Gina

Not too bad - some star elongation near the edge. I get the impression that this lens is not as good as the first one but I could be wrong. I'll have to check previous images.

7°C other settings the same. Cropped image. Same image adjusted in GIMP with Curves.

20s exposure - gain 300 - gamma 40 - temperature 12°C. 20s exposure - gain 200 - gamma 50 = temperature 10°C.

Clear sky tonight but I've been out to WI and just got back. Not quite ready for testing the water cooling outdoors as I still need to print some casing parts but I can put the camera and lens out out the mast (as long as I'm very careful). No clear night skies forecast for at least a week after tonight!

Yes, that's what I'm thinking of for high speed imaging such as Ha solar or planetary. The RPi is fine for DSO imaging and the all sky camera.

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.

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.

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.

Done ?

If there's anything with a sharp corner around I'm bound to crash into it sooner or later!

INDI is running on the RPi which is running Linux. I think KStars/Ekos has a Windows version but not sure. I'm using Linux Mint which is very similar to Windows 7 from the user point of view.

I would indeed be very interested Carole, thank you very much.

I broke it! Or to be more precise whilst I was testing, the mast fell down and the top of the lens caught the corner of a concrete paving stone. The top lens element has completely disappeared though I suspect it or the fragments ended up in the pond. I tried feeling around in the bottom of the freezing cold pond for a few minutes but found nothing.

Replacement lens for my all sky camera.

Here it is through an open window. Those aren't starts in the sky, they'r hot pixels. 20s exposure with gain at 0, camera temperature 26C with no cooling.

Been trying to use a fixed focus with the new Fujinon 1.4mm lens. I cut some thin card to put in between the size adapter and the camera body. That wasn't enough so tried two layers which was too much so cut a piece of paper to replace the second card and that seems about right. I can get very fine adjustment by how tight I have the adapter. Here are some photos with the rig pointing out of the window towards the village. Firstly full frame then zoomed right in to the highest magnification in the KStars FITS Viewer. The final image is with the 3" dome over the lens.

I'm thinking of 3D printing the outer casing in PMMA filament (acrylic) so that I can see the state of the bags of colour-changing desiccant beads (orange dry - green wet) without opening the casing. This won't be glass clear but translucent though still showing the colour of what's inside.

I have two clear acrylic domes I could use (more if you count damaged ones). The one I've been using is 3" (75mm) and an ideal size but it has slight damage near the edge on one side. I also have a 4" (100mm) brand new, unused one so the question is whether to put up with some smearing of the image (it could be oriented towards the NW where the trees prevent a horizontal view of the sky) or go for the pristine big one that is a lot bigger than needed. A third alternative would be to buy another 3" dome but that's more money and I've already spent too much! I guess smeary trees are no real problem, as long as the good part covers most of the visible sky, it's good enough.

Unfortunately I'm not an observer so can really only cover imaging but that will be the title of the talk viz. "Astronomy Photography". OTOH, I can certainly touch on observing and how you need a very much bigger telescope to see anything directly.

Mount control is already covered by standard INDI drivers. I do indeed control mounts - I have an NEQ6 and EQ8 both of which I have controlled with INDI drivers from KStras/Ekos indoors, with INDI on the RPi.

The (used) Fujinon 1.4mm lens arrived in the post this morning. It's supposed to be used but looks brand new ? Hooray!! I really didn't want to mess about with the Fujinon zoom lens, I've played about with that in the past and didn't like it. Controlling those little levers was very difficult and never really worked well. I have checked my funds again and realised I had money in a saver account so transferred some of that to my current account and now have sufficient funds for the ASI 178MC camera which I've ordered from FLO. I guess I knew I was going to take that route eventually as I've done nothing towards designing controls for the zoom lens. Only trouble is the camera is not in stock and will take a week or so to arrive. Meanwhile I can use the ASI 178MM and get everything working with that.

I need to be sure the data I'm getting is really what I think it is though the only way to be sure will be to wait for a clear night sky and cool the camera until the noise disappears or until it's as cold as it will go. One thing is certain, I can get to a lower temperature with water cooling than even with a fan blowing air through cooler fins.

I'm getting some anomalous results from viewing the FITS images with KStars. I think it's normalising them - not a lot of variation between +20°C and -4°C. I'll find another FITS viewer.

Temperatures didn't quite wok out as above, turned out to be 20°C, 8°C, 4°C, 0°C and -4°C which was as far down as it would go without lagging the camera casing. I'll post the darks shortly.

Starting at ambient temperature of 20°C with no cooling and then 10°C, 5°C and 0°C - 60s exposures, gain 300, gamma 50. ASI 178MM. Water cooling system but no camera thermal lagging.