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Gina

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Blog Comments posted by Gina


  1. I had a chance today to talk to another member of the group I'm giving a talk to and she pointed out that most of the group are far from technical and all most will know about photography is to point their mobile phone or camera at what they see and press the trigger.  Cameras these days tend to be totally automatic so exposure or aperture mean nothing.  I think I may have talked myself into a "black hole"!  Also, it seems 40 minutes would be a better length of talk - well, that's good anyway! 😀

    So... cut out the technical stuff and just fill the talk with lots of pictures.  Any technical issues can always be discussed in the Q&A session after the talk.  Even things like field of view in degree was considered too technical.  This is pretty restricting - seems I need to rethink my whole talk.  At least I have a few months in which to do it.  Fortunately, I do have plenty of photos of my imaging rigs and observatory which was considered well worth having a substantial section for since I built it myself.


  2. Installing the main control software on the Client computer

    This is KStars and includes Ekos which connects to the INDI drivers in the remote RPi via LAN.  Go to the KStars web page for instructions.  For Linux there in Synaptic Package Manager from the Administration menu.  Search for "kstars" to select for installation.

    Once KStars has been installed, run it from the Education menu and choose Tools > Ekos

    More to follow...


  3. Installing the Operating System and Astro software

    The Raspberry Pi uses a micro SD card as its main drive and this behaves the same as the hard drive on a computer except that this card can be removed and data read from it or written to it.  In fact the way the operating system is installed on it requires it to be out of the RPi.  This tutorial will describe how the operating system is written to the card, the system set up with computer name, user name and password and then further software installed to permit remote control via LAN and the astro software to capture images and control the hardware such as filter wheel and mount.  You need an SD card reader attached to your main computer.

    First job is to download the operating system on the main computer and write it to the micro SD card. Go to the Ubuntu MATE download page,  choose the Raspberry Pi version of Ubuntu MATE 16.04 (takes two clicks) and download it.  The later version (18.04) was found not to work properly.

    5a14839f05cfe_UbuntuMate01.thumb.png.625b9d7935e943aab42934f1cbf9589f.png

     

    Next is to unzip it and write the image to the micro SD card.  In Windows this can be done with Win32 Disk Imager.  For Linux I recommend Etcher which works well (my main PC uses Linux Mint).  Etcher unpacks and writes the OS to the card in one go.  Plug card into reader (with adapter if required), run Etcher and select the micro SD card - careful here not to select you HD or other device.  Also select the downloaded file.  Set Etcher going and a few minutes later the OS is written to the card.  With Windows, install Win32 Disk Imager, unzip the downloaded file and chose the image file (.img) and SD card in Imager and follow the onscreen instructions to write the OS to the card.

    There is a script that has been written for installing the INDI drivers onto the card in the RPi that covers what we are trying to do.  This is AstroPi3 and pretty much does it all.  The instructions given repeat what I have written above.  The lines of code can be copied and pasted from the web page into a Terminal window on the RPi.  Applications > System Tools > MATE Terminal.  Use Firefox on the RPi to go to the AstroPi3 page and copy/paste each command line to the Terminal window.  Hint, 3 clicks selects the whole line for copying.

    The script installs INDI and a few other items of astro software but you don't have to accept it all if you don't want it.  The script may be edited to comment out unwanted items but you need to be careful and know what you're doing though "it's not rocket science" :D  It also turns on SSH so that further command lines can be added from the main PC through its Terminal window and SSH.  At this time the human interfaces can be disconnected from the RPi.

    With this script you end up with a usable system that will capture images and control most of the astro equipment on the market.  Controlling DIY equipment is another matter and one I've worked on successfully - this will be another Tutorial.  The script takes an hour or more to run and has a few y/n responses needed.

    We now should have a working system on the RPi.  Next to install and use the software for the main computer indoors (or maybe warm room).


  4. I'm considering combining the altered version of this tutorial with my earlier one where I included the hardware for remote focussing and controlling a dew heater.  Alternatively, I could write two separate tutorials - one with just the AstroPi3 for all the standard INDI drivers and the other for adding a DIY focuser involving the Astroberry DIY github project and details for adding dew heater and possibly other controls.

    • Like 1

  5. I have just run through this procedure to install Ubuntu Mate and INDI drivers to a new micro SD card for my widefield imaging system.  I have followed the instructions on the AstroPi3 and Astroberry DIY sites on github precisely with no errors.  Radek has updated his Astroberry DIY code since my earlier go at this and has removed the drivers that were causing problems.  In view of this I shall write a new Tutorial to replace this one. 

    All that remains to get my widefield rig working is to check my stepper driver connections against Radek's and adjust if required.  If/when the connections match I expect to use Radek's Astroberry Focuser driver with KStars/Ekos for auto-focussing.


  6. Useful point from Skipper Billy - one arc second is a tangerine at 3 miles.  But since tangerines vary in size maybe a tennis ball at 3 miles - roughly.  This can be in a part that describes the relative sizes of objects in arc - degrees, minutes and seconds of arc.  And something not actually in my list - guiding, which comes under pointing the telescope.


  7. Here is a list of sections I'm thinking of including.  The order may change and I've probably forgotten something.

    1. Introduction
    2. Photography Terms
    3. The problem of earth rotation
    4. Types of telescope/lenses
    5. Types of mounting - tripods, piers
    6. Types of mounts - pointing the telescope/lens at the object
    7. Observatories
    8. Objects to capture - moon, planets, galaxies, nebulae, star clusters, sun (white and Ha/K)
    9. Types of astro camera
    10. Filters - LRGB and narrow band - false colour (HST pallet)
    11. Image processing

    My main problem is not knowing how long each section will take.  Some could be quite short - I don't want to overload my audience with too much detail - this is a general audience, many with no technical knowledge.  Probably a lot of people take photographs but I doubt many know how a camera works.  I'm looking at an overall time of between and hour and an hour and a half.

    I'm thinking on concentrating on the sort of astrophotography I do myself which is mainly DSO, with nebulae uppermost.  I think to cover the whole subject would take a lot longer than 1½ hours.


  8. With lots of problems with the firmware for my all sky camera I decided to take an already corrupted micro SD card and install a new system on it.  Downloaded the latest Ubuntu Mate (18-04-02 beta) and installed it using the latest version of Etcher.  After editing config.sys according to AstroPi3, put the card in the RPi connected to monitor, keyboard and trackball and ran Mate.  After the initial setup I set up WiFi which was simply a matter of entering the password and connecting.  Went onto github with Firefox, read the AstroPi3 script (on RPi this time) and followed the instructions.  All went well until I tried tried to run the script when I got an error message "dpkg locked" and to wait or stop the app that was running.  Waited over an hour but still the same.  Ran the System Monitor and there was nothing running except itself.  At this point I'm stumped.


  9. On 13/03/2019 at 22:25, Skipper Billy said:

    Hello Gina

    I did a presentation to a Scottish Photographic Society a couple of weeks ago - Powerpoint based. Its attached - feel free to bin it, rip it shreds, do anything you want with it. I dont get prissy about copyright of my images etc - feel free to use any images you might want etc etc. All the astroimages are mine and the none astro ones are all copyright free.

    @Skipper Billy  WOW!  That is a very comprehensive presentation :thumbsup:  I have a long way to go to get anywhere near that standard.  OTOH it has given me a lot of ideas - thank you very much.


  10. Photography Terms.

    Before going on to astro-photography I think I should explain a few photographic terms for those of you who don't take photos.  Those who do please bear with me.

    Firstly, image or photo are used interchangeably.

    (Diagram of a camera.)  The main thing you will notice about a camera are that there are two parts - the lens and the body.  At the back of the body is what is called an image sensor.  It used to be film but nowadays it's an array of light sensitive elements called pixels of which there are thousands.  Light coming in through the lens is focused onto the sensor to form an image or picture.  The image collected by the sensor is converted to data which is then stored on a card.  The card may be plugged into a computer to see the picture using software.

    Within the lens are two mechanical components that need mentioning.  One is the shutter which determines how for long light is allowed through to the image sensor and the other is called aperture, which determines how much light gets through.  The aperture is often called the iris, like the iris in the eye and preforms the same function.  The time the shutter is open is called the exposure.

    In daytime photography the exposure is very short as the light is very bright also the aperture may also reduced to avoid overloading the image sensor.  When taking photos at night the light is very much less and a longer exposure and a wider aperture is used to collect enough light to form a photo.  Unlike a camera that is generally used during daylight, a telescope does not have an aperture as we always want to catch as much as the available light as possible.


  11. The Stars, Planets, Moon and Sun.

    Everyone knows that the sun and moon appear to move through the sky by day or night.  In the beginning it was believed that the Earth was the centre of the universe and that sun, moon and all the stars rotated about the Earth.  With the exception of Flat Earthers, it's now known that the earth isn't the centre of the universe and nor even is the sun.  Most people now know that the reason everything in the sky appears to traverse the sky from east to west is that it is the Earth that is rotating.  This rotation is a major concern when trying to photograph the night sky or indeed, even observing.

    If you take a photo of the sky with a long enough exposure to show the stars you will get start trails (photo of star trails).  Now whilst this gives an interesting picture in itself, this is now what we really want.  Even with observing there is a problem as a telescope has to be moved to follow the stars. 


  12. Introduction.

    This talk is about Astronomy Photography or more commonly called astro-photography or astro imaging but before going into the main subject I shall describe how I got into it and also a few general principles that govern the whole process.

    I have been interested in astronomy from a young age having been introduced to it by my grandfather.  Over the years I have looked at the night sky with binoculars and indeed, this is a good way to start observing.  Most of my life I haven't had very good night skies for astronomy due to light pollution but when we moved here, away from towns and cities the night sky appeared awesome with thousands of stars visible.  (All sky camera image of night sky with the Milky Way.)  With such skies I felt I had to take more advantage of them than I had to date and bought a relatively cheap telescope from Amazon.  (Picture of the Celestron whatever it's called.)

    I used this to get a more detailed view of the night sky using various eyepieces that allowed various angles of view.  But having been interested and practicing photography since I was a child with a Box Brownie. it was inevitable that I would want to go on to astro-photography.  I started with a webcam but moved on through an ordinary DSLR as used for standard photography to much better and more expensive dedicated astro cameras.

    After a few months I discovered a very active astronomy forum online called Stargazers Lounge, from which I have learnt a lot.

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