Raspberry Pi Automated Sunspot & Solar Eclipse Camera

This Instructable describes using a Raspberry Pi computer and Raspberry Pi Camera Module to make a Solar Camera for the 2024 Solar Eclipse. The traditional options for watching a solar eclipse include special glasses for naked eye protection, paper projection screens, telescopes with solar filters, DSLR cameras with telephoto a lens, and more recently adapting an iPhone camera to capture eclipse video. But because of the recent availability of Raspberry Pi Camera Modules with high quality CCD camera chips and my interest in exploring more Raspberry Pi applications, I decided to go this route.

After the Eclipse event, I realized the same Raspberry Pi Solar Camera was perfect for capturing other solar events, like sunspots. As you will read below, this synergy is particularly true because observing an eclipse, and observing sunspots, both require taking sequences of images, which this camera does. Unlike solar eclipses, sunspots have an almost daily appearances and can affect out daily lives in interesting ways. As a result, I extended this Instructable to describe both capturing the total solar eclipse in April, and how it can be used later to capture and study sunspot images.

Constructing a Raspberry Pi Solar Camera

This Instructable describes making a Raspberry Pi Solar Camera that will take sequences of images. It includes information about selecting the best solar filter, the optimal lens focal length, details about a "drift method" to capture a sequence of images before, during, and after totality, almost hands off, and avoid frantic readjustment. In the case of the Total Solar Eclipse, this camera automates the collection of a sequence of images as the moon passes over the sun. In the case of sunspots, this camera will produce sequences of images of the sun that can be easily processed to produce enhanced images of sunspots on the sun. With only small modifications the same Raspberry Pi Solar Camera can be used to capture sunspot images by using a different lens and software processing.

Expanding Your View of Astronomy

When most people think about astronomy as a hobby, they only think about the traditional challenge of capturing dim observations of the planets and stars, usually on cold nights. It is easy to overlook that the brightest and most accessible object in the heavens is up literally all day, very bright on warm, clear days. Unlike some Instructables that require complex knowledge and skills about computers and building electronic hardware, making this Raspberry Pi Solar Camera only requires connecting several working components into a camera assembly. Unlike traditional astronomy that is most satisfying with expensive telescopes or lenses, the lenses that are used in this Solar Camera can be very inexpensive. As a result, this Instructable is a perfect project for both young students, as well as unskilled adults, to start them on a new hobby in solar astronomy.

I have including links at the end to articles that I found particularly helpful with more details about the drift method, eclipse imaging and sunspot imaging.

Basic System Components:

Raspberry Pi 4 computer: https://amzn.to/3TApzIU from RaspberryPi.com

Raspberry Pi Camera Module with C Lens Mount: https://amzn.to/3TwlXHK

ArduCam 50mm Telephoto Lens for Raspberry Pi Camera with C-Mount https://amzn.to/4amKYwl

Raspberry Pi 4 inch LCD Display, 800x480 HDMI: https://amzn.to/4a3AykV

Baader AstroSolar Visual Solar Filter Film (ND 5) - 140x155mm: https://amzn.to/4a7Hg9y

Fluid Pan Tilt Head and Quick Release Plate for Tripod: https://amzn.to/4axiDmJ

Tripod (many options, but get as solid one as possible to avoid giggling when changing filters)

SunFounder PiPower Raspberry Pi UPS Power Supply (Battery Included): https://amzn.to/4cre7YB

Optional Suggestions:

If this is your first RPi project I suggest you get one of the starter packages: https://amzn.to/3x8Gbjg

Wireless BlueTooth Keyboard : https://amzn.to/3TylQeZ

Wireless BlueTooth Mouse: https://amzn.to/3TRILSH

7 Inch Small Raspberry Pi Monitor: https://amzn.to/3PAlwLc

4.5" steel mounting bracket https://amzn.to/3vnmtjv

3" Steel Inside Corner Brace https://amzn.to/43LO3DB

Optional Telephoto Lens for Larger Solar Images

C-Mount Zoom Lens: I used a 70-300mm zoom lens, available used on eBay

This example used: Tamron AF 70 - 300 mm f4 - 5.6 LD Tele - Macro 1:3.9 Camera Zoom Lens

Imaging a Total Solar Eclipse Sequence

My goal for the solar eclipse was to capture the classic sequence of images of the Sun before, during, and after totality, as shown in the image above. While there have been numerous descriptions of how to set up a telescope with a solar filter and camera to take images of the Sun, using that apparatus to capture the desired sequence would require continually repositioning the camera manually for several minutes. After reading several articles by veteran eclipse photographers, their number-one advice was to make sure having your own visual experience was the priority and not to get distracted and miss it maintaining some piece of gear you have set up to record the experience. With that advice in mind, the primary goal of this Instructable is to describe how to make an automated solar telescope using a Raspberry Pi computer and a Raspberry Pi Camera to capture the full sequence of eclipse images hands-off. One design solution accomplishes this by building a camera mount that uses complicated servo drives and hardware to track the motion of the sun. Thanks to a clever article by an experienced eclipse observer, the good news is that this design doesn't require a tracking mount (1,2). It can be done with a carefully selected lens, a programmable camera that can take sequences of images, like the Raspberry Pi, and careful pre-planning. All this will be described in detail below.

Imaging Sunspots

Sunspots are cooler areas of the Sun’s surface caused by massive changes in the Sun’s magnetic field. The magnetic field can be so strong locally that it keeps some of the heat within the Sun from reaching the surface. These cooler areas appear as dark spots on the bright sun that are often larger than the size of the Earth, as shown above. An individual sunspot can last anywhere from a few days to a few months. The number of sunspots goes through a regular cycle that starts over about every 11 years; the number increases from nearly zero to more than 100 and then decreases back to near zero as a new cycle starts. This 11-year pattern is called the sunspot cycle. We are now in the 25th cycle since record-keeping began in 1755. This cycle is expected to peak in 2025, so it is a perfect time to start monitoring sunspots.

Scientists closely monitor sunspots and related solar flare activity because they can greatly affect radio communications on Earth and can also have an affect on the lifetime of satellites in low-Earth orbit. As an amateur solar astronomer, you can monitor sunspot activity yourself using this Raspberry Pi Solar Camera. Similar to the process for capturing images of the solar eclipse, a sequence of several images of the sun are taken on any clear day, then these are combined, using free software applications, to produce enhanced images of the current sunspots. One of the best ways to keep track of sunspots is to follow Spaceweatherlive.com and follow the Solar Activity there. They also have a free app that can be downloaded from the app store. It is available for both iOS and Android. This is a very handy one as you can check for active regions quickly and photograph them.

The diagram shows the components of the RPi Solar Camera that will be assembled in this Instructable. The basic hardware consists of a solar filter to protect the camera sensor from bright sunlight, a lens, an optional C-mount lens adapter, Raspberry Pi CCD camera module, a Raspberry Pi computer, an LCD viewfinder monitor, and a battery power supply. Theses hardware components are physically connected into one unit that can be rigidly mounted on a tripod so it can be easily aimed at the sun. The selection of each of these components will be described below.

One of most important components of the system is a solar filter. This is a thin sheet of special filter material that goes in front of the lens. The filter is aluminized and appears opaque when you hold it up in normal light. This is essential to reduce the intensity of the incoming light from the sun so it does not destroy the sensitive CCD camera sensor. While directly looking at the sun during the eclipse progress will cause eye damage, it is safe to indirectly view the video image produced by the camera.

There are several types of filters made of glass or on plastic sheets. The two most popular are plastic sheet filters made by Baader Planetarium and Thousand Oaks Optical. I have tried both, and they both work well, but I am going with the Baader filter as it has been preferred by several experienced astrophotographers in references given at the end of this Instructable.

As shown in the picture here, the filter comes as a square sheet that has to be cut to size with scissors. The simplest method of mounting is to just tape a piece of filter across the front of the lens, making sure the lens opening is fully covered. This has the disadvantage that it can easily slip off as you orient the camera or it can blow off in a light wind.

You can find many ways to mount the filter material online. Most use simple cardboard to make a sleeve and tape, or foam core, or modifying a lens cap by cutting a hole in it. Here is suggestions, one by Baader:

1. https://www.baader-planetarium.com/en/downloads/dl/file/id/337/product/3039/how_to_make_your_own_solar_filter_for_cameras_binoculars_and_telescope.pdf
2. https://www.instructables.com/DIY-Solar-Filter-for-Telescopes-and-Cameras/

In the end it does not have to be fancy, but it should be able to be put on and off easily since it will need to be quickly taken on/off the front of the lens during totality. This necessary for a short time when the eclipse is total, as it will appear dark except for the corona around the perimeter. Then, after totality, it is put back on. This can be difficult to do effortlessly without jostling the camera lens unless the filter can be removed easily and the camera and lens assembly is held rigid. There are lots of stories by veterans about the lens being jostled in this process and needing some manual realignment that distracts you from observing yourself during key moments.

Two Reminders:

1. Do NOT look at directly at the eclipse without protection while building and using anything pointed at the sun. DO NOT ignore the warnings about not staring directly at the sun, even for a few seconds. That can cause permanent damage to your eyes. Because there are no pain receptors in the retina, you won’t feel it while it’s happening.
2. There have been some tempting suggestions to try to use your iPhone camera pointed at the sun without having a filter on the front of the camera lens. DO NOT. This usually leads to destroying your expensive camera chip.

Eclipse Imaging

The next design decision to consider is lens selection for eclipse imaging. This turned out to be more difficult than expected as there were limited lenses that are both compatible with the RPi that are also ideal for eclipse imaging.

There are two classic views of a total solar eclipse, as shown in the examples here. The first figure shows a sequence of images as the moon progression in front of the sun, with one image of the sun in totality is in the center of the sequence. The second figure shows one larger solar image with the corona around the rim of the sun, only seen during a total solar eclipse. As mentioned earlier, the goal of this Instructable is take the first, the sequence version.

There are many articles on line about lens selection for astrophotography that explain the best choices for solar imaging. I've listed several at end of this Instructable in case you want more details. The focal length of the lens determines how big or small the sun will appear in your image. Because the sun lights up the entire daylight sky, we think of it as huge. But it actually appears in the sky to be almost the same size as the Moon. That's why it perfectly blocks out the entire sun in an eclipse.

The third figure above shows four images of the sun taken using different focal lengths using the Raspberry Pi Camera. To experiment with different focal lengths I used a variable telephoto lens to make it easy to show the variation in size depending on the lens focal length. The images are not very clear because they were taken on a partly cloudy (winter) day.

Remember, the idea of the drift method is to take a sequence as the moon passes in front of the sun, and get a sequence of images starting uncovered, then blocked sun in the center, and then unovered again as the moon passes away. So pick a focal length that is a compromise between the images being small enough to have a multiple image sequence before, during, and after the moon passes over the sun, but also large enough to show some detail of the corona in the middle during totality. Looking at the largest, the 200mm, it is to large because the sequence would only have a small number of non-touching images of the sun before the frame was filled. On the other end, something in the range of 50mm focal length should work well.

Sunspot Imaging

The criteria for the best lens for sunspot imaging is almost the opposite as for the eclipse case. The process for sunspot imaging is to collect a sequence of one image after the other, but unlike sunspot imaging of a path, all the images should be centered on the sun, and the sun image as large as possible to show sunspot detail. After collection, the sequence of images will be processed by a filtering algorithm to filter out noisy variation areas and emphasize the darker sunspot areas. It is clear that for the sunspot case, you want the longer focal length, 200mm or more to end up with one large, centered image.

Just to note, the first 50mm example has a red tint because it was taken using a Thousand Oaks filter. The other three were taken with the Baader filter. Note also that the four images above were taken using the Raspbery Pi Camera Module and the libcamera software that will be described in a section below.

Eclipse Lens Selection

Based on the results above, the ideal lens for imaging the solar eclipse is one with a lens with a 50mm focal length. The most popular lens that has become the de-facto standard for most users is the low-cost Raspberry Pi camera, shown in the first row. These only cost from $6-$10 and work amazingly well for general purpose applications, like announcement devices or robot obstacle monitors. Unfortunately, it has a very tiny hard-mounted lens that lens with a fixed lens that is about 5mm. The first image shows the size of the sun using this lens in a RPi computer. Because the focal length is very short, the image very small, so this lens is obviously not suitable.

There is a wide variety of other lenses available for the Raspberry Pi camera, but most have focal length ranges between 5-25mm and thus too short for solar imaging.

The second row shows an exception, a ArduCam lens with a 50mm focal length. It comes with a standard C lens mount that will screw into the Raspberry Pi camera module, also shown in the same row. This appears to be the best available option for Solar Eclipse Imaging

Sunspot Lens Selection

A lens with a long focal length of at least 200mm will work for the sunspot imaging. The third row shows a traditional 70-300mm zoom lens usually used on a DSLR camera. You will find many similar lenses with long length available at good prices on eBay. If you can find a fixed focal length telephoto versus variable, it will be shorter and lighter. You many already have high quality zoom lenses that may go with a long focal length that can be used if they have a focal length of at least 200mm. Many of these lenses may require an adapter to go between a standard DSLR Cannon or Nikon camera mount and a C-mount on the Raspberry Pi Camera. An example is shown in the bottom right photo. You can find these on Amazon, but be careful to order the correct male/female connections.

When you photograph something outside of our atmosphere, there is a fair amount of air between you and the subject. As a result, regardless of whether you are using expensive filters, lenses and CCD sensor, the sun is only, at its best, "kind of" sharp. Keep that in mind when thinking about searching for a relatively inexpensive used lens on eBay versus a super expensive new lens you may not use again.

As shown in the diagram, the hardware for this Instructable is relatively straightforward because it primarily involves screwing together COTS modules. Note that the Raspberry Pi model 4 is being used, versus the 5, because the 4 is more compatible with the existing camera software.

The camera usually comes with the ribbon cable plugged in. As a first step, disconnect the ribbon cable from the camera board and insert it into the correct connector on the RPi board. This is because the connector on the RPi will become inaccessible after the next step. I cannot emphasize taking care to make sure you put the right side of the cable into the correct connector. Typically the correct orientation is with the blue part of the ribbon cable facing towards the USB ports. I suggest you check out instructions about this if your first time, because it is easy to insert backwards. The RPi Camera Forms say over and over this step is the biggest source of the camera not working by first time builders. https://projects.raspberrypi.org/en/projects/getting-started-with-picamera/2.  I proved that point to be true!

The next step is to assemble the case that comes with the LCD display. This step can be optional, but it provides a convenient way to view the image on the back of the camera. This involves plugging the display into GPIO connector on the Raspberry Pi 4 and attaching a special connector that comes with the display. Then, attacht the pre-cut plastic sheets for the case with the standoffs that comes with the display.

Next, mount the Pi Power Supply board on top of the the assembled case with standoffs mounted on the predrilled holes. The power supply comes with a short connector to connect the supply to the RPi board. This step can also be optional, but it provides a way to power the camera without having a wired supply cord in remote locations.

The next step involves a small modification of the plastic sheet that mounts on top of the Pi Supply to hold the camera board. You need to drill 4 holes in the top sheet of the Pi supply and use the standoffs to mount the RPi camera board. You can mark the position of the new holes by sitting the camera board on top and marking through its holes as a template. Then use the standoffs that come with the camera to mount it on top of the modified plate on top of the supply. At this point, the flexible ribbon cable that has been loose, can now be plugged back into the camera module. This completes the basic camera structure.

Next, attach the lens. First unscrew the short focal length lens that probably came in the RPi camera module. Then either attach the ArdaCam 50mm lens, or if you are using another zoom lens, insert the necessary lens adapter by screwing in the C-mount threaded side. Then screw the lens into the large opening on the other side of the adapter. Finally, the solar filter can be attached to the front of the zoom lens.

The final assembly should appear as the one in the bottom of the diagram.

It is very important to have a reliable way to rigidly mount the Raspberry Pi Camera onto a tripod so it can be conveniently positioned to view the eclipse. In this step I show a way to construct a custom adapter using easily available hardware mending plates. These are found in hardware stores by the common angle brackets. First use an F size drill (.257") to drill a clearance hole in the middle of a 4.5" steel mending plate, as shown in the first image. Then solder a 1/4-20 hex nut over the hole. Then solder this plate to the two brass standoffs that have been removed from the RPi Power/RPi 4 Case. Once soldered together, the strap can be screwed back into the case. If you do not solder, this could also be carefully attached with epoxy glue.

Second, bold a 3.25" right angle bracket to the above plate using a short 1/4-20 bolt, as shown in the second picture. I drilled a hole for a second 6-30 screw keep the two straps from rotating.

Once completed, as shown in the 3rd image, the other side of the angle strap will fit onto the standard 1/4-20 bolt that is on the top of most tripods and snugged onto the tripod by adding a 1/4-2- wing nut.

This Instructable uses the Raspberry Pi 4 computer (https://amzn.to/3TApzIU). The 64 Bit operating system was used on a micro SD card, versus the 32 bit version as the 32 bit version, which some problems with the Raspberry Pi camera library.

Fortunately, there is a great software library, called libcamera, that is an open source Linux community project, that drives the camera system directly and supports making complex camera systems very easy. The libcamera apps are command-line applications supported by Raspberry that make it easy to capture images and video from the camera.

If you are new to the Raspberry Pi world, you may not be familiar with the the LINUX operating system used on the Pi. You will only need to know a few basic commands, which are outlined here if you need help: https://www.circuitbasics.com/useful-raspberry-pi-commands/

When running the most recent version of the Raspberry Pi OS, the basic libcamera-apps are already installed. The Raspberry Pi cameras will also be detected and enabled automatically without having do activate.

To do an initial test, there is asimple "hello world" application which starts a camera preview stream and displays it on the screen for 5 seconds: libcamera-hello

You can also add a duration or time out in milliseconds by adding -t followed by a number of time to perform a capture. If you pass the value 0 (this is a zero, not an o) the duration will ‘run indefinitely’: libcamera-hello -t 0

To capture a full resolution JPEG image use: libcamera-jpg -o test.jpg The -o (an o, not zero) means an name output file name follows. This will display a preview for about five seconds, and then capture a full resolution JPEG image to the file test.jpg. An example is shown above of this First Light in the camera.

The -t <duration> option can be used to alter the length of time the preview shows, and the --width and --height options to change the resolution of the captured still image. For example: l

ibcamera-jpg -o test.jpg -t 2000 --width 640 --height 480

If the image is in the wrong orientation you can add a --hflip or --vflip

Time-lapse Sequence

A time-lapse capture is where we capture an image at regular intervals, perhaps every minute, hour or day, and then reassemble them into a video where we play them back at a much faster rate. You can use libcamera-still to capture the images we need out of the box. Then you can introduce the --timelapse option to specify the length of time, again in milliseconds, between each of the time-lapse captures.

Then use -o to give the name of the output file or files. For time-lapse captures, we can’t give all the images the same name so we use a special syntax that includes an image counter. For example, -o capture_%04d.jpg means that all the files are named ‘capture_’, followed by a counter, and then .jpg. %04d specifies how the counter is formatted, in this case the 0 means to add leading zeroes to the number and the 4 means ‘so that every number has at least 4 digits’. This is useful so that listing your image files will return them to you in chronological order.

Here is an example:

libcamera-still -t 300000 --timelapse 60000 -o eclipse%04d.jpg

This will run for 5 minutes (300,000 milliseconds), capturing an image once every 60 seconds, and they’ll be called eclipse0000.jpg through to eclipse0004.jpg.

Assembling your Images into a Video

There is a tool called FFmpeg which is capable of turning your sequence of still images into a video as follows:

ffmpeg -r 2 -i capture_%04d.jpg video.mp4

Note how this formats the name of the input files with the special % syntax in the same way as you did for libcamera-still. The -r parameter gives the frame rate of the output video, 2 frames per second in this case. We’ve chosen the output file to have the MP4 format and called it video.mp4.

Capturing when a key is pressed

In the case of our eclipse event, rather than doing regular captures, we want them to start in response to a trigger event, like pressing a key. You can set this up by adding a couple of more options:

–datetime. Use this instead of -o to name the output file after the current date and time. The format will be MMDDhhmmss.jpg, where MM and DD are the month and date number, and hh, mm and ss are hours, minutes and seconds.

-k or –keypress. To indicate capturing an image when ENTER is pressed on the keyboard. Type X and press ENTER to quit.

So the command to use is this:

libcamera-still -t 0 --keypress --datetime

This runs the capture indefinitely, so we’ll have to type X followed by ENTER to quit (or press CTRL+C). Files would have names like 0405102742.jpg, meaning ‘10:27am, and 42 seconds, on 5 April’.

Putting The Functions Together to Capture the Eclipse Sequence

The nice thing about the Pi libcamera library is that they can be easily used for what is needed to capture the eclipse without writing python code or a script. They can set up the camera to capture time lapse images of the eclipse starting when a key is pressed and then after the eclipse the sequence of images can be converted to a video.

There will be suggestions on how to set up the interval timing for the eclipse in the next step, but it is essentially going to be a total period of about 7 minutes total: 2 minutes before, 2.5 in totality, and 2 after, and the

More Information

https://www.raspberrypi.com/news/raspberry-pi-camera-module-still-image-capture/

and Raspberry

The libcamera source code can be foundhttps://github.com/raspberrypi/libcamera

Most past eclipse observers make one key suggestion. First and foremost, make your own experience the priority. Enjoy the eclipse event with your own eyes. Don't get distracted trying to maintain some piece of gear that you have set up to record the experience. A key suggestion they all make is to practicing ahead of time to avoid fumbling around with some unexpected focus adjustment change, slipping filter, or giggly tripod. Unfortunately, to get the desired sequence, with the total image in the center, it is necessary to remove the filter shortly before and after totality. That introduces a lot of opportunity to fumble and miss watching with your own eyes. So keep this in mind with practicing and planning.

Drift Method

One of the best pre-planning suggestions is called the Drift Method (1,2). I discovered this in YouTube videos by Destin and Dr Gordon Telepun. The best way to understand it is to watch the video linked below. But here is the basic process:

1. Before the day of the eclipse practice by starting with the max zoom level of the lens and your camera aimed at the sun+filter so you can watch it cross on a monitor screen.
2. Time the length of time it takes for the sun to drift from the left to the right side of the screen.
3. Experiment with the zoom adjustment until you can get it so it takes the sun about seven minutes to get from one side to the other. This is based on the fact that totality of the sun lasts 2.5 minutes. So you want to capture a path of images that starts about 2 minutes before, 2.5 in totality and 2 after, or about 7 minutes total.
4. You are going to have to remove the filter a few seconds ahead of totality and replace it quickly after, or those frames will be black when you replay. So practice the series of hand movements for filter changes. While it might seem silly, it will make a huge difference in execution when you literally have seconds to do it right!
5. Use the Solar Eclipse Timer app (below) that will "TALK" You Through The Eclipse based on your geolocation and time.
6. Set up the interval timer setting in your Raspberry Pi for a total duration of 7 minutes, taking pics at an interval of about 2 every second.
7. On the day of the eclipse you just set it up, use the Timer app to know when to start the camera interval timer, then just let the sun drift while you watch the eclipse and just take a few moments to remove the timer.
8. Enjoy watching the eclipse with your own eyes+filter glasses

Here are some links showing this process by an experienced eclipse veteran:

• A terrific YouTube video on how to do the Drift Method: https://www.youtube.com/watch?v=fmg01KYfjc0
• Suggestions on how to set up time lapse interval: https://alpinelaboratories.com/pages/how-to-holy-grail-time-lapse-a-solar-eclipse_l
• Solar Eclipse Timer ($1.99 !): https://www.solareclipsetimer.com/

Results (bad weather!)

Unfortunately, the weather on April 8, 2024 turned out to be cloudy over many areas of the total eclipse path, including my location. So my results were very limited. I attached one picture here. The blurriness is because it was take through clouds. Onward to 2044, or maybe 2024 in Australia. The good news is that I was very happy learning to put together the Raspberry Pi Solar Camera which I plan on now using to start exploring sunspot imaging, as described in the next section.

In addition to capturing the Total Eclipse images, the same Raspberry Pi Solar Camera can be used to capture images of sunspots on the sun. The only change to the Raspberry Pi Solar Camera hardware apparatus is to change the lens from 50mm to a longer focal length of 200mm or longer. That will fill as much of the image frame as possible to make small sunspots as large as possible. When taking the eclipse sequence, you collected images over about 8 minutes to capture the sun before, during, and after the moon passed in front of it. When doing sunspot imaging, you need a sequence of several images that can be close in time, but all nearly centered on the sun. This will provide samples with that each have slightly different variations due to atmospheric turbulence, such as the one above. Once collected, you can process the sequence with software applications that will "stack" the images and filter out the noisy irregularities. Turbulence and noise in each image will disturb the dark regions. But if you shoot many photos of the same subject, stack them together, and filter and average them, the result is far better than that of a single frame. The noise and graininess are filled in, and the image will appear much smoother and clearer, as shown in the second image. The third image shows an example of using a much longer focal length to close up a small sub-area of the sun with interesting sunspots.

Several generations of image stacking software have been developed specifically for this purpose. Several of the most recent can process video streams instead of individual sequential files. In addition to still image capture, the Raspberry Pi camera software also has a video capture capability called libcamera-vid. This will display a preview window, and the encoded bitstream will be written to the specified output file, named test.h264. For example, the following command will write a 10-second video to the file: libcamera-vid -t 10000 -o test.h264

Because the stored video can use more memory than available in the typical Raspberry Pi, the process here for sunspot capture is to use the libcamera function to capture the video, but transfer the file to a laptop for the stacking process. Most of the older stacking software is old and klunky, but there is a newer function called ASIVideoStack that is in a suite called ASIStudios that makes the process fast and easy. It can process gigabytes of data in less than a minute. More information is available here: ASIStudio

By using the above process on sunspot video you will be able to produce good quality sunspot images like those shown above.

Solar Eclipse Related Information

Here are two articles on the "drift method" describing how to automate the collection of your total solar eclipse sequence

1. https://www.youtube.com/watch?v=fmg01KYfjc0
2. https://www.youtube.com/watch?v=Qp57Z_vmOwE

This article compares the Baader vs Thouseand Oaks Solar Filters

https://astro.ecuadors.net/baader-astrosolar-vs-thousand-oaks-black-polymer-solar-filter/

This is a link to a highly recommended solar eclipse timer app mentioned above for your iPhone ($1.99):

https://apps.apple.com/us/app/solar-eclipse-timer/id1203105865

Below are a few excellent articles on viewing and imaging the eclipse. They are aimed at using a DSLR camera, but they still have useful hints:

https://eclipse.aas.org/imaging-video/images-videos

https://www.mreclipse.com/SEphoto/SEphoto.html

https://www.bhphotovideo.com/explora/photography/tips-and-solutions/how-to-photograph-a-solar-eclipse

https://www.highpointscientific.com/astronomy-hub/category/solar-and-lunar-eclipses

https://www.youtube.com/watch?v=9StbAas1PQQ

Information about Sunspot Astronomy

https://www.lightstalking.com/photograph-sunspots/

https://stargazerslounge.com/topic/153712-simple-white-light-solar-imaging/

Space Weather

https://spaceweather.com/

https://www.swpc.noaa.gov/products/solar-cycle-progression

More Complicated Tracking Camera Mounts

There are other recent Raspberry Pi astrophotography projects that you may want to check out for more suggestions. The first two describe an incredible, but costly project, the second is more versatile and complicated. Keep in mind that these are aimed at general astronomy viewing, so they have more precision aiming and resolution objectives than necessary for eclipse and sunspot viewing. That impacts the optics as well as more general servo driven alt/az mounts.

https://www.raspberrypi.com/news/solar-photography-with-oneincheye-the-magpi-138/

https://hackaday.com/2023/10/17/solar-camera-built-from-raspberry-pi/

https://www.raspberrypi.com/news/mini-observatory-the-magpi-140/