Eyepiece Turret for the Hadley Telescope - Find your target and zoom in seconds.

Are you annoyed when you switch eyepieces to take a closer look and have to adjust the Focuser every time, and sometimes lose your target? Try the Turret: set the focus for each eyepiece once and leave it be! Much easier, and more time to enjoy the planets and the stars. This Turret for the Hadley Telescope holds three eyepieces in a parfocal plane. With it you can switch between magnifications in seconds, without refocusing or losing your target: Find the target with a smaller magnification eyepiece (like 25 mm) Look at the details in larger magnifications (6, 9 or 10 mm) 📷 Image redacted — claim this model to add your own media It takes about 8 hours of print time and a couple of minutes of assembly. Let me know how it works for you in the comments. Key features The design fits on the existing Upper Tube Assembly Individual eyepiece focusers enable parfocal function (see section below) Easy, low force twist operation with accurate eyepiece repositioning Angled design to keep the other eyepieces clear of your head (see pictures) Other aspects Tolerances and part sizes are suitable for any normal 3D printer 2 mm pitch threads for fine adjustment, still prints well The Snap Hook is a small separate part to adjust the lock snap feel to your liking Imperial and Metric versions BUILD INSTRUCTIONS Additional parts Imperial: #10 x 2 inch machine screw & nut Metric: M4 x 50 mm machine screw & nut Printing instructions I used matte black PLA for most parts. The threads, assembly and moveable interfaces in general have 0.1 to 0.3 mm clearances, which works well on my Prusa Mk4 printer. Turret Assembly parts Turret, in PLA, default setting, use scarf joints Base Plate, in PLA, default setting, use scarf joints Top Ring, in PLA, 100% infill The Base Plate and Top Ring are specific for either Imperial (#10 screws) or Metric (M4 screws) Snap Hook Pick one, start with Light Print In PLA, 4 perimeter layers Eyepiece Holder parts 3x Short or Long Eyepiece Holder: in PLA, default setting, use scarf joints 3x Focus Lock Ring: print at 0.15 mm layer height in PETG (to avoid sticking over time). I printed mine in three colors to keep track of the positions and associated Eyepieces 3x Eyepiece Lock Rings if using the Long Eyepiece Holder, at 0.15 mm layer height Optional Nice to do but not needed, black out the surfaces in the optical path: inside of the Base Plate insides of the Turret (but not the threads) inside of the Eyepiece Holders Determining Which Eyepiece Holder to use For background The original Hadley Focuser has an effective focus adjustment length of 50 mm. This design has an adjustment length of 30 mm to make it fit on the UTA and not change the optical path length. To achieve the same 50 mm adjustment range it has a Short (0 to 30 mm) and Long (20 to 50 mm) Eyepiece Holder. Steps to determine the Holder You can use your existing Focuser to determine the right Eyepiece Holder to start with: Keep or set the existing Focuser in focus Measure the distance from the top of the Focuser to the base of the Focus Plate (see picture below) Subtract 53 mm Determine the right Holder: 0 to 30 mm: Short Eyepiece Holder 20 to 50 mm: Long Eyepiece Holder For example, from the picture: 71.6 mm - 53 = 18.6 mm, therefore Short Holder Notes The Eyepiece Holders are designed for a 31.60 mm to 31.75 mm eyepiece interface diameter (which appears to be pretty standard for 1¼ inch eyepieces). The Short EP Holder holds the eyepiece with a snug press fit. (It is secure, still figuring out a locking mechanism that does not interfere with the adjustment length). The Long EP Holder has the same press fit, and an additional Locking Ring to secure the eyepiece. If your eyepiece is loose or tight let me know and I'll make a tighter/looser version. 📷 Image redacted — claim this model to add your own media . 📷 Image redacted — claim this model to add your own media . 📷 Image redacted — claim this model to add your own media . Focuser measurement Short Holder Long Holder Assembly instructions See below for the cross section of the full assembly. Assemble the Turret Assembly Put the Turret on the Base Plate shaft Orient the Top Ring: there is a small step on one side of the Top Ring. Orient it Down for a clearance fit (turret spins freely), Up for a tighter fit of the turret. Put the nut in the bottom hex hole and put the screw in place (hand tight) Put the Snap Hook in the square slot (loose fit, held in place when placed on the UTA) Assemble the Turret Assembly onto Hadley Remove the original Focuser from the UTA Put the Turret Assembly on Put the 4 machine screws back in (twist the Turret to reach the two holes underneath it). Install the Eyepiece Holders Put the Focus Lock Rings on the Eyepiece Holders. Thread the Eyepiece Holders onto the Turret; the initial fit is a bit stiff, but it smooths out with use. Push your Eyepieces in place It should be a nice press fit. 📷 Image redacted — claim this model to add your own media Cross section view of the assembly Parfocal Focusing instructions The major benefit of the Turret is setting and leaving all eyepieces in focus. Here is how to achieve that: Step 1: Rebalance Hadley Put all Eyepieces in place move the Mount Interface per the Hadley instructions. Step 2: Test and set initial focus (in daylight) Find a distant target (per the Hadley instructions) Twist the Eyepiece Holder to adjust focus Twist the Focus Lock Ring while holding the Holder, to lock it down Repeat with the other two Eyepieces Step 3: Final focusing at night Find a bright target star (Iike Sirius) I highly recommend using the Bahtinov Mask Focusing Device by attenuendo Twist the Eyepiece Holder to adjust focus Twist the Focus Lock Ring down to lock it, while holding the Holder Repeat for each Eyepiece USE Unlock the turret out of it's locked position with a little squeeze. The eyepieces can be removed for storage without unlocking the Focus Lock Rings. Just put them back in the next night, it shouldn't take much refocusing if any. Keep track of each eyepiece and the associated position number, I printed the lock ring in different colors for an easy reference Creator's notes The design is inspired by the nosepiece on a microscope. I considered making an integrated version that replaces the UTA part, but this version works well. It requires less printing, and it is more compatible with existing telescopes. I might still do it as a separate design at a later date; the main benefit is having a single eyepiece holder with full 50 mm adjustment range. Hadley is a fun thing to design for, check out my other designs in Redlow's Hadley Add-Ons Collection Change Notes Version 1.0 - 10 Feb 2025 Original version Version 1.1 - 12 Feb 2025 Added metric version, very light Snap Hook Version 1.2 - 14 Feb 2025 Updated both Lock Rings with increased thread clearance Minor update to the Turret, added tactile features to make it easier to unlock by touch