Troubleshooting & FAQ

Note

This page applies to rev4, v3 and v2.5 PiFinders running software 2.2.0 or above. If you’re on older software, updating is often the fix in itself — see Update Software.

Not sure which you have? See Which PiFinder do I have? in the Quick Start.

Most PiFinder hiccups have a quick fix, and the cause is usually something simple — focus, or a settings mismatch — rather than a fault. This page is organised by symptom: find the line that matches what you’re seeing and follow it to the cure. If your symptom isn’t listed, or a fix doesn’t sort it out, the PiFinder community on the Discord server is quick to help.

The PiFinder won’t turn on

Power is the button marked PWR, on the front below the keypad. Press and hold it for about two seconds to switch the PiFinder on — the PWR label lights while it boots. Press and hold it while the unit is running to bring up the shutdown confirmation. (The SQUARE key never controls power.)

Things to check:

  • Is the battery charged? Plug a USB-C cable into the POWER port — the CHG light comes on while the battery charges. Once the PiFinder is running, the title bar shows roughly how much longer it will run; see The battery indicator.

  • Try a different cable and supply. Some USB-C cables are unreliable at the current the PiFinder draws. If it runs on external power but not on battery, the trouble is the battery, not the computer.

If none of that helps, hold the PWR button down for more than 14 seconds. That resets the power system itself rather than the software: it cuts power to a unit whose software has hung and won’t shut down, and it will let one power on again when something is stopping it from starting normally. It’s a hard cut rather than a clean shutdown, so keep it for when the PiFinder is genuinely unresponsive.

Note

On v3 and v2.5 PiFinders, power is a small white slide switch — it slides side to side, not a push button. Facing the screen, slide right for on, left for off. There’s no battery indicator on a v3, so plug in to charge if you’re unsure; the charging light glows blue while charging and green when full. The port closest to the keypad powers the unit immediately, regardless of switch position, which is a quick way to tell a flat battery or a failed switch from a dead computer. If you built your own unit and it won’t power up at all, double-check the PiSugar battery board connections. The v3 manual covers that hardware throughout.

The screen is blank, or it won’t finish booting

Rule out the simple explanations first:

  • Brightness turned all the way down. If the PiFinder was last used at a dark site, the screen may be dimmed to nothing. Hold SQUARE and tap + several times to bring it back.

  • Give it time on the first boot. A normal start-up reaches the welcome screen in about 20 seconds. The first boot after re-imaging takes a minute or two and restarts itself several times while it sets up — that’s expected. Wait a full five minutes before deciding something is wrong.

If the screen is still blank, the keypad backlight tells you where the problem is:

  • No keypad light and no screen (a faint red LED inside the case means the Pi has power but isn’t booting): this is almost always SD card corruption, the most common hardware issue. Re-image the card with the latest release, or request a fresh one (Swapping the SD Card covers getting at the card on each revision). SD card faults are all-or-nothing — they stop the PiFinder booting rather than causing subtle misbehaviour, so don’t re-image to explain slow solves or the occasional position jump.

  • Keypad lights up, but the screen is blank or garbled: that points to the screen’s connection, not the software. Confirm it through the web interface — if the remote screen looks correct there, the software is fine and the physical screen connection needs attention (a solder reflow on DIY builds).

For re-imaging instructions, see Update Software and the Software Setup page.

The camera view is blank or black

The Focus screen opens on its magnified star tiles, which stay black whenever no stars are detected — so a perfectly healthy camera looks dead there in daylight or under cloud. Don’t judge the camera by that screen.

To see what the camera actually sees, open the Start menu and choose Align (Day). It switches the camera to a short daytime exposure and shows a full live image, which is the quickest way to tell whether the camera is alive at all. Point the PiFinder at something bright and you should get a recognisable picture; even with the lens cap on you should see faint noise rather than pure black.

If Align (Day) shows nothing whatsoever, the Camera Type setting probably doesn’t match the camera in your unit.

  • From the main menu, select Settings, scroll down to Advanced, then select Camera Type and try a different one. The v3 sensors are imx462 and imx296; older v2 cameras are imx477. It won’t hurt to try each.

  • After changing Camera Type you must fully power the PiFinder off and on — a software restart alone won’t apply it.

  • A software update can quietly reset this setting, so re-check it after you update.

It won’t plate solve (“can’t find stars”)

Plate solving is how the PiFinder works out where it’s pointed (see Setting Focus & First Solve). When it won’t solve, focus is the cause far more often than anything else — and stars that look fine at normal zoom are often not tight enough.

Work through these in order:

  • Focus, properly. On the Focus screen, rotate the lens until the four magnified stars are as small as possible and the central HFD reaches its lowest value. The difference between fair and good focus is less than half a turn, so work in steps of an eighth to a quarter of a turn with a pause for vibration to settle, and judge by the HFD rather than the camera icon, which lags a second or so behind each change of the lens. Tight focus matters even more under bright, light-polluted skies, where slightly soft dim stars vanish into the background. If you’re starting from way off, set the lens so about 6 mm of thread is showing — roughly a pencil’s width — which is close to in focus.

  • Lens cap off, and hold still. The PiFinder can only solve a sharp, stationary image.

  • Exposure. The PiFinder defaults to AUTO, setting the exposure itself from each solve — leave it there unless you have a reason not to. To set it by hand, 0.2 s suits most skies, bright urban skies want 0.4 s, and dark skies solve well at 0.1 s. (Software older than 2.2 doesn’t have the AUTO option — another reason to update.)

  • High, thin cloud. An invisible drifting cloudbank will stop solves at an otherwise perfect site. If solves come and go while the scope is dead still, suspect the sky before the hardware.

Note

On older v2 cameras the lens has two rings — a focus ring and an aperture ring. The aperture must be fully open for the PiFinder to see enough stars to solve.

An object has “disappeared” from a list (for example, M45)

Objects are never deleted. If something you expect is missing, it’s being hidden by an active filter — magnitude, altitude, type, observed status, or which catalogs are selected. To bring everything back, open the Filter menu and choose Reset All. See Filters for what each filter does.

The chart or Push-To directions look backwards

Reversed Push-To directions are the classic sign that the PiFinder Type setting doesn’t match your hardware. You push the scope the way the arrows point and the target moves further away instead of closer. A mirrored star chart is the same fault showing itself somewhere else — one setting drives both.

On rev4, suspect this first. The body rotates between the Left, Right and Straight positions without tools, so it’s easy to reposition the unit for a different scope and leave the setting describing where the screen used to face. Set it to match under Settings, as described in Configuration Setup.

Note

The clockwise / counter-clockwise Push-To arrows are also configurable to suit how you picture turning your scope. If only the left/right (azimuth) direction feels reversed, try flipping that preference in Settings rather than changing the PiFinder Type.

“Is this normal?”

A few PiFinder behaviours surprise people into thinking something is broken. These are all expected:

  • The alignment reticle isn’t centred. The Telrad-style reticle on the Align screen shows where your scope points within the camera’s wide 10° view — it isn’t meant to sit in the middle, and a reticle off to one side is normal. See Alignment.

  • The star chart is “zenith up”, not eyepiece-matched. The on-screen chart is a naked-eye view, oriented as you’d see the sky looking up, so it won’t match the flipped or rotated view through your eyepiece. The object image previews, by contrast, are rotated to match the eyepiece.

  • Push-To numbers dim while you move the scope. While moving, the PiFinder estimates position from its motion sensor and dims the numbers to say so; the instant you stop, it takes a fresh photo, the numbers brighten, and the position is exact again. (This is separate from the whole screen dimming in power-save mode.)

  • The charging light is slow to turn green. Near a full charge the current tapers off, so the final stretch from blue to green takes a while. That’s normal, not a fault.

Frequently Asked Questions

Do I still need a finder scope or Telrad?

Not for finding objects — once aligned to your scope, the PiFinder replaces a traditional finder. A zero-power finder (a red dot or Telrad) is handy for the initial alignment, since that step asks you to put a bright star in your eyepiece to select it on the PiFinder’s chart.

Does it work in light-polluted skies?

Yes — very well. Leave the exposure on AUTO and the PiFinder adapts it to the sky; setting it by hand, a longer 0.4 s helps pull stars out under heavy light pollution. Good focus matters most of all here.

How do I update the software?

From the unit, go to Tools → Software Upd while connected to a WiFi network with internet access (Client mode). If the version reads “unknown”, the PiFinder can’t reach the internet to check — that’s a connectivity issue, not a reason to re-image. Full details are in Update Software.

What’s the default password for the web interface?

solveit — all lowercase, one word. The home screen is viewable without it; other pages require it. You can change it under the web interface’s Tools page.

How long does the battery last?

About ten hours, and that’s a floor: it was measured with the camera solving continuously, the screen at full brightness and sleep off, so ordinary observing runs longer. Runtime is highly activity-dependent — sitting on a single object lets the PiFinder drop into a lower-power mode and stretches it, while a fast tour through many objects shortens it. You don’t have to guess, though: the title bar’s battery indicator shows how much longer it will run, and the PiFinder warns at 10% and 5% before performing an orderly shutdown rather than cutting out. For long sessions keep a USB-C power bank handy — you can hot-plug it while the PiFinder is running.

Note

A v3 or v2.5 PiFinder with the PiSugar battery runs for four to five hours, has no battery indicator, and shuts off abruptly when the cell is empty. The v3 manual covers that hardware throughout.

Where are my saved observations and images?

On the PiFinder’s network share, reachable at //pifinder.local/shared (connect as guest, no password). See Shared Data Access.

Can I connect SkySafari?

Yes — the PiFinder talks to SkySafari and other planetarium apps over WiFi. See the SkySafari page for setup.

Can I enter my own coordinates?

Yes. You can type an arbitrary RA/Dec for objects that aren’t in the built-in catalogs — handy for asteroids, comets, or newly discovered objects — and you can also send targets from SkySafari. See Custom Targets for how.

I rotated my PiFinder to fit a different scope — do I need to change anything?

Yes. rev4 is one unit whose body rotates between the Left, Right and Straight positions, and the software has to be told which one you’ve moved it to. Skip that and the Push-To directions come out reversed: you push the scope the way the arrows point and the target moves further away. Set PiFinder Type under Settings to match, as described in Configuration Setup.

Can I use the PiFinder on an EQ mount?

Yes — the PiFinder works with any mount, and plate solving behaves the same whatever the mount type. Switch it to EQ mode in the Settings Menu by setting “Mount Type” to EQ, which presents Push-To distances in RA/Dec instead of Alt/Az. On software 2.5.0 and earlier the accelerometer tracking doesn’t work correctly in EQ mode, so the Push-To numbers are unreliable while you move the scope; once you stop and the camera solves, the correct distances appear. From version 2.6.0 on, EQ mode is fully supported with accelerometer tracking.

Can I control my motorized (GoTo) mount with the PiFinder?

Not yet — this is in active development. It will rely on INDI support for your mount, so even once the software is ready it may not work with every one; check INDI’s supported-mount list at http://drivers.indilib.org/mounts/. There’s no arrival date yet, as it depends on a planned move to a newer OS distribution with a more current version of INDI.

The operating system clock is wrong — does that matter?

No. The PiFinder runs standalone without internet, and the Raspberry Pi has no real-time clock, so it can’t keep accurate time on its own. It saves the time at shutdown and reads it back at startup as a rough estimate, which can be off by days if the unit has been powered down for a while. The software doesn’t trust the system clock — it uses GPS time for everything except log-file timestamps.

To sync the system clock to GPS time, run these commands in a terminal on the PiFinder:

sudo apt update
sudo apt install chrony

Then add the following to /etc/chrony/chrony.conf before the pool directive:

refclock SHM 0 poll 3 refid gps1

This lets chrony use GPS time as a reference. In WiFi client mode chrony will usually prefer internet NTP servers over GPS, so the OS time may still be a second or two off. When running off-grid, the system clock stays inaccurate until you get a GPS lock.

Have another question? Send it to info@PiFinder.io and I’ll do my best to help, and maybe add it here. Better yet, fork the repo and contribute the answer via a pull request.