Preparations for this eclipse started already in 2019, when I first visited the villages of Cetina and Sisamon. The villages are just a few kilometers apart and are located between Madrid and Zaragoza. Especially the vicinity of Sisamon profed to have great spots for night time observations, as light pollution is pretty low. The same spot I observed in 2019 was also a perfect spot for the solar eclipse, as it lies approximately 1000m above sea level in a high plane. To the west, only some distant hills are seen, reaching 2 degrees above the horizon at maximum. This was crucial, as the totality would happen with the sun being only 7 degrees above the horizon.
Thanks to the mayor of Sisamon and my sister in law to communicate with him, I got the permission to setup my observation base at this very location. He also supported me in having my complete equipment without any obstacles and disturbances, despite a good 100 locals joining the event. They were all essential for the emotional experience, as many of them started cheering and shouting when totality arrived. A big THANK YOU to everyone involved to make this a perfect day!
According equipment, my primary goal was to get the shots for the Eclipse Mega Movie project (a Sonoma State / NASA project, I participated the third time). Then, some overview and especially landscape views of totality were on my plan, to also showcase the shadow of the moon.
In Spain at the eclipse site I got a couple of times the question, how the sun will look like visually and on their own camera. The majority was referring to their mobile phone when thinking about a camera. So in general, my reply was rather disappointig to them. You know why? It is easy to explain:
The size the sun as seen from earth, is half a degree in diameter. (Luckily, the moon is exactly the same size with minor variations, so we can witness solar eclipses 🙂 )
Mobile phone cameras have typical angles of view in the range of:
120 degrees in ultra wide angle camera (12 mm lens on full frame camera)
80 degrees on the main camera (wide angle) (24 mm lens on full frame camera)
10-20 degrees with tele camera (120-240 mm lens on full frame camera)
This means, that on the main sensor, the sun will only be a small circle with less than 1/100th of the image diagonal. If you are lucky and own a mobile phone with optical tele (zoom) with 10x or more and a 50 megapixel sensor, the sun will show up with some / reasonable size on your photo. Still, it will not compare to decent tele photo lenses or telescopes simply due to optical limits of the tiny lenses in the mobile phone cameras. The key reason is called diffraction (waves passing through an aperture will alter their direction by some extent), which limits optics from exceeding resolution depending on the aperture size of the lens. A large mobile phone camera lens with i.e. 10 mm diameter has a resolvin limit of approximately 12 arcseconds (1/300th degree). In comparison, a larger tele lens or smaller telescope with 72 mm lens diameter would be able to resolve 1.4 arcseconds.
To break it down, the following table has some technical information about the sizes of the sun on different cameras:
Mobile phone camera
36mm equiv. Focal Length
Diagonal FOV
Angular Resolution (50 MPx sensor)
Size of sun
0.5x ultra-wide
12 mm
120°
0.0118° / Px 42.33″ / Px
42 Px
1x main camera
24 mm
80°
0.0078° / Px 28.22″ / Px
64 Px
10x tele
240 mm
10°
0.0010° / Px 3.53″ / Px
510 Px
Size of the sun on mobile phone camera with 50 megapixel sensor
Probably easier to see are the real world examples… I took these images using the mandatory solar filters ahead of the 2024 eclipse. I wantet to see, how much of the corona would fit in and how precise the tracking has to be for the required shots.
This demonstrates, that on the mobile phone, the sun is only a tiny dot. Even the tele camera is not showing details due to the optical limits. To photograph the sun with some details of the surface, a larger optic is required. But what a telescope or a large tele lens is not capable of to record is the whole scenery and the emotional impact of a solar eclipse. This would be the perfect use of the mobile phone.
Final word: No matter what you want to capture during a total solar eclipse – prepare everything to run as independent as possible. The few minutes of totality are best recorded in your own memory. Do not let the technical gizmos distract you from this uniqe moment!
The sun follows a regular cycle of activity and quietnes. This cycle takes 11 years to start over again. By chance, the 2017 total solar eclipse was at the solar minimum and the 2024 total solar eclipse was at the most active phase – the solar maximum. Comparing the images I took during totality of the two eclipses, the solar corona also reflects this.
During the solar minimum, the corona looks more structured. At the poles, the corona shows a well defined pattern resembling the magnetic field lines.
In contrary, during the solar maximum, there are more jets and streamers (also at the poles) but there are less structured patterns. Especially the inner corona looks rather chaotic compared to the quiet sun.
It will be fascinating to compare these images with further images from other eclipses…
The main reason to travel to the US and go on a road trip to follow almost the entire golf coast from east to west was to see and photograph the total solar eclipse on April, 8th. My plan was to image with a total of 9 cameras. Most of the cameras got a custom made (see my 3D design here: https://www.thingiverse.com/thing:2431974) flip-away solar filter, to facilitate the on and off during totality. As I was up to share my photos with the scientific community through the Eclipse Mega Movie project, like in 2017 (https://eclipsemegamovie.org/), I had some constraints to follow for my setup.
Therefore, the complete setup, which should be mounted on 4 independent tracking mounts, was:
Sony A6000 full-specturm modified with 80/600mm APO
Sony A6400 with 72/435mm APO for longer exposure sequences
Sony A6400 with 72/435mm APO for shorter exposure sequences
Sony A99ii with 35mm lens to capture the eclipsed sun with planets and hopefully a comet
Sony A58 with 135mm lens
Sony ZV-E10 with 100/1000mm maksutov
QHY485C with 50/242mm APO for a totality video
2 GoPro cameras for scenery
Test setup with almost all cameras
With bad luck, the airline was incapable of delivering one piece of luggage with my primary tracking mount within almost 3 weeks. Therefore I had to reduce the actual setup for the eclipse day in parts. Furthermore, it was quite unsure, whether observing the eclipse was even possible. A wide stretched cloud system covered large protions of Texas. In the morning, there was not even a patch of blue sky visible. Luckily, the clouds got less and less and even the one cloud covering the sun a few minutes before totality moved away. So we finlly could observe the eclipsed sun with an almost perfect sky. In the end I was able to record the required images, totaling to more than 400 GB of data.
So i started a new imaging run with higher magnification (1320mm instead of 564mm) and more sensitive camera. The resulting image of almost 13 hours data shows a lot more of the surrounding and weak features, even though, the same imaging location was used. The same Bortle 6-7 location was used, observing low above the light cone of the city.
On November 04 and 05 a few Coronal Mass Ejections were released from the sun (a coronal hole is facing our direction). Yesterday evening at 17:06 CET the solar storm arrived and created an impressive aurora display. The most fascinating fact is, that conditions were so intense, that even in southern Austria (below 47 degrees North) the sky in northern directions was colored red! It was an amazing visual experience!
The pictures below were captured with my mobile phone. The aurora was so bright, that even handheld images were possible!
As I am imaging in a rather severe light polluted location, where the landlords have installed significantly stronger light fixtures, I am plagued with strong gradients and a circular pattern in my images. These gradients won’t calibrate out with bias, flat and dark frames. I tried several approaches to get rid of them. I added a dew shield with no significant improvement. I added a light blocking hood to the back of my Newton scope with only marginal changes. I created flat frame images in different combinations (with or without dew shield, high and low exposure target, vertical or angled scope position, …). All with no significant changes.
Then I located several light leaks in my imaging train. The worst leaks were at the focuser base, the Off-Axis Guider and the mounting adapter between camera and filter wheel. After closing all the gaps, the results improved. But still the gradients were clearly visible in moderately stretched images.
Focuser base has no light shieldingQuite intense light leak made visible by flash light pointed at focuser baseLight shining through at camera flangeCore of imaging train, showing Off-Axis Guider cover to block light
So in all the past 3 years using this setup, my only chance to create acceptable images was to reduce as much of the gradients as possible in post processing. To accomplish this I had to set several hundred calibration points for background elimination in Pixinsight (loosing any chance to process weak background nebulosity or the like). This was a tedious work, as all calibration points had to be set manually (you may not have any stars or parts of nebulosity, a galaxy within the calibration point rectangle). And still there remained some residue if the gradients. So the results were not of the quality I strived for.
Typical raw image before calibration, stretchedImage after calibration, stretched, showing gradient and ring patternImage crowded with 800+ calibration markers for background eliminationExample of M100 after final processing (including background elimination)
Finally, I technically analyzed my scope and imaging train to check for defects like vignetting. I could not find anything, causing such a pattern. So I concluded, the only culprit possible could be the coma corrector.
History: After several years using an economic GSO corrector, where stars have never been perfectly small and round in my setup, I switched to the Gyulai Pal designed TS-GPU corrector. Images have been really nice. But back then, I used a camera with an IMX183 sensor (15.8mm diagonal). A bit later, I switched to the IMX571 sensor, which has a significantly larger active area with a 28.3mm diagonal. Initially, I could capture images, which calibrated well. Though at this time, the street lights were far less bright and not LED based. So the filters could get rid of the stray light and light pollution. Now, with the close to 4x stronger LED street lights, everything changed.
As I (hopefully) closed all the gaps where light may enter, the front of my telescope should be the only place where light should enter my imaging train. Even with a dew shield it might be possible that light may shine to the front element of the TS-GPU corrector. Either direct or by reflection of the inside wall of the dew shield (which is not the deepest and blackest black possible), the corrector may pick up some stray light. To rule this possibility out, I attached a 10mm extension tube to the front of the corrector. But unfortunately, there was no change in resulting images.
I could borrow 2 types of coma corrector from astronomy club fellows to test my assumption. So to test, I have one of each corrector: my TS-GPU, a Baader MPCC III and a TeleVue Paracorr. During the last weeks I captured M16 with all 3 coma correctors in L(RGB) and H-alpha from my home with the identical setup.
After calibration and stacking, I applied a background neutralization with only 8-10 calibration points to remove the large scale gradients from light pollution. Then I simply stretched the histogram of the images with automatic screen transfer function in Pixinsight and placed the 3 images of each filter set side by side for comparison. Well – I think, there is not much to say. Only the GPU coma corrector leads to the image defects.
Comparison of M16 in luminance with TeleVue Paracorr, Baader MPCC III and TS-GPU coma correctorsComparison of M16 in H-alpha with TeleVue Paracorr, Baader MPCC III and TS-GPU coma correctors
Observations:
the TS-GPU corrector is with 10cm quite long.
the focus position of the TS-GPU corrector lies just a few millimeters above the inner limit of my focuser
the TS-GPU corrector protrudes in the tube by 2.5cm (1 inch)
both of the other correctors (TeleVue and Baader) require the focuser at the outside limit or even beyond (using extension tubes).
the TeleVue Paracorr is 7cm long- the Baader MPCC measures less than 3cm- At focus, the Baader and TeleVue have their front lens element way inside the focuser tube. Therefore, no stray light may enter the corrector
Conclusion:
In light polluted skies, especially with nearby (street)lights, which possibly shine in the telescope, you have to be extra careful. Any stray light may cause severe trouble in astro photography. Locating the light leaks may get intensive and very time consuming. But it is well worth it to spend the time. Your efforts will pay off in post processing and final image results!If you suffer from effects comparable to mine, you should not only hunt down the obvious light leaks (using a strong flash light or even sunlight). You should also check each and every optical component, if at some point stray light may enter your optical train. Try to close gaps and holes and shield your system as good as possible!
On Sunday, May 1st, I was lucky to have the ISS transit the sun only a few kilometers away. Weather played with my plans as well. So i packed my solar scope and drove to a place right in the center of the transit line. The transit itself is a very brief event. This particular one lasted for less than 2 seconds. So everything hat to be well set up before the clock reached 08:24:22 CEST.
This image is a combination of 15 individual images captured in 1.02 seconds. The solar surface was further enhanced by a stack of 880 frames adjacent to the transit itself.
This is my first image of Messier 90. It is not yet as good as I would like it to be. Which is due to bad weather preventing further imaging. As the moon is already too bright, I will have to postpone further imaging at least to the next new-moon phase. Nevertheless, this image shows already a beautiful spiral galaxy with its companion.
Image data: Date: 2021-04-15 – 2021-04-16 Location: Graz, Austria Telescope: 10″ f/5 Newtonian with GPU corrector (1250mm focal length) Camera: QHY183M @ -20C Filters: Optolong RGB + Baader UV-IR-Cut Guiding: MGEN-II with off-axis guider Exposures: UV-IR-Cut: 45x120s, Gain 0, Offset 15 R 30x120s, G 25x120s, B 23x120s, Gain 10, Offset 15
During the last years I frequently ran into trouble with the stock Sony batteries. Neither of the camera – battery combinations I had, were capable of imaging more than approximately 4 to 5 hours (some cameras drained their batteries within less than 2 hours). So I tried to determine the optimum means of powering a Sony camera for several hours without the need to change batteries. Here is, what I came up with:
Option 1: Batteries with increased capacity Several after market companies offer compatible batteries with increased capacity. These batteries are also offered at more than competitive price tags. In my experience, most of these batteries do not provide the capacity as imprinted. There are units, which significantly exceed the stock batteries. But you may also get a battery, which is outperformed by the stock battery – even though it is offered at twice the capacity. If you are lucky and you have a well performing battery, you may extend the time in operation by 10%-50%.
Pro
Con
– economic price – up to 50% longer operation – no external units required
– does not last a whole night – capacity labelling may be misleading
Option 2: USB power supply Several – and at least the new models – have a USB port, which is capable of powering the camera during usage. This is a great way to have your camera last for hours. This is also a truly economic way, as you simply plug a USB power bank to the camera. Be aware, that you may need a special splitter cable, to simultaneously run a trigger and the USB power supply through the Multi-Port connector! See here, how such a cable may look like: Combined charger and trigger cable for Sony mirrorless cameras like A6400 But to my experience with a Sony A6400, the USB port is not capable of providing sufficient power in heavy use situations. When I had the camera shoot 3000-7000 images in 1 second intervals, I ended up with a (almost) drained battery. So the camera was constantly discharging and charging the battery. The discharge rate was higher than the charging rate. This caused the camera to significantly heat up – which is highly discouraged in astrophotography! Further more, at least the battery is set under unneccessary stress.
Pro
Con
– really cheap – may last the whole night – may be “hot plugged”
– camera may heat up – special cable may be required – battery stress
Option 3: Vertical Grip The majority of the higher end and high end cameras may be equipped with a vertical grip unit. The vertical grip units are typically fitted to the battery slot instead of the battery. To power the camera, the vertical grip incorporates a tray for 2 battereries. This doubles the capacity possible. But depending on the camera, if you keep the remote trigger port constantly in focus / pre-fire mode, the camera may not switch to the second battery. So you may end up with a camera in power-safe mode and an exhausted battery as well as a fully charged one… Further more, you have to keep in mind, that the vertical grip units are quite heavy (adding a couple 100g in weight). This may be an issue to your setup!
Pro
Con
– no external components – easy to handle
– vertical grips are not quite cheap – battery capacity only doubled – higher weight
Option 4: External power supply Some Sony cameras have a power in connector. This is a proprietary connector, which was already in use back in the Konica/Minolta aera. The connector is flat, with both poles on the opposite sides. On one side, there is a small bar, to prevent reverse plugging. So, technically, no big deal. Unfortunately the connectors are not available individually. But nowadays, you get really cheap power supplies with matching connectors online. If you are a DIY person: it is really easy to build or use such a connector; Simply provide 7.2V from a mains supply, step converter or lithium batteries ;-). To my experience, in-camera batteries are disconnected from the camera, when you plug in the external supply. So, if you plug or unplug the external supply, the camera restarts. If you leave the plug in the camera and cut the supply voltage, the camera is not operable (due to disconnected battery)
Pro
Con
– easy to handle – easy to build yourself – cheap – perfect for studio / fixed setup
– designed for mains connection – does not charge in-camera batteries – disconnects in-camera battery (no backup, if mains fails)
Option 5: Battery dummy Dummy batteries are a great sollution for long lasting scenarios. You replace the camera battery with a plastic dummy, which has a DC plug. You simply provide 7.2-8V from any means of power supply you have. This may be a mains adapter, USB power bank with step-up adapter, a 12V car socket with step-down adapter or a lithium battery pack with 2 batteries in series. There are even some dummy batteries with included USB to 7.2V converter. But they may lack the power neccessary to drive the camera (some cameras are specified with 7.2V 2A input, which is way above the typical extended USB power scheme of 5V 2.1A. As there are so many ways to provide the power needed, it is a very versatile option. But you have to be careful in selecting the right dummy. Some dummy units do not lock perfectly in the battery slot. So the dummy may fall out of the camera, or it disconnects. Some may have very stiff cables, which pose a lot of stress to the battery compartment lid (which is a true pain to replace!) Hints: – You may never want to charge the dummy battery! This may pose a high risk of damage! – provide a well stabilized, battery-like voltage for best performance – if the dummy disconnects or is not supplied, the camera is off immediately
Pro
Con
– versatile – quite cheap – may last several hours to days
– may disconnect – not every dummy is well made
Summary Depending on the situation, I choose any of these options – or even stick to replacing the batteries frequently. But my personal favorite for long lasting sessions is Option 5 in combination with a 2S 2P or 3P lithium pack (2 or 3 parallel, 2 in series). This power pack provides 7,4V straight off (no converter needed) with far more than 4 times the capacity of the stock battery. Up until now, I never ran into drained batteries, even under -10C conditions after 10 hours shooting.
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