Gina

I had plenty of wet weather when I built my observatory. Bought an enormous tarpaulin to cover it - roof and all 4 sides!

Regarding camera thermal insulation, I thought I had closed cell polyether foam but it turns out to be open cell. However, I have plenty of polystyrene foam blocks that I could carve up for camera insulation. That is a very good thermal insulator. But the easiest form of insulation would be 3D printed where I only have to design the shape in CAD software and print it. This would be self-supporting and easily attached to other parts whereas polystyrene would need enclosing to hold it in place. With 3D printing I can use honeycomb infill with solid layer every few layers to form closed cells. The camera thermal insulation would almost fill the space in the outer casing below the lens leaving the air in the dome. I'm thinking I might go back to my previous idea of drying the air in the whole ASC casing with silica gel bags and hermetically sealing the outer casing. This would be easier if the RPi were also in the outer casing as then just two connections need pierce the sealed enclosure. Heat from the RPi would aid dew heating that I think a dew heater would still be needed to stop dew on the outside of the dome. Since this will be a nighttime only ASC, the RPi would not be powered in daytime and overheating would not be a problem.

Haven't decided yet but previously I have used 6 x 6Ω which is 36Ω giving 5.3W from 13.8V or 0.7W from 5v.

Watching with interest.

I can thoroughly recommend the Duet control board. OK a tad expensive but IMO well worth it. Very reliable and no editing and recompiling of firmware, everything is controlled from any web browser (I use Firefox). All firmware files can be edited from the browser and even files uploaded to the Duet. Also, printing parameters can be varied while the print is running.

I've been looking into various ways of sealing the camera to keep damp out so that I can cool it well below freezing and also maybe include some desiccant to dry any air already inside. The cooling tests have shown that even without sealing and desiccating, no wet gets onto the circuit board or upper part of the inside of the casing. All the damp/wet is in the bottom away from the electronics. I guess this is because the bottom is colder than the rest and any condensation prefers the colder parts. This makes me wonder if I'm over-thinking the situation.

I don't have that problem. I have Duet WiFi control board which doesn't rely on a computer to keep going - only for setting up. Plus I use Linux rather than Windows. I thought you used Linux, James?

I'm sure it would be. I'm always interested on observatory builds and improvements and I know others here are as well.

Not the usual postman but Parcel Force - a top grade Peltier TEC from RS-online for my All Sky Camera. On testing this will drop the temperature of the non-cooled astro camera a whopping 30°C.

Good luck Louise 😀 We will be watching your progress with interest and support if you need it.

I did a test for focus shift from the dome using the ceiling light fitting to focus on. The difference seemed to be about 10° clockwise rotation of the focus ring from no dome to dome but I shall do a more accurate measurement on the moon if/when we get some clear night sky. There's rain forecast for all night tonight. I reckon there's a reasonable chance of using preset focus, avoiding focus motor and gears etc.

I was interested in radio from a very young age, encouraged by my father - my first receiver was a crystal set! Later I went on to valves and transistors... I was in the Radio Society at university. Never got to getting a transmitting license though even though I did know a bit of Morse code. Any transmitting I did was very limited range so as not to contravene the regs.

That should have printed much better then!!

The camera casing was wet when I touched it so better thermal insulation is possible. The plan is to have a moisture barrier around the camera and Peltier TEC including the USB plug with a small amount of room for desiccant. Outside that would be thermal insulation - there's plenty of room for that. I have plenty of closed cell polyurethane foam. I also have kitchen foil (shiny aluminium foil) if that would help.

I've gone down to -20°C in the past with water cooling on the TEC hot side but with sealed camera chamber and desiccant. I'm planning the same dry environment for the camera in this latest version. At least damp condenses on the case rather than the electronics but I still don't want to risk it.

Camera is still working fine at -3°C and still slowly getting colder. The condensation doesn't seem to be affecting it.

Dropped below freezing now and at -1.5°C. Still slowly getting colder.

Put the camera cover on and it's getting colder - now down to 2°C.

Temperature has come down another half degree and 20m in. Ambient temperature is 19.5°C. So running the camera with no cooling raises the temperature by 8°C and the cooling decreases the camera temperature by 21°C in the present test conditions. Oooops!! Just noticed I didn't have the camera thermal jacket on - camera covered in condensation!!

New RS Peltier TEC has arrived and I've set it up to cool the camera using the 80mm fan and Artic passive cooler as before. Time 14:15 - Starting temperature 27.5°C - TEC supply 13.8v and drawing 3A. Time 14:20 - Temperature 7.5°C - TEC supply drawing 2.8A. Time 14:25 - Temperature 6.5°C - TEC supply drawing 2.8A. Seems to have settled after just 10m. That's a drop of 21°C. Temperature has come down fast! What a difference from the cheapo TEC1 12703!!

How big was the cat print? If it was a couple of cm (miniature) that may not be too bad though my little test prints of cats I did years ago were better than that and I thought 3D printers had advanced a lot since then (mine certainly have).

Ah! Didn't realise it cost that much, something gave me the impression of more like 150-200!

Yes, that is certainly one way to do it. The moon (if available) is certainly a good object to focus on. I would assume you are using the Fujinon lens and it's screw thread for focussing. Have to say, I found that very coarse and rather difficult to cope with. The lens I'm using now has its own focussing ring which is silky smooth and not loose.

I certainly haven't had that with mine! OTOH I'm not sure what the light source is.