PiFinder™ User Manual

Note

This documentation is for v3 and v2.5 PiFinders running software 2.2.0 or above. You can see which version you’re running in the upper right of the welcome screen.

If you need docs for a previous version please choose 1.x.x , 2.0.x or 2.1.x

Thanks for your interest in the PiFinder! This guide describes how to use one; if you want to build one, see the Build Guide and the Bill of Materials.

The manual is divided into sections you can reach from the links to the left. Let’s dig into what the PiFinder can do.

How It Works

The PiFinder is a self-contained telescope positioning device. It tells you where your telescope is pointed, lets you pick a target such as a galaxy or other DSO, and directs you on how to move the scope to find it. There are other nice features alongside these core functions, but the PiFinder is designed primarily to get interesting objects into your eyepiece for a look.

To direct you, the PiFinder needs to know where your telescope is pointed. It works this out directly, by photographing the night sky and examining the star patterns to determine which section of sky it’s seeing — incredibly fast (up to 20 times per second!) and very accurately. This only works while the scope is still, so it pairs that camera with an accelerometer that estimates how far the scope has moved since the last solve. The estimate carries some error, but the moment you stop, a fresh photo corrects it.

Knowing where your scope points and where thousands of interesting objects sit, the PiFinder combines the two to show you how to move the scope to bring any of those objects into your eyepiece. Because it observes your actual pointing direction, you can trust you’re on target.

Note

For a general overview of using the PiFinder, read the Quick Start. This manual goes deeper but doesn’t cover the first-time set-up steps in the Quick Start.

Power & Charging

PiFinders ordered with the optional internal battery run for an evening on a single charge, and you can keep one going indefinitely from any USB-C power source. This section covers how the two USB-C ports differ, how charging behaves, how long a charge lasts, and how to look after the battery. For the very first power-on, the Powering the PiFinder section of the Quick Start walks through it step by step.

The two USB-C ports

A battery-equipped PiFinder has two USB-C ports on top, and they do different things:

• The port nearest the back of the case (marked with the arrow above) both powers the PiFinder and charges the battery. Use this one for charging.

• The port nearest the keypad powers the unit only — it does not charge the battery. It is also wired ahead of the power switch, so plugging into it turns the PiFinder on immediately regardless of the switch position.

During a session the keypad-side (power-only) port is the nicer one to run from, because the charging port’s indicator LED is quite bright in the dark. A unit without the battery has only the single power-only port.

The power switch is the small white slide switch on top, above the screen (boxed in the image above). Facing the screen, slide it right for on and left for off. It is a switch, not a button.

Charging

Plug a USB-C cable into the charging port (nearest the back). The indicator LED glows blue while charging and turns green when full. From empty, a full charge takes roughly three hours, though this varies with the power source — a Power Delivery (PD) charger negotiates more power and fills faster, while a basic 5V supply charges more slowly but works fine.

Charge with the power switch off. If the PiFinder runs while plugged in, it can draw about as much current as the charger supplies, so the battery may barely fill. A long charge that leaves the battery still flat almost always means the unit was switched on the whole time.

Note

The last stretch of charging is slow. As the battery approaches full the charging current tapers off, so the change from blue to green can take a while even though the battery is nearly there. This is normal and not a fault.

Battery life

The battery runs the PiFinder for about four to five hours, but real runtime depends heavily on how hard you work it. Sitting at the eyepiece on one object, or stepping away from the scope, lets the PiFinder drop into power-save mode and stretches the time considerably. A fast tour through many objects — camera, motion sensor, and screen all busy — draws more power and shortens it.

There is no battery-level indicator on the screen and no low-battery warning: when the charge is depleted the PiFinder simply shuts off. For a long night, top up beforehand and keep a USB-C power bank handy. You can add external power at any time without restarting (see below).

Note

The PiFinder drops into power-save mode after it has been idle for a while, dimming the screen and slowing the camera to save power. Any button press or movement of the scope wakes it. The idle time can be changed, or turned off entirely, in the Settings Menu.

Running on external power

Any USB-C source rated for at least 2A will run the PiFinder — a wall charger, a USB power bank, or a portable power station’s USB output. As a rough guide, about 1,000mAh of power-bank capacity runs the PiFinder for an hour, so a 10,000mAh bank is good for the better part of a night.

External power can be added mid-session without a restart. A useful trick for stretching a long night: plug a power bank into the power-only port, then switch the battery off. The PiFinder keeps running on the external power while the battery is held in reserve for after the bank is unplugged.

If you hit power dropouts, suspect the cable first — some USB-C cables are unreliable at the ~2A the PiFinder draws, especially on long runs.

Warning

Feed the PiFinder 5V USB-C power only. To run it from a telescope’s 12V supply, you must use a 12V-to-5V step-down (DC-DC) converter with a USB-C output. Never connect 12V directly to the PiFinder — doing so will damage it.

Battery safety & care

The internal battery is a lithium-polymer (LiPo) cell. Treated sensibly it will last for years, but like any lithium battery it deserves a little respect.

Warning

Stop using the battery and disconnect power if it ever becomes swollen, damaged, unusually hot, or develops an odour. A puffed-up or punctured LiPo cell can vent or catch fire. Do not continue to charge or use a cell in this condition — contact us about a replacement.

Warning

Do not puncture, crush, drop, or open the battery, and do not attempt to disassemble the PiSugar power board it sits on. Keep the unit dry; the battery and electronics are not waterproof.

A few habits keep the cell healthy:

• Charge from the built-in port only. The PiSugar power board manages charging for you; just supply 5V USB-C as described above. There is no need for an external LiPo charger, and you should not connect one.

• Charge where you can keep an eye on it, and not on or near anything flammable. Avoid charging or leaving the unit in extreme heat — a closed car on a sunny day is the classic way to cook a battery.

• Mind the temperature. The PiFinder has been used from about -15°C (5°F) to 40°C (100°F). Capacity drops in the cold, though the computer’s own heat keeps the cell warm enough to work in most conditions. Avoid charging a battery that is below freezing.

• For long-term storage, leave the cell partly charged rather than full or empty and keep it somewhere cool and dry. Top it up every few months so it does not discharge completely.

• Dispose of it responsibly. A worn-out lithium battery should go to a battery-recycling drop-off, not the household rubbish.

Note

If you ever need to replace the battery, the only compatible part is the PiSugar S Plus 5000mAh. Other PiSugar models share the I2C bus with the PiFinder’s motion sensor and will cause problems, so make sure you fit the S Plus.

Adjusting Brightness

You can adjust the brightness of the screen and keypad at any time: hold the SQUARE button and press + for brighter or - for dimmer. At a dark-sky site, turn the brightness right down to preserve your dark-adapted vision.

Note

The PiFinder dims the screen and slows exposures, solving, and other processes after it’s been idle for a while. This saves battery power and prevents glare at the eyepiece in especially dark environments. The default is 30 seconds; you can change it, or turn it off completely, in the Settings Menu

Pressing any button, or moving the PiFinder, will wake it from power-save mode.

The Menu System

All of the PiFinder’s functions are reached through its menu system:

Each menu is a list of items representing a submenu, a screen, or a set of options. Scroll through a menu and make selections with these keys:

• The UP and DOWN arrows scroll the current menu

• The RIGHT arrow activates the current option, selecting it or moving to another menu

• The LEFT arrow takes you back to the previous menu or screen

• Holding LEFT for more than a second always returns to the TOP of the menus

The status bar at the top of the screen shows the name of the menu you’re viewing.

Screens

Some menu items, like Camera, lead to a specific screen — a camera preview, a star chart, or details about a catalog object. Each screen is covered in more detail below.

Options

Some menus present a list of options where you choose one or more items to control how the PiFinder operates. For instance, the Filter menu items take you to a sub-menu of ways to filter your object lists:

Selecting Type presents the DSO types you can choose to control which objects appear in your object lists.

Lists that offer selections show a check-mark next to the one or many options selected. Pressing the RIGHT arrow with an option highlighted selects or de-selects it.

For menus that allow only a single selection, such as Altitude, choosing one item de-selects any others. Multi-Select menus offer options to select or de-select all items at once.

When you’re done, press the LEFT arrow to return to your last menu or screen.

With this simple set of scroll-and-select tools you can reach all the PiFinder’s powerful features.

Quick Menu

You can reach everything through the menu system, but a secondary quick-menu brings some functions into easier reach.

Hold the SQUARE key to open the Quick Menu

This menu presents up to four options, one per arrow button; press the arrow to select its item. The menu changes with the screen you’re on, but often has HELP at the UP option. The Focus screen above offers HELP and Exposure.

Some Quick Menus have a second layer. The Object List’s Quick Menu, for example, offers Sort and Filter; pressing LEFT for Sort opens a ring of sort orders, with subtle shading marking the current one.

Pick a sort order to apply it. Exit the Quick Menu at any time by pressing SQUARE again.

Help System

Many screens offer help with specific button functions and other details about how things work or what a page is for.

When available, HELP is the UP option in the Quick Menu

Pressing the UP arrow selects help and displays one or more pages. A prompt at the top or bottom of the screen shows when more pages are available; press UP or DOWN to scroll through them.

Settings Menu

All user-configurable items live in the Settings Menu, near the bottom of the main PiFinder menu.

The top items collect several options under User Preferences and Chart Screen. An ellipsis (…) indicates more options below.

Below the general UI options are settings to change which WiFi mode your PiFinder is in and its physical configuration.

Observing with PiFinder

Out under the stars, you’ll be doing four basic things in various combinations:

• Curating a list of objects you’re interested in

• Viewing details about those objects

• Pushing the scope to bring them into your eyepiece

• Logging your observations

Everyone observes their own way, so the PiFinder offers different ways to use (or skip!) these features for a great night out.

Object List

The Object List is one of the PiFinder’s main features. It presents a collection of objects you’ve selected using catalogs, filters, observing lists, and text search.

To pick a starting point, choose Objects from the main PiFinder menu, then choose one of four options:

• All Filtered: All objects across all catalogs that meet your filter criteria. This could be thousands of objects and is most useful with strict filters, such as globulars above 30 degrees altitude and brighter than magnitude 10.

• By Catalog: All objects from a specific catalog that meet your filter criteria. Great for observing projects and finding the nearest objects in a particular catalog.

• Recent: Starts empty and builds a history of the objects you’ve checked out during the current session.

• Name Search: Using the number keypad and T9-style text entry, search for objects by name. The Snowball planetary? Cat’s Eye? This is the way to find them.

However you build the list, it always displays the same information and offers the same sorting and selection.

A symbol along the left shows each object’s type. Next to it is the designation — usually the catalog abbreviation and index number — then the distance from your current telescope position. Each entry’s brightness hints at its magnitude.

Pressing the SQUARE key cycles through additional information for the objects on the list.

You can see a scrolling list of common names for each object.

And the magnitude and size of each object, with a check mark to indicate whether you’ve observed and logged it before.

Holding the SQUARE key brings up the Quick Menu to sort and filter this list.

Pressing LEFT selects SORT

By default, lists use STANDARD order — usually the order they appear in catalogs. Press the indicated arrow to choose another order such as NEAREST, which puts the object closest to your current telescope position at the top.

If you start typing a number, the Object List jumps to the next object with that index number. Use the UP/DOWN arrows to step to the next or previous match, and the SQUARE key to exit jump mode and select an object.

Pressing the RIGHT key brings you to details for the selected object.

Object Details

Pressing the RIGHT key from the Object List brings up the Object Details screen for the highlighted object. This screen shows large Push-To instructions, object images, and catalog details.

Pressing SQUARE cycles through the object’s information and UP/DOWN moves to the next or previous object in the list. LEFT returns to the full list, and RIGHT brings up the Logging interface for the current object.

The Push-To info shows which way, and how far, to move your telescope to put the object in your eyepiece. As you move the scope the numbers dim, indicating the PiFinder is using the accelerometer to estimate where the telescope is pointing. When you stop, or move slowly enough, the camera plate solves to provide an absolute position and the numbers brighten again.

When the numbers are near 0.00 the object should be in your eyepiece. The numbers are the distance to the object in degrees, so with an eyepiece offering a 0.5 degree true field of view, getting them below 0.25 (half the true field) should put the object in view.

Closer to zero means more centered. For a very dim object, knowing it’s dead center and consulting the object image can make all the difference.

The PiFinder can display images of every object in its catalog. See the section on object images below for more.

Depending on the catalog, the PiFinder may have detailed notes along with Type, constellation, magnitude, and size. Use the +/- keys to scroll the notes field. At the bottom of the notes is a count of how many times you’ve logged this object.

Filters

Every object list aside from Name Search and Recent shows only objects that meet the filter criteria you’ve set. View and adjust your filters from the Filter menu, available on the main PiFinder menu.

You can also jump to the filter options from the Quick Menu on the Object List screen.

The Filter menu offers several ways to limit which objects appear, plus a Reset All option to clear every filter.

With no filters set, every available object appears — the All Filtered list will show over 18,000 objects!

Some filter types take a single value, like Altitude, and some allow multiple selections, like Object type. Here’s a brief explanation of each:

• Catalogs: Limit which catalogs are included in the All Filtered list. This is distinct from the catalog-specific object lists, which are a shortcut to one catalog. Using the Catalogs filter, the All Filtered list can show globular clusters across multiple catalogs at once.

• Type: Limit by object type. You can select multiple types to include.

• Altitude: The current apparent altitude of an object from your observing location.

• Magnitude: Limit to objects at least as bright as the selected magnitude.

• Observed: Include only objects you’ve logged, never logged, or any logged state.

Catalogs Filter

The PiFinder has many catalogs, so this menu groups them by category.

Common catalogs appear at the top level for quick reference; less common ones sit in sub-categories marked with an ellipsis (…).

Here’s the DSO… category as an example:

Selected catalogs show a check box, and you may see the same catalog, like Messier, in multiple spots. Selecting or de-selecting anywhere changes its state everywhere.

Name Search

A powerful way to search the PiFinder’s large object database is by name, letting you find objects by their common description, like the Cat’s Eye nebula. To reach the Name Search screen, select it from the Objects menu:

It uses T9-style text input, like the cellphones from the dawn of text messaging. The on-screen keypad shows the letters available by pressing each number key several times in a row.

Each number key generates its number, then the three or four letters shown, in turn. Pause long enough between presses, or press a different key, and the cursor moves to the next position.

As you type, the PiFinder shows how many objects match your search term, to the far right of your text.

The count drops as you add more text.

Once you’ve narrowed the list enough, press the SQUARE key to see the full list of matches.

Object Images

If you used the prebuilt PiFinder image or have downloaded the set of catalog images, you can see what the selected object looks like via sky-survey images. These display in the background of the Object Details screen, and you can view them in full detail by pressing the SQUARE key to cycle through the pages of information about each object.

The images are rotated and oriented as they appear through the eyepiece at your position and time, to help you identify the faintest targets.

Zoom in and out with the +/- keys; the FOV is displayed at the bottom of the image so you can match it to your eyepiece.

As an example, here are the images available for M57

These images are oriented to match the view through your eyepiece for the telescope you’re using, pointing at a specific area of sky from your current location. By default they’re oriented for a Newtonian reflector; if you use a refractor or an SCT with a star diagonal, set the orientation options for your telescope as described in Equipment. Use the + and - keys to switch between the fields of view of the eyepieces you configured via the Web Interface

The bottom left of the screen shows the source of the current image, and the left side shows the current FOV information.

Logging Observations

Pressing the RIGHT arrow while viewing any object’s details brings up the logging interface, where you can add context about your observation and save it to your log.

Use the UP/DOWN arrows to select one of the four context items to change:

• Observability: How easy is it to spot and recognize this object

• Appeal: Overall rating — would you refer a friend?

Set these first two by choosing a number from 1 to 5, or pressing the RIGHT arrow to cycle through the stars.

• Conditions…

  • Transparency: A relative measure of contrast.

  • Seeing: The stillness of the atmosphere.

• Eyepiece: Note which of your eyepieces you’re using.

When you’re done — or if you just want to note that you observed an object without context — use the UP/DOWN arrows to select SAVE LOG and record your observation.

Observing Projects

If you’re like me, you may enjoy observing projects, such as working through all the Messier or Herschel objects. The PiFinder makes these long-term efforts easy: log each object, and it will then show you only the objects you have left that are visible during any session.

Combining a filter on observation status with an object list sorted by NEAREST lets you work through a collection easily.

Tools

Near the bottom of the main PiFinder menu, the Tools option leads to a set of screens that aren’t observing-related but provide useful information or let you perform actions.

• Status: General info about PiFinder operation.

• Equipment: Choose your active telescope and eyepiece, and see the resulting magnification and field of view.

• Console: Shows messages from various PiFinder subsystems

• Software Upd: Updates the software of your PiFinder.

• Test Mode: Puts the PiFinder into a demo/debug mode that loads and solves an image from disk. It prevents proper operation at night but lets you explore PiFinder features during the day.

• Shutdown: Shuts down the PiFinder

Status Screen

The Status Screen is the central place to check the PiFinder’s current state and operation.

Some of the key information shown:

• The current solver state, as LAST SLV on the top line. It shows the seconds since the last plate solve, the solve type (i for IMU or C for camera), and, for a camera solve, the number of stars matched.

• WiFi information a bit further down, including the current WiFi mode, network name, and IP address.

Shutdown

Shutting down isn’t strictly required before power-off, but the PiFinder is a computer and there’s a chance of file corruption if you skip it. Some MicroSD cards are more sensitive than others.

The Tools menu offers a Shutdown option, and there’s a quick way to reach it too.

To shut down the PiFinder quickly:

• Hold the LEFT arrow button for more than a second to jump to the main menu

• Hold the SQUARE button to access the Radial menu

• Press DOWN to select the SHUTDOWN option

• Use the RIGHT arrow to confirm, or the LEFT arrow to go back

After you confirm, the screen and keypad turn off within a few seconds; it’s then safe to turn off the unit with the power switch or by unplugging the battery.

WiFi

Access Point and Client Mode

The PiFinder can connect to an existing network in Client mode, or serve as a wireless access point for other devices in Access Point (AP) mode. Use the Web Interface or the Status Screen to switch between the two modes and see which is active.

In Access Point mode the PiFinder creates a network called PiFinderAP with no password, for easy connection of phones, tablets, and other devices in the field.

To use Client mode, add the WiFi network you’d like the PiFinder to connect to using the Web Interface, as described in Connecting to a new WiFi network

PiFinder address

In most cases you can reach the PiFinder at pifinder.local. On older computers, or those without zeroconf networking, use the IP address shown on the Global Options screen. You can connect via:

• A web browser, for the Web Interface — remote control, WiFi setup, and configuration changes

• SSH, for shell access (advanced users)

• SMB (Samba), to access saved images, logs, and observing lists

• LX200 protocol, to update a planetarium app such as SkySafari with the telescope’s position

Web Interface

The PiFinder’s web interface lets you:

• See the current PiFinder status

• Remote control the PiFinder via a virtual screen and keypad

• Change network settings and connect to new WiFi networks

• Add and edit your telescopes and eyepieces (see Equipment)

• Back up and restore your observing logs, settings, and other data

• View and download your logged observations

To reach the web interface for the first time, make sure the PiFinder is in Access Point mode (see Settings Menu) — the default for new PiFinders, to ease first-time setup. From a phone, tablet, or computer, connect to the PiFinder’s open wireless network, PiFinderAP (no password), then open your browser and visit: http://pifinder.local

Note

If you’re connected to the PiFinderAP network and can’t load the web interface at http://pifinder.local, try http://10.10.10.1 — some systems don’t support the network features needed to resolve local computer names.

The home screen shows general PiFinder status and a live view of the screen. Depending on your screen size you’ll see either a navigation bar along the top or a ‘hamburger’ menu in the upper-left holding the same options on smaller screens.

The home screen needs no password, but most other functions do. The web interface password is the same as the pifinder user’s; changing one changes the other. The default for new images and PiFinders is solveit, and you can change it from the Tools option in the web interface.

Connecting to a new WiFi network

By default the PiFinder generates its own WiFi network, PiFinderAP, that you connect to in order to configure additional networks. To have the PiFinder connect to an existing WiFi network with Internet access, follow these steps:

1. Make sure the PiFinder is in Access Point mode

2. Connect your phone, tablet, or computer to the PiFinder’s wifi network called PiFinderAP

3. Visit http://pifinder.local using your web browser

4. Click the ‘Network’ link in the top bar, or on a smaller screen click the three stacked horizontal lines in the upper-right corner and choose ‘Network’.

   

5. When prompted, enter the password for your PiFinder. The default is solveit.

6. Scroll down to the ‘Wifi Networks’ section and click the + button to add a network

   

7. Enter the name (SSID) and password of your network. If your network has no password, leave the Password field blank.

8. Click the ‘SAVE’ button to save the new network

9. The network you added should now appear in the ‘Wifi Networks’ section

10. Scroll up and change the Wifi mode from ‘Access Point’ to ‘Client’ so the PiFinder connects to your network on its next restart

11. Click the ‘UPDATE AND RESTART’ button

To add more WiFi networks, navigate to the Network Setup page of the Web Interface, click the + button near the WiFi networks list, and repeat the steps above.

SkySafari

The PiFinder can provide real-time pointing information to a device running SkySafari via the LX200 protocol. See the SkySafari document for full details; here’s the connection info:

• Use ‘Other’ telescope type

• Mount Type: Alt-Az, GoTo — even if your scope is Push-To. This lets SkySafari send targets to the PiFinder

• Scope Type: Meade LX200 classic

• IP Address: pifinder.local or the IP address shown on the Status screen

• Port: 4030

Shared Data Access

The PiFinder creates several data files you may want. They’re available via an SMB (samba) network share, //pifinder.local/shared. Access depends on your OS, but the PiFinder should appear in a network browser. No password is required — connect as guest with no password.

Once connected, you’ll see:

• captures/: Images saved when logging objects, named with the observation ID from the database.

• obslists/: Observing lists saved during a session or kept for future sessions.

• screenshots/: Screenshots taken while using the PiFinder (hold ENT and press 0) are stored here.

• solver_debug_dumps/: If enabled, solver performance information is stored here as a collection of images and json files.

• observations.db: The SQLite database holding all logged observations.

Update Software

The PiFinder can download and install software updates directly from its screen and keypad. To start, choose Software Upd from the Tools

Updates happen right on the device — there is no need to send your PiFinder anywhere. New units often ship a version or two behind the latest release, so running an update is a normal part of your first night out.

The PiFinder needs internet access, so put it in Client Mode connected to a WiFi network. See Connecting to a new WiFi network for details.

The PiFinder confirms it can reach the internet, then compares the current release version to the one installed.

Note

If the release version shows as unknown, the PiFinder cannot reach the internet to check — it is either in Access Point mode or its WiFi is not configured. Put it in Client mode on a network with internet access (see Connecting to a new WiFi network); re-imaging the SD card is not the fix for this. If WiFi is configured but the check still fails, move closer to the router or re-enter the network details.

If a new version is available, use the presented option to start the update. This may take several minutes, and the PiFinder restarts when it’s done.

You can also download a pre-built image of any software release and write it to the PiFinder’s SD card. See our release page for information about each release and a download link.

Instructions for writing release images to an SD card are on the software setup page.

FAQ

Frequently asked questions now live on the Troubleshooting & FAQ page.