In my first blog post about the Seestar S30 Pro, I documented its “first light” under a clear night sky. However, one important accessory was left untouched in the carrying case during that initial night session: the solar filter.

On the afternoon of July 14, 2026, the weather finally turned sunny, giving me the perfect opportunity to test the smart telescope during the day and catch a glimpse of our home star.

Start of heading level 2: ## Important Safety Note End of heading.

Observing the sun carries extreme risks. Pointing a telescope at the sun without proper protection will instantly destroy the camera sensor (and cause blindness if viewed directly with the human eye). The Seestar S30 Pro features a highly sensitive dual-camera system (Sony IMX585 & IMX586). Without a filter, the optics would literally melt the sensor.

Start of heading level 2: ## The Solar Filter: Simple and Magnetic End of heading.

ZWO includes a compact solar filter with the Seestar S30 Pro. The filter itself consists of a safe solar attenuation film mounted in a round plastic frame.

I particularly like the mechanical design: the frame is not screwed on or attached with a friction ring; instead, it features a magnetic mount. You simply hold the filter in front of the Seestar’s lens, and it snaps precisely and securely into place. This has two key benefits:

1. The filter can be attached and removed safely in a fraction of a second.
2. There is no mechanical stress or friction on the body that could misalign or scratch the telescope.

Start of heading level 2: ## Setup and Alignment During the Day End of heading.

Daytime setup is just as simple as the nighttime process. This time, however, I used the small tripod included in the package and set up the telescope relatively close to the ground. After powering it on and connecting to the Seestar app, you select the Solar Mode.

Before the telescope makes a single move, the app displays a prominent safety warning prompting the user to attach the solar filter. The process only continues after confirmation.

Since the telescope cannot use stars for orientation during the day, it relies on its internal compass and the smartphone’s GPS data to find the sun.

• Automatic Go-To via Compass: After starting the Solar Mode, the Seestar attempts to automatically point at the sun using its internal compass. While this sounds great in theory, in practice, the alignment on my first attempt was way off. The telescope’s compass seems prone to interference (possibly due to nearby metal objects or because it wasn’t calibrated yet).
• Restarting for Re-initialization: Instead of painstakingly searching for the sun manually using the virtual joystick in the app, I simply restarted the telescope. After the reboot and reconnecting, the compass apparently recovered: on the second attempt in Solar Mode, the Seestar pointed directly and precisely at the sun.
• Locking On & Tracking: Once the sun entered the sensor’s field of view, the software successfully detected the bright solar disk, centered it automatically, and began tracking. From that point on, the tracking was rock-solid—the sun remained locked in the center of the screen.

Start of heading level 2: ## The Results: Target Sunspots End of heading.

During my test in the late afternoon of July 14, I captured two nice shots that showcase the capabilities of the Seestar S30 Pro.

Start of heading level 3: ### Close-up with Digital Zoom (5:34 PM) End of heading.

For the first image, I used the digital zoom in the app to crop in on a specific detail near the edge of the sun.

This shot shows a highly prominent, active sunspot group near the right edge (southwestern solar horizon). Cross-referencing current space weather data, this is the active region AR4485. At the time of capture, it was rotating out of view over the western horizon of the sun. The dark core (the umbra) and the slightly lighter, fibrous border (the penumbra) are clearly visible. To the left (closer to the center), another slightly smaller structure can be seen.

Start of heading level 3: ### The Full Solar Disk (5:40 PM) End of heading.

A few minutes later, I took a shot without digital zoom to capture the entire sun.

Without digital zoom, the circular solar disk stands out sharply against the deep black background of space. On this overview shot, the larger spots (including region AR4482 near the upper section) remain clearly visible as dark dots on the otherwise uniformly bright photosphere.

Start of heading level 2: ## Scientific Breakdown: What Are Sunspots? End of heading.

The dark spots on the sun are not holes; they are a fascinating result of magnetism and thermodynamics:

• Strong Magnetic Fields: Inside the sun, hot plasma rises to the surface via convection, cools, and sinks back down. In some areas, local magnetic fields are so strong that they block this vertical transport of plasma.
• Temperature Difference: Because no fresh, hot plasma can flow into these blocked areas, they cool down. While the normal solar surface (photosphere) is about 5,500 °C, the temperature at the center of a sunspot (umbra) is “only” around 3,800 °C.
• Brightness Contrast: Since cooler gases emit less light, these regions look black in direct contrast to the extremely bright surroundings. If you were to place a single sunspot by itself in the night sky, it would still shine brighter than the full moon!
• Activity Cycle: The number of sunspots fluctuates on an 11-year cycle. Since we are in the middle of the maximum of Solar Cycle 25 in 2026, the sun is currently highly active, presenting spectacular spot groups for observation almost daily.

Start of heading level 3: ### Impact on Amateur Radio End of heading.

As a licensed radio amateur (callsign DO3EET), I track solar activity for more than just visual appeal. Sunspots have a direct and major impact on our hobby:

• Improved Propagation: The intense ultraviolet radiation associated with sunspots ionizes the F-layer of Earth’s atmosphere (ionosphere). A more densely ionized ionosphere acts as a better mirror, reflecting high-frequency (HF) signals back to Earth.
• DX on Higher Bands: During the current solar maximum, the higher bands (such as 10m, 12m, and 15m) regularly open up for worldwide contacts (DX) even with low transmit power.
• The Downside – Radio Blackouts: Highly active sunspot groups can produce solar flares. When these hit Earth, they can cause Sudden Ionospheric Disturbances (SID) and complete radio blackouts on the sunlit side of the planet.

Start of heading level 2: ## Conclusion End of heading.

Testing the solar filter was a fantastic experience. The combination of the safe, simple magnetic mount and the app’s intelligent solar search makes observing the sun with the ZWO Seestar S30 Pro incredibly easy and completely safe. Whether for a quick look during the day or preparing for astronomical highlights like eclipses, the system works flawlessly.

Note: On August 12, 2026, a partial solar eclipse will occur, which will be visible with high coverage in Germany. With the Seestar S30 Pro and the solar filter, you are perfectly prepared for this event!

Have you had any experience with solar observation, or have you managed to capture the sunspots of the past few weeks with your setup? Let me know in the comments below!