Here’s a better example of the spherical distortion I mentioned. You can see in the subtle bokeh in the background that it swirls in a circular way, where the edges are a little more in focus than the centre.
This means you can separate a central subject more effectively from a background and do so in a unique way. Modern lenses have the focal line run perfectly perpendicular to the camera. In this case the line is curved, running a little further on the edges and a little closer in the middle.
Bit of a creepy title but it’s a bit of a creepy photo. Again, not a clue what plant this is but it looked cool so I clicked the button and made this.
The distortion is done by my favourite thing – foreground subject blur, where the thing is so close to the camera, the light from the actual subject can get around it and hit the sensor, albeit a little distorted and bent. Aperture needs to be open for this to work – F2.8 here.