For the sake of order, I’ve collected here some example of homemade solutions and links for the wide macros. The list is far from complete!
Standard wide angle spaced
The most intuitive way to get a a wide angle focused near is to take a normal wide angle lens and add some more back distance to the sensor, typically with macro rings or bellows. Lenses aren’t usually image telecentric, so some field is lost when focusing closer. This issue can be worked around by using a wide lens designed for small format (APS C) onto a larger sensor (35mm). This setup works up until about 1:1, when either the subject is so near to hit the front lens, or the crop gets too narrow to be called wide angle, or the image quality falls off significantly.
According to the practitioners and their photos, image quality is excellent, almost at the level of the original lenses. With correct lens and macro ring, autofocus and aperture control can be retained.
Some examples Charles Krebs and from Nicky Bay
M12 fisheye with macro relay
In the years 2010- 2015, it spread the fashion to use small fisheye lenses, typically M12 board objectives, mounted over a macro lens, who does the job of a relay system. I could not find who has been the originator of this technique, and anyway as Savazzi said, combining lenses in any imaginable assembly has been experimented since the first telescopes.
This specific probe combination proved very effective, allowing strong magnifications and field of view up to to 180 degrees (possibly a little more!). M12 lenses are widely available at very low factory prices and provide respectable image quality; they are rated for the # of megapixels they support, and can (claim to) reach up to 16 MPx. The intermediate image is of small size (typically designed for 2/3″ sensor size or smaller, about 11mm of image circle) so, paired with a 1:1 macro for relay, will not fully cover a 35mm sensors nor APS, so it needs more secondary magnification and/or digital cropping. The most common relay lens used is a native macro objective, which offer autofocus and aperture control, with magnification enhanced by spacers and close up lenses. Use of the M12 lens in direct projection is difficult, due to its small size and short focal length.
M12 fisheyes and rectilinear wide angle lens have retrofocus design, so their maximum magnification is physically limited by the minimum working distance, with the entrance pupil buried inside the lens, and all aberrations coming from their use outside the design optimum. Beside fisheyes, wide-angle pinhole lenses have been used also, giving a bit more working distance but less angle and corrections. Below the setup from Shinchin of photomacrography 2012; the relay is taken care by a JML 21mm macro lens (5) held in the tube by the thumbscrews, which provides about 4:1 magnification. (1) is the small fisheye.
An extensive explanation by John Hallmen, with a 2,1mm f/1.6 M12 fisheye lens in front, an inverted 24mm with spacers as relay lens.
Again Nicky Bay is very prolific on the field with this setup; 2x native macro + diopters as relay.
Put a wide angle adapter in front of a macro
Maximilian Simpson on a 35mm format camera tried several combinations, and ended up with a short manual macro (28mm fl) with some spacers, widened by putting right in front of it a negative meniscus lens pillaged from a zoom in front, as wide-angle reducer. He found this add-on lens giving wider view and better quality than conventional reducers. See Petapixel article and his webpage . The images looks good and the system is very compact; max magnification is again limited by the lens touching the subject. He measured the angle of view at a good 92 deg (long side) and magnification 0.92:1
Documentation websites
It is incredible what people can put together with years of passion. Only English and Italian sites, the rest of the world is still mostly unexplored.
Comprehensive set of articles about scientific macro by Enrico Savazzi
Macro Lens collection database by Klaus Schmitt
Rare details and schemes of film era lenses by Marco Cavina
Photomacrography.net, where the new methods are developed and shared
Tough optics and how to tweak microscope objectives, made easy by “The Pensionists Club”
Half cooked dreams by Giorgio Pattarini 