About the Tarsier
The Tarsier is Lunatico's focuser controller hand unit, built to adapt to almost any focuser motor on the market via a custom-made mounting plate—it isn't limited to Seletek motors; other motors can be used as well. It isn't the classic small controller with two buttons and a dial—the Tarsier has six buttons and an LCD screen, and those additions push its dimensions to 90 × 145 mm, noticeably larger than a typical two-button unit. The reviewer noted this size becomes a practical issue when mounting the controller itself: the power and control (DB9) connectors sit on top, making it awkward to hang from anything, and there is no hook or cord included. Velcro straps, or an improvised mount fixed to the tube or mount, are the recommended workaround. The integrated hand controller does mean the Tarsier can be used standalone without a laptop, though it does need external 12V power—there's no internal battery. The DB9 cable supplied is fairly long by default; the reviewer recommends a shorter male/female DB9 cable if you're using it at the eyepiece for visual work. An optional temperature-control add-on is also available for deep-sky astrophotography work.
| Dimensions | 90 × 145 mm (larger than a typical two-button controller) |
|---|---|
| Motor modes | Full step / Half step |
| Speed settings | Multiple, adjustable |
| Position memory | Manual list of eyepiece positions—must be saved via long-press MENU before power-off |
| Compatibility | Works with most focuser motors on the market |
Key features reviewed
Focus position memory
The Tarsier lets you build a list of saved focus positions—one per eyepiece, for example. During testing, the reviewer memorized positions for a 35 mm eyepiece (944 motor steps), a 20 mm eyepiece, a 9 mm Baader Ortho (2681 steps), and a 9 mm Ortho combined with a 3× Barlow (6035 steps), saving each by holding down the OK button after finding focus. Once saved, switching between eyepieces—or swapping in a Barlow—means you can send the focuser to the right position while you're still changing optics, rather than hunting for focus from scratch each time. This list is not retained automatically, though: before disconnecting power, you need to hold down the MENU button, which prompts a confirmation that the list has been saved. Skip that step and the list is gone the next time the Tarsier is powered up.
Adjustable speeds
Speed is adjustable from 0 to 100 ms/step, letting the user slew quickly to the target focus region and then switch to fine, slow movement for critical focus. The reviewer settled on 7 (fast) for coarse acquisition and 15 (slow) for fine adjustments during a session.
HalfStep mode
HalfStep mode doubles the effective resolution of the stepper motor by activating half-step drive sequences, reducing vibration at high magnification—the reviewer tested it in the 100×–333× range, where it gives noticeably finer control than full-step operation.
HighACC—single-tap fine focus
A discrete single-tap mode for critical high-magnification focusing: each button tap moves a small, fixed number of steps rather than a continuous slew. The reviewer's preferred value was 12 steps per tap.
The Astronomía reviewer particularly liked being able to save a position for each eyepiece and jump between them without hunting for focus in the dark—especially useful when refocusing through a Barlow lens, where the point of best focus is otherwise hard to judge by eye.
Conclusion
The reviewer's overall verdict was positive: near-universal motor compatibility makes the Tarsier useful for visual observing as much as for astrophotography.
From the review
Photos from the original test, showing the Tarsier and its Seletek stepper motor fitted to a 200 mm f/5 Newtonian on an EQ6 mount.
