In about 2.5 months I'll travel to Chile to image the solar eclipse. Yay! So today I started trying to take solar images. Better late then never, right? In order to get good images of the Sun I have bought a solar filter which I have placed in from of my telescope. I also put a UV/IR cut filter in the light path so I am sure to only catch light and no other radiation. So far so good.

When I try to make a pic of the Sun it is unsharp. Darn, I forgot to focus. So I waited until tonight and aimed the telescope at the Moon. Without solar filter of course! I was bringing down the exposure time in the Capture tab and and the end took an image of 0.0025 seconds == 1/4000 sec. The DSLR log shows this nicely

[2019-04-13T21:04:07.098 CEST INFO ][ org.kde.kstars.indi] - Canon DSLR EOS 700D : "[INFO] Starting 0.00025 seconds exposure. "
[2019-04-13T21:04:07.098 CEST DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 700D : "[DEBUG] Starting exposure (exptime: 0.000251 secs, mirror lock: 0) "
[2019-04-13T21:04:07.098 CEST DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 700D : "[DEBUG] Mutex locked "
[2019-04-13T21:04:07.098 CEST DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 700D : "[DEBUG] Setting radio/menu widget iso: 1 (100) "
[2019-04-13T21:04:07.098 CEST DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 700D : "[DEBUG] Setting new configuration OK. "
[2019-04-13T21:04:07.099 CEST DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 700D : "[DEBUG] Setting radio/menu widget imageformat: 9 (RAW) "
[2019-04-13T21:04:07.099 CEST DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 700D : "[DEBUG] Setting new configuration OK. "
[2019-04-13T21:04:07.099 CEST DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 700D : "[DEBUG] Using internal bulb widget:eosremoterelease "
[2019-04-13T21:04:07.099 CEST DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 700D : "[DEBUG] Setting radio/menu widget eosremoterelease: 2 (Press Full) "
[2019-04-13T21:04:07.316 CEST DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 700D : "[DEBUG] Setting new configuration OK. "
[2019-04-13T21:04:07.317 CEST DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 700D : "[DEBUG] Exposure started. "
[2019-04-13T21:04:07.317 CEST DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 700D : "[DEBUG] Time left: 0 ms "
[2019-04-13T21:04:07.317 CEST DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 700D : "[DEBUG] Closing internal shutter. "

However, when I open the image in Canon Digital Photo Professional 4, AstroPixelProcessor or PixInsight they all claim that the exposure time was 0.1 sec. So now I wonder if the exposure time really was 0.0025 sec and the image info is wrong, or if the exposure time truly is 0.1 sec. Can anyone enlighten me?


Clear skies, Wouter

I took 10 more images via a capture job at 1/4000 sec and I clearly hear a difference in the time between the closing and opening of the shutter. The difference is visible is the images as well. Most look like this



but three out of ten look like this



All images have 0.1 sec exposure time in their image data. Is this expected behaviour of libgphoto2 (or a known bug) or am I doing something wrong?

For focusing on the sun, make yourself a simple hartmann mask with 2 circular holes and place it over your solar filter. When the pair of images converge, you are in focus. Making use of the tip of the horns of a nearly fully eclipsed sun is a great moment to really nail the focus before the big moment.

When I imaged the 2017 Eclipse, I did not use EKOS. Instead I used Magiclantern and setup to swap in memory cards with different capture routines for the different phases. Partial>Diamond Ring>Totality>Diamond Ring>Partial. (Card 1>2>3>2>1)
Card 1 was setup to take an image every 30 seconds with the intervalometer settings
Card 2 was setup to take rapid burst of 2 bracketed image exposures 1/4000 & 1/60s
Card 3 was setup to take a repeating sequence of 15 bracketed images from 1/4000 up to 4 seconds. 1 stop increase per frame for HDR composition.

It worked out well for me, but not the most ideal setup, while mostly automated, there are manual steps when swapping the cards, and timing is everything. For that reason I will refer you to software some of my peers used, Eclipse Maestro

Enjoy the view!

P.S. Make yourself some filtered binoculars with baader solar film. Totality is safe to view with unfiltered binoculars if you are VERY careful of the timing and cease viewing before the end of totality. Eclipse Maestro will warn you when to replace your filters.

Thanks for pointing me at Eclipse Maestro. That looks like very interesting software even if it is only available for Mac. Luckily I have a MacBook

But apart from that I do wonder about the exposure times of the images I took. I have checked the libgphoto issues on github and cannot find anything.

It looks like gphoto2 doesn't handle short exposures well. I found this email thread

sourceforge.net/p/gphoto/mailman/message/34428305/

and this blog post which I think is from the same author

baheyeldin.com/astronomy/using-canon-eos...lb-mode-gphoto2.html

The command line I used is this

gphoto2 --filename=Test_01.CR2 --wait-event=2s --set-config eosremoterelease=5 --wait-event=2s --set-config eosremoterelease=11 --wait-event-and-download=5s

With this I get an image with an exposure time set to 2 seconds. When I lower the second --wait-event argument to 0.1, I get an image with an exposure time of 0.1 sec. When I lower the value even more, the image exposure remains 0.1 sec. So it looks like gphoto2 is not capable of taking very short exposures. On the other hand, I tried the Canon EOS Utility software and got images of 1/100, 1/160, 1/250 and 1/500 seconds. This is a 1/500 sec image of the Sun taken today



So it looks like I cannot use Ekos for imaging during the Solar Eclipse. I will look into Eclipse Maestro next.

No, it is possible to take short exposures. Just not using BULB. Let me try to take a short exposure with my 600D in a couple of hours and report back.

Please enable logging and attach the Ekos log.

Thanks for the info Jasem. I see the bulb mode selected in the Ekos configuration popup and when I set it to 1/4000 sec then, indeed, a short exposure is taken. Howver, when I then go back to the Capture tab in Ekos and click preview, an image is taken with the exposure time selected in that tab and again I cannot go shorter than 0.0025 sec which equals to 1/400 sec. Here are the logs.


Cheers, Wouter

Hi. Disable BULB. You will then be using exposure durations as programmed into the camera.
HTH

Thanks! Where do I disable bulb? In the Ekos configuration of the camera? Because I did disable it there and set it to 1/4000 but I still got a 1 sec preview. Or do I need to disable it somewhere else? The camera itself doesn’t have a bulb setting, only M (for Manual).

Indi Control panel.
It's an enable/disable toggle under 'options' on the dslr tab.
Leave the 700d on BULB with the dial at M.
HTH

Actually, the log indicates that the correct exposures are taken. I just verified this with my 600D. I took 1/4000 and I can hear the shutter going pretty fast. However, when I use exiftoosl or exiv2 to examine the metadata, the exposure time is always 1 second! Not sure if there is some metadata issue here, but it's definitely wrong. When I take the same exposure from the camera, it's the same speed, but metadata is correct.

This only affect CR2 files, the FITS files generated by INDI show correct time.

Thanks Jasem for the quick check. Like I wrote, when I select a certain exposure time in the main tab of the DSLR Ekos configuration popup panel then the correct exposure time is used but this only results in one image. When I next go back to the Ekos capture tab I get images with the wrong exposure time, even when I select 0,00025 sec.

However, I need to investigate more. Alacant has given me a few hints what config setting to change so I’ll give that a try. Thanks very much!