it’s worth considering not cropping the frame, completely blacking out the background outside the image circle, and carefully handling the flares in post-production. Just like in the example below.

The perception of an image captured by a circular fisheye lens is based on the disruption of natural, learned mechanisms of vision. The extreme field of view (often in excess of 180 degrees), compressed into a circular frame, forces the human brain to perform non-standard cognitive processing.

The main psychological and cognitive factors underlying this phenomenon include:

Distortion of linear perspective and cognitive load.

Throughout life, the human visual system learns to interpret space on the basis of Euclidean geometry – the brain expects vertical walls and the horizon to be straight lines. The extreme barrel distortion characteristic of a fisheye lens forces the viewer to constantly reassess curvatures. This results in a higher cognitive load and, in some people, causes mild visual-vestibular dissonance, leading to a sense of disorientation or sometimes even dizziness.

Forced focalisation (attention tunnelling).

In an image taken with a circular fisheye lens, the centre of the frame remains relatively free of distortion, whilst objects placed there appear unnaturally close and large. The edges, in turn, are extremely compressed and curved. Such a geometric structure inevitably draws the viewer’s visual attention to the centre. This phenomenon gave rise to the psychological metaphor of a cognitive bias known as ‘Fisheye Syndrome’, in which the brain prioritises what is at the centre of attention, completely marginalising the background and periphery.

The effect of voyeurism and surveillance:

The black border surrounding the circular image on a flat screen is immediately reminiscent of looking through a door peephole, a microscope or a CCTV camera. From a psychological point of view, this places the viewer in the role of an outside observer, a voyeur. It evokes specific emotions in the viewer: ranging from a sense of being trapped and claustrophobia, through intimacy, to paranoia.

Subjectivisation and a sense of unreality.

A standard lens (e.g. 50 mm) simulates an objective, ‘human’ perspective. A circular fisheye lens distorts proportions so drastically that the brain automatically categorises such an image as extremely subjective or originating from an ‘alternative state of consciousness’. This distortion heightens the sense of chaos, madness, hyperactivity (often used in music videos or sports footage) or the protagonist’s isolation within their own, closed ‘bubble’.

There’s at least one more use left. Astrophotography, star trails, and nighttime lights. I don’t usually bring this topic up very often, because it’s both dark and cold then, but I do have two examples.

Circular fisheye lenses aren’t exactly everyday lenses. The 7artisans 4mm f/2.8, however, is a lightweight lens. The manufacturer lists its weight as 201 grams. I usually carry the lens with both the front and rear caps on. When weighed this way, it comes to 239 grams. That’s still light enough to carry as an extra piece of gear—just in case the right subject comes along.

A major problem is accidentally capturing parts of yourself in photos. Feet, legs, hands… Forget about a tripod—it’s a 225-degree angle, and you’re looking behind you. Taking a photo means pressing the button with your fingertip while keeping your arms straight and extended in front of you. Shooting from a lower angle means there’s a good chance you’ll end up with your own forehead in the shot. But all in all, it’s great fun and a lot of enjoyment.

It worked perfectly for me during my trip to the Naples area, which is why I included a few examples above. It works great when you need to capture something to highlight its uniqueness.

Another way to use it is in video sequences depicting “escapes from the zone.” But that’s a story for another time…

Just to be perfectly clear: 7artisans does not sponsor me in any way, and the lens described here is one I bought with my own money.