Comparison

PF vs Polar Scope Align Pro

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

PF

Read full description

The PF-L Assist is a free app for smartphones and tablets in order to support polar axis setting which is basic to your equatorial mount. The PF-L Assist app makes it possible to set the field of view of your polar alignment scope PF-L II at the specific date and time of your observation. (It is usable in both the northern and southern hemisphere.) [Functions] Orientation of the scale and position of starts are indicated in real time. The orientation of the scale and the position of the stars are computed automatically in accordance with the date, time and site of your observing session. An image of the field of view seen though the polar alignment scope at the time of observing is indicated on the screen of your smartphone or tablet. It is available for both the northern and southern hemisphere (Automatic or manual operation are available). Adjacent stars of no relevance to the polar alignment are not indicated in the imaginary field of view so that you can instantly recognize the position of the stars you want. After you confirm the position of the stars with the app, it is easier to polar align your PF-L scope. [How to use] Usage in the northern hemisphere is shown as an example. (1) Start up the app. (2) While looking through the polar alignment scope, turn the scope’s scale so that it comes to the same orientation as the scale indicated on the screen of the app. (3) The direction of the scope’s scales is parallel to the scale on the app. (4) Bring Polaris to the designated position on the scale in the field of view of the polar alignment scope by adjusting the equatorial mount in azimuth and/or altitude directions and finish the polar alignment setting. For beginners and those who are unfamiliar with the polar alignment scope, it may take time to set up the equatorial mount. The polar alignment requires a process that matches the reticle with the actual rows of stars by turning the polar alignment scope. The app enables you to simplify this process and quickly advance to the polar alignment by Polaris. Vixen’s polar alignment scopes are designed to align the equatorial mount using Polaris and two reference stars named Delta UMi and 51 Cep to increase accuracy of the polar alignment (in the northern hemisphere). If the above two reference stars are added to your polar alignment, you will increase the setting accuracy and tracking precision. These two reference stars are less bright than Polaris and may be difficult to find. Using the app you will find it easier to locate the two reference stars. Assisting the polar alignment, the PF-L Assist app is a highly convenient app for those who use an equatorial mount first time. [Enlargement] The imaginary field of view of the polar alignment scope on the app is enlarged and you can easily check the position of the stars. [Night vision] Switching ON the night vision mode in the setting screen will turn the screen of the app to illuminate in red, which allows you to keep your eye's sensitivity in night observing. [Support page] Help, support page is provided in the setup menu. The support page links you to the Vixen web site.

About

Polar Scope Align Pro

This app assists astronomers with precise polar alignment for telescopes, offering tools for various reticles and low-latitude accuracy. It also includes a comprehensive suite of astro tools, from object databases to calculators and weather reports.

Highlights
  • Accurate polar alignment calculation
  • Support for numerous polar scope reticles
  • Daytime/no polarscope alignment tool
  • Deep Space Object database
  • Astrophotography calculators
  • World astro-weather report
Features
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Polar Scope Align Pro is a complete toolkit for amateur astronomers: accurate polar alignment, deep-sky observing, astro weather, push-to/manual GoTo, iOptron mount WiFi control, widgets and more. All features and updates are free forever. Optional in-app purchases are just tips to support development. POLAR ALIGNMENT • Calculates Polaris or σ Octantis position for 30+ reticle types: iOptron, Astro-Physics, Takahashi, Skywatcher, Vixen, Celestron, Orion, Astrotrac and others* • Atmospheric refraction correction for accuracy at any latitude • Works with or without a polar scope ALIGNMENT WITHOUT A POLAR SCOPE • Daytime / No Polar Scope Alignment: works day and night with just your phone's gyro • Camera Azimuth Calibration: use sun/moon/stars to calibrate gyro and align accurately without a compass, immune to magnetic interference • Laser / Hop Align: nighttime alignment for maximum accuracy with a laser or a scope with no view of Polaris • Live sky map guides you to the celestial pole in real time • Sun Finder helps you point your filtered telescope/telephoto to the Sun PUSH TO (MANUAL GOTO) • Attach your phone to any scope and convert it to manual/push GoTo • Select from a large database and use direct push or more accurate hop-to mode DEEP SKY OBJECT DATABASE • 22,000+ objects with altitude graphs, rise/set times and more info • Save and manage curated observing lists • Filter, search, sort and push to any target XASTERIA ASTRO WEATHER • Hourly astronomy forecasts from 7Timer, OpenWeather, MET Norway and Apple Weather, plus a configurable Multi-source forecast • Animated satellite Cloud Map with recent EUMETSAT and NASA infrared imagery • Aurora forecasts • ISS and bright satellite passes with an All Sky night chart, individual sky charts, live map tracking, and Tiangong and Hubble views • Solar eclipse tool with past and future eclipses, live mode with audio cues • Experimental eclipse camera for automated photoshoots of partial phase, diamond ring, Baily's beads, totality bracketing • Interactive light pollution map using World Atlas and recent VIIRS data CALCULATORS & TOOLS • 30+ calculators for observing and astrophotography • Moon phase calendar with altitude graphs • Solar eclipse calculator and simulator • Bubble level & Compass IOPTRON WIFI MOUNT CONTROL • Connect to WiFi-enabled iOptron mounts (HAE, HAZ, HEM, CEM, GEM and more) • Automatic date/time/location setup • Switch between Equatorial and Alt-Az on mounts that support both • Move & Sync: directional control with a live sky map • Point GoTo: aim your phone at a patch of sky and send the mount there • Current Point Query: find out what the mount is pointing at • GoTo any object from the DSO Database NIGHT-FRIENDLY • Red, green or white night mode with dimmer WIDGETS • Configurable Tonight and Multi astronomy weather forecasts • Upcoming bright satellite passes • Aurora probability, activity forecast and NOAA aurora map * Full list of supported reticles: Astro-Physics RAPAS & PASILL, iOptron, the latest Orion / Skywatcher, the Classic Skywatcher / Orion / Celestron / Meade / EXOS2 / Bresser / MSM, various versions of Takahashi EM-10/11/200/400/500, NJP, PM-1, P2-Z, the Telrad, Rigel QuikFinder, a couple for Astrotrac / Losmandy / Kenko / Avalon, the Vixen PF-L/Atlux/SX/SXD/SXP/AXD/GP/GP-DX/Polarie Polar Axis Scopes, a Konus and several Polar Finders: Tuthill, Explore Scientific 8x50, Meade 9x60, Vixen Polaris, Celestron 7x50, Carton Optical. PoleMaster help view for South Hemisphere users.

Screenshots

PF2 screens
Polar Scope Align Pro4 screens

Verdict

The call

The clearest difference is price: PF at Free against Polar Scope Align Pro's $4.99. PF also leads on in-app purchases (none vs 3). Polar Scope Align Pro's advantage is update cadence (every 2 months vs every 11 months). On ads, device support and iOS requirement there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

PF is free to download; Polar Scope Align Pro costs $4.99 up front. Polar Scope Align Pro sells 3 one-off in-app purchases. PF asks for nothing beyond the download.

UpkeepUpdate frequency

PF ships an update every 11 months, Polar Scope Align Pro every 2 months. Both last shipped on October 29, 2026.

Scorecard3 real differences · 7 level
PF versus Polar Scope Align Pro: the parameters behind the verdict, then further details
ParameterPFPolar Scope Align Pro
PriceFree — better$4.99
Rating—4.9 (310 ratings) — better
Positive reviews—96.7% of reviews
Number of ratings—310 — better
Update frequencyEvery 11 monthsEvery 2 months — better
AdsNoNo
In-app purchasesNo — betterYes
Monetization—Free with in-app purchases
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS12.0 — better13.0
Further details — not scored
Size8 MB33 MB
Age rating4+4+
DeveloperVixen Co.,Ltd.Dimitrios Kechagias

Bugs and requests

PF

Not enough reviews yet to summarise bugs or requests.

Polar Scope Align Pro

Reported bugs

2 issues
  • Weather Updates Not Working
  • Compass Deflected by Mount

Requested features

2 requests
  • Add Observation Recording Feature
  • Add Push To Option for DSO Objects

In-app purchases

None

PF

No in-app purchases

3 purchases

Polar Scope Align Pro

One-time3
  • Tip 1x$0.99
  • Tip 4x$3.99
  • Tip 10x$9.99

Questions

Is PF free?
PF is free to download, with no in-app purchases.
Is Polar Scope Align Pro free?
Polar Scope Align Pro costs $4.99, and also offers in-app purchases.
Do PF or Polar Scope Align Pro have ads?
Neither PF nor Polar Scope Align Pro shows ads.
Which is updated more often, PF or Polar Scope Align Pro?
PF ships an update every 11 months, and Polar Scope Align Pro every 2 months. Most recently, PF was updated on October 29, 2026 and Polar Scope Align Pro on October 29, 2026.

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