Gina

There isn't really any more I can do to the ASC until I get the 1.55mm lens (or possibly a replacement Fujinon 1.4mm though that's no longer the preferred option), so I've put all the parts in an empty box, labelled it and put it to one side. I need a rest from it anyway!

Oh I don't intend to give in though I might have to cut back just a little.

Maybe I should stick to doing things with my hands, though they're not as good as they were. I do seem to be having a problem just lately in getting my brain round the more complicated things. I'm getting worried that my age is catching up with me and now I'm being serious. I tend to make fun of these things and not take myself too seriously but I'm definitely not as clear headed as I was.

The only thing I seem to be having much joy with lately is arts and crafts - paper craft particularly! At W.I. Thursday evening we had a craft session making beads and hence bracelets or necklaces from rolled up bits of coloured paper and PVA glue. I made a necklace and won first place in the competition. I was flabbergasted.

Having printed enough parts to hold the camera, TEC and waterblock together, I set up to see how cold I could get the camera with the thermal insulation and all thermal parts in good contact with thermal grease (just light pressure). More trouble - no Peltier TEC current and no cooling Took it all apart again and checked volts across TEC - power was getting that far but no current. All I can think of is that an internal connection or one of the elements has gone open-circuit.

I have applied for return of that Fujinon 1.4mm lens and have ordered the 1.55mm lens from Bern at Modern Astronomy. Several parts printed successfully.

That might be alright if only I could get the dimensions right...

The more I think about it the more I like the idea of the 1.55mm f2 lens from Bern. It seems to give excellent resolution and no oblong stars. It's also smaller than the Fujinon making for a smaller overall rig.

Currently continuing to print parts for the ASC. I'll give lenses more thought over the weekend but I think I shall have to send that faulty Fujinon back.

It's 1/1.8" ASI 178MM at present 178MC in future - 5.992mm image height. In view of the trees and rising ground to the NW I don't need views down to the horizontal all the way round. The Fujinon 1.4mm lens gives 185 degrees and the full image circle is covered by the 178 camera sensor. This covers not only the sky but some of the ground around too (quite nice in daytime). I would prefer to buy from Bern at Modern Astronomy as I've bought there many times before and the service is excellent. The lens is a pound cheaper than Dew Control too.

Interesting thought - thank you. Yes, explaining daytime photography then going on to astronomical photography is definitely better.

The Dew Control 1.55mm All Sky Camera Lens looks very similar to the Arecont version and also Modern Astronomy seem to sell a similar one at a similar price. I reckon that would give me sufficient coverage if I can't get any joy with the Fujinon lens and the fact that it has a focus facility is a bonus.

I suppose I could wait and see what it's like with the colour version of the camera (ASI 178MC) which is on order. The dome might make a slight difference. I've been trying to think if there is anything that could cause the elongated stars other than a faulty lens.

This ASC seems jinxed ? Maybe I should turn my attention to something else for a while...

Yes, it's 1.4mm according to the label and it gives the full sky view. So yes, certainly seems the right one.

I guess there a vanishingly small possibility that distortion in the dome corrected the distortion in the lens... No, not so, I tried the lens without dome and it was perfect. I feel gutted! I don't know why the mast fell and it was sheer bad luck that the lens caught the corner of a paving stone. Guess I shall just have to put up with less than perfection! I guess I could ask for a replacement lens but there's no guarantee that another will be any better and could be worse.

No the lens is uncovered. The colour image was taken with the old lens and ASI 185MC camera last August with the 3" acrylic dome on. That was before a severe storm ripped it off the observatory roof.

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.