Telescope Eyepieces, 19mm & 26mm, 1.25" dia.
Description
This project was inspired by Jerry Oltion's article in the September 2020 issue of Sky & Telescope, p. 74. These are two eyepieces for an astronomical telescope made from lens sets available from Surplus Shed (surplusshed.com). These are based on the following items: L1714 Super Plössl, 26mm fl L2075 Plössl, 19mm fl The L1714 set consists of an eye lens, a middle lens, and a field lens, all 26mm in diameter. The L2075 set consists of two achromats 14mm in diameter. I've posted more eyepiece designs here: https://www.thingiverse.com/thing:4597001 https://www.thingiverse.com/thing:4587751 Each eyepiece consists of the following parts: 1) 1.25" barrel with a 33mm dia. 1.5mm pitch external thread, 2) Housing with a matching internal thread, 3) One or more lens spacers. The L1714 has three different lens spacers, one each for the eye lens, middle lens, and field lens. The L2075 uses two of the same spacer. 4) Flexible eye guard. I made these from ABS except for the flexible eye guards. ABS is more durable, lighter, and has a less glossy finish than PLA. The eye guards are printed from black TPU The vertical resolution of the print is important to get acceptable quality on the threads. I printed mine at 0.12mm vertical resolution and a speed of 20mm/s. You can print all the parts without supports, but some files may need to be flipped 180º when slicing. I compared the image through the 26mm lens with that through a commercial 26mm Super Plössl from Meade. The 3D printed eyepiece compares very favorably to the commercial eyepiece. There's a little more distortion at the edges, and some chromatic aberration. A view of the moon shows color fringes, whereas the Meade eyepiece is color-free. Contrast is as good or better than the Meade lens, and I notice no internal reflections. The 19mm eyepiece is at least as good as the 26mm. It shows almost no chromatic aberration. The view through either lens with a 2X Barlow is spectacular.
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