Photographer Felix Steele has created a design for a 3D-printed 164mm f/2.5 lens that has no tethers or screws, uses affordable glass elements, and can be built at home for less than $15.
Steele created the design as the first major project of his online resource for open source photography projects called Pixels and Prisms. The construction includes 23 “important parts” as well as 15 pegs and is held together with nothing more than glue. Despite its simple design, the lens features a focusing mechanism and a fully adjustable aperture that houses elements in fixed tubes.
“Every photographer has different lens needs – in terms of price, speed and focal length. Pixels and Prisms The 163mm f/2.5 telephoto lens is a customizable optical system that provides an open-source, low-cost alternative to commercial lenses through 3D printing,” says Steele.
“As a photographer, the experience of building this lens has been a valuable method of connecting with the principles that underlie much of my work. When a change in lens design affects your depth of field or sharpness, you develop a keen understanding and appreciation of the equipment and techniques you use.
The finished lens provides coverage for a full-frame camera with an aperture range between f/2.5 and f/11 via a 12-blade aperture diaphragm and is designed for the EF mount.
“For less than $15, Pixels and Prisms is a viable lightweight lens option for travel, portrait or street photographers, as well as an economical entry point into telephoto photography. The aperture and zoom system can even be modified to work with any element of the lens, as long as an extender is added to the front of the optic,” he continues.
Stelle says that due to its flexibility, the lens design can serve as an accessible way to access specialized focal lengths – like 600mm – that don’t require a big investment. He says he plans to iterate on the design in the future and will work on making the form factor more practical as well as improving the optical quality.
“The process of designing and creating this telephoto lens took three months and started with the creation of an optical formula. The print files…are open for download – and the following will allow you to find and adapt a lens element to go with them,” he explains.
The only parts of the lens that cannot be 3D printed are the glass optics, and for this Steele used Surplus Shed to acquire achromatic (two-piece) lenses. He says eBay is another option, but to make this particular lens, builders will need one with a diameter of around 65mm.
“The Surplus Shed website lists a focal length next to each lens, and often Ebay sellers will include similar information. However, you’ll need to do your own measurement to get fully reliable results,” he says.
“First, balance the lens vertically (on its edge) on a table or desk. Next, place a light source on the other side of the room and point it at the lens element. The lens will focus the light to a certain point above your surface. The exact point is easily located by moving a sheet of paper to and from the lens: a halo will appear which will drift in and out of focus as you move the paper. Finally, mark the point of sharpest focus and measure the distance to the lens element. This is your focal length (although I recommend double-checking your calculation),” he continues.
“The result is a measurement that can be used to create a simple lens housing, to test image clarity and focus before moving on to the finished project. Focus your lens in front of your camera until you are satisfied with the quality of your item. You can also slide your lens down a cardboard tube. Any part that will allow you to test the performance of your lens by making distance adjustments to the sensor should work here. Once you’re happy you have an acceptable goal, set it aside and start 3D printing.
Steele says the free online Optical Ray Tracer tool is also useful for understanding the principles behind the lens.
“The software allows you to freely draw lenses and light beams, among other functions. It lets you create loose patterns of aperture and focal length – but one feature that visualizes the focusing mechanisms you’ll be working with is Zoom Lens, a preset stored in their “Examples” library.
“I chose a sample portfolio of seven images that illustrate the technical and creative potential of the lens and its excellent optical qualities,” he says.
The first is a simple shot of a lawn, which Steele includes with a version that zooms in on the middle to highlight the sharpness.
Below are the other sample images Steele captured with the 3D printed lens:
Complete building instructions for the 164mm f/2.5 Pixels and Prisms are divided into seven parts: the lens mount, the lens barrel, the external focusing barrel, the internal focusing barrel, the focusing ring, the aperture base, the opening, the opening pegs and the opening ring. After that, Steele provides the build order diagram and building tips to make building as easy as possible.
3D print files and all instructions can be found at Pixels and Prims.
Picture credits: Felix Steele, Pixels and Prisms