Simplified All Sky Camera

[Gina]

I'm looking into something a lot simpler than my "All Singing" ASC. 

[Gina]

 

This was an earlier ASC version mounted on the south side of the observatory roll-off-roof that worked fairly well until a vicious storm ripped it off the roof and I found bits strewn over the roof and on the ground around.  I'm thinking of something similar but on the north side of the roof where access is much easier.

 

The camera cooling used a Peltier TEC and air cooled finned heatsink and worked pretty well.  Water cooling is unnecessary.

 

In this version the control board was mounted inside the roof but later versions have all used an RPi single board computer mounted inside the casing and using WiFi to send images to indoors.  This reduces the number of connections through the case to two for power.

Edited August 31, 2021 by Gina

[Gina]

I've done a bit on the latest ASC design but this project is very much a Work In Progress. 

 

I have a quandary.   I like the idea of using a proprietary waterproof ABS box with its seal but can't find one of a suitable size.  They are too deep and the lens would only protrude a mm or so above the lid.  That usual dome would put the centre of curvature well above the top of the lens leading to distortion and possible reduced view.

 

The alternative is 3D printed which doesn't suffer from any such restrictions but is more difficult to seal.

Edited August 31, 2021 by Gina

[Gina]

These photos show the use of an ABS waterproof box and lid with large heatsink for cooling.

 

Heatsink fastened to box.

 

Inside box.

 

Peltier TEC on heatsink.

 

Camera and lens on top.

 

Amount of lens showing above lid.

 

Standard dome with curvature starting well above flange.

[TerryMcK]

Following with interest.

[Gina]

The problem is that for minimum distortion from the dome the lens top has to be at the centre of curvature.  As required, the dome has a hemisphere of clear plastic but the centre of the hemisphere is well above the flange.

[Gina]

The lens does protrude a bit above the top of the lid so it may be possible to cut a hole in the lid of 44.73mm radius (plus a bit for tolerance) to let the dome through from underneath.  Then 3D print a ring etc. to fasten the dome to the underside of the lid.

 

Oh what fun!!!

[Gina]

Hole cut in lid with trepanning tool.  Dome fits in hole nicely.

[Gina]

Now to calculate the height of the spacer. 

• Base to centre of hemisphere is 18.75mm
• Thickness of flange - 1.5mm
• Thickness of lid - 3mm
• Height of lens above lid - 2mm
• I think that's 18.75-1.5-3-2 = 12.25mm

[Gina]

Done some CAD.

Normal view without dome.

 

Section view with case parts shown clear.  Again, no dome.

 

Section view with dome.

 

None of these shows the spacer ring for the dome , dew heater, thermal insulation or any of the electronics.

[Gina]

To seal the dome to the lid I'm planning to use an O-ring clamped to the dome and lid by the dome spacer ring.

[Gina]

O-ring on dome and positioned against the underside of the lid where it will be clamped by a 3D printed ring  as described above.

[Carastro]

Great project Gina.

 

Carole 

[Gina]

Dome spacer and O-ring clamp.

[Gina]

Dome clamp ring added (Yellow Clear).  This holds the dome in place using the flange.  (Matching screw holes in the lid not shown).

[Gina]

A few more photos showing the completed dome fixing.

 

This shows the layers.  Grey is the lid, black O-ring, green spacer, clear dome flange and finally, the clamping ring with screw

 

Top view.

 

Side view showing the lens projecting above the lid..

[MarkAR]

Good work Gina, looks very professional.

[Gina]

On reading some of the information on my earlier ASCs I see I found the NoFan cooler more efficient than the large aluminium finned cooler by Artic.

[Gina]

Bought a new identical box so that I could start again with the hole for the cooler.  Cut the smaller hole for the NoFan cooling pad and drilled holes for the mounting screws. 

 

Here are some photos.  The wide angle lens of my phone camera has caused some image distortion, unfortunately.  Teh box is rectangular and the NoFan circular, of course!

 

 

 

 

 

[Gina]

I have decided on a different approach to the mounting of my newest ASC.  I was going to attach it to the apex of the obsy roof but to do that I would need a step ladder to reach it. Whereas if I use a pipe as I often have in the past, I can attach it to the top of the pipe and then attach the pipe to the obsy.  Better from the safety POV!

[Gina]

Bracket.

(Drat pic won't post.)

Edited December 18, 2021 by Gina

[Gina]

To simplify the process of setting up the firmware in a Raspberry Pi board I plan to use the Astroberry Server which is the OS and all the astro code to get image capture with KStars/Ekos remotely.

 

This is already to run and set up from a browser - no more copy and paste into command line in Terminal.  It's actually simpler than the ASCOM system.

 

Also, Astroberry Server doesn't need the top notch Raspberry Pi board, it will run on an RPi Zero, a small and low cost SBC.

Edited December 24, 2021 by Gina

[Gina]

This is the procedure:-
1. Download Astroberry Server from the web site as a .zip file.
2. Insert micro SD card in computer card reader
3. Run balenaEtcher
4. Choose the downloaded .zip file
5. Choose the SD card
6. Authenticate (run as superuser) and flash the card.  Takes a while but shows progress and validates written image.

[Gina]

This is all detailed in the Astroberry Server Wiki at :-
https://www.astroberry.io/docs/index.php?title=Astroberry_Server#Quick_Start

 

However, IMO this makes it all look much more complicated than need be - hence why I have posted the simplified version.

 

Although recommended, it isn't really necessary to test the download for accuracy - just do this if you have trouble getting it to work.  My experience is that downloads rarely fail these days.

Edited December 24, 2021 by Gina

[Gina]

Internal parts secured.

Edited December 26, 2021 by Gina