The image you can see here AllSkEye Live is the result of a ‘small’ project I started in early 2019. Here is some info and background:
I live in a major City with very high levels of light pollution. When I setup my all sky camera I can only see the very brightest stars and planets (and the moon). It can also get very hot and humid and the sun is very aggressive, probably not the best for a permanent all sky camera. This was a bit of a problem when developing new features for the AllSkEye software as it really needs a permanent setup to properly test everything.
So for a while I’ve looked at various options of remotely hosting an all sky camera in a better location. What I needed was a dark location with good weather and fast internet. A remote telescope hosting site was really the obvious choice and I decided to write a short email to the e-Eye remote hosting facility in Spain. They could not have been any more helpful and were really excited about the project! So that was the location set, I just had to come up with the hardware.
After I got some feedback from e-Eye about the location and surroundings it became clear that the setup needed to be split into two parts:
- Camera housing: Camera, remote focus mechanism, dome heater and cooling/de-misting fan
- Inside control box: PC, USB switch, power relay box, 12V transformer, network switch
I already had the following parts from other projects so decided to reuse the here:
- ASI ZWO 178MC
- Intel NUC Computer
- Fujinon 1.8mm f/1.8 Fisheye lens (HF1.8HB-L1)
Connecting the two I needed to install:
- 5m USB2 cable to connect camera
- 9 core cable to supply and switch the focus motor, the fan and the dome heater (all 12V)
To be able to prototype and create the housing I finally had to bite the bullet and buy a 3D printer… I decided to go for a Creality CR10s Pro which was reasonably priced (even including all the upgrades and small fixes it needed to become a decent printer ?) and had a large enough print area. After brushing up on (the excellent and free) Fusion 360 I created the following concept:
- A solid main body which can be permanently attached to the mounting point
- A dome with compression ‘ring/lid’ to push the dome onto a rubber gasket and provide a waterproof seal. A lip on the top of the main body slightly raised into the dome provides additional protection should any water seep through.
- A removable assembly which ‘hangs’ inside the main body and contains all internal parts (camera, lens, heater, focus mechanism, fan, connectors). This can be easily slid out from the main body for maintenance by turning the assembly until the support beams reach a gap in the support ring. It also has three adjustment screws which can be used to level and adjust the height of the assembly inside the main body.
- A bottom lid which acts as protection from underneath and shields the connectors from the elements. It’s also used to fix the hanging assembly in place.
After a lot of trial and error, test prints and changes this was the final result:
As I’m not really setup to print ABS so I decided to print all parts open to the elements in PETG. This should hopefully provide good protection from the elements as well as sunlight. All internal parts were printed in PLA.
I initially was going to use a spare Starlight Xpress Oculus dome for the setup however pretty much last minute I decided to replace it with a real glass (BK7) dome from Knight Optical in the UK. That was an expensive decision but I think it was worth it. Especially under bright conditions (e.g. moonlight) the glass dome has much less scatter compared to the Perspex dome. I was also hoping it would last longer and stay cleaner but only time will tell. I did treat it with a nano coating so rain would pearl off easily, hopefully that will help as well. Funny enough (or as expected) it doesn’t rain often, which is obviously great but I think is a bit of a disadvantage in terms of keeping it clean.
One small challenge in changing to the glass dome was that the dome does not come with a lip i.e. it’s a perfect half sphere. So I had to modify the clamping ring to very exact measurements (slightly smaller than the dome diameter) to ensure that the ring would push the dome onto the gasket without the dome slipping out at the top. I also didn’t want it too high as not to loose the 180 degree visibility.
Lens and Camera Assembly / Heater / Focus Mechanism
In the final design the camera is screwed into a bottom assembly plate which also encloses the camera with four pillars. On top of these pillars sits the heating element holder. The lens is loosely screwed into the camera end thread which allows the focus motor to move it.
The camera (ASI 178MC) and lens (Fujinon 1.8mm f/1.8 Fisheye) combination produces a good field of view. It doesn’t quite give a full 180-degree circle but uses the available sensor area pretty well (and leaves some space for the text and logo overlay).
Heating / Cooling / De-Misting
The heating element was purchased from www.dewcontrol.com. Having a heating circle seems like a good idea as the heat is dissipated evenly to the dome. I wanted to get the heating element as close as possible, preferably into the dome but discovered that the Fujinon lens was just a little bit too big and it wouldn’t slide over it. So I had to come up with a heating element holder to position the heater in between the camera and the lens. As the dome is fairly small I think this will work well and also ensure that the lens is warmed as well.
I wasn’t sure whether I needed any cooling or de-misting mechanism but to be on the safe side I decided to install a small 12V PC fan in any case. The fan draws air from the bottom of the housing and blows it through a small duct past the heating element towards the dome. The housing has small ventilation holes at the very top which will hopefully allow some of the air to escape and produce a small airflow through the dome.
I was really in two minds whether to include a remote focus mechanism or not i.e. functionality vs. complexity. With hindsight both came true… It is super convenient to focus the lens and works really well but unfortunately it also seems to have a slight problem in that very occasionally it seems to drift just a tiny bit and needs refocusing. It didn’t do that during testing… Anyhow, I’m sure I will get to the bottom of it eventually, certainly on my next visit to e-Eye ?
The focus mechanism consists of two 3D printed gears, one around the lend shaft, the other on a vertical DC motor shaft. There is also a small spring mechanism to push the gears together and prevent the lens from being too loose. This introduces a slight bit of tilt which isn’t very noticeable though. The control mechanism is a very simple turn this way, turn the other way mechanism by changing the polarity of the 12V supply.
On the camera side there are two waterproof connectors:
- 9 Core Cable
To further protect the connectors from the elements and to prevent bug ingress through the ventilation slits I also added a mesh and bottom lid:
For my control box I reused an old PC housing which I still had kicking around, probably from the last century… Here I needed to find space for:
- The Intel NUC PC
- A 12V Power supply
- A 12V to 19V converter to supply the NUC with 19V
- A relay control box to do all the switching (heater, fan ,focus, reset NUC, reset network switch) – for this I selected a Lunatico Dragonfly controller
- A network switch to distribute the LAN network
- A USB switch to allow physical on/off switching of the USB cable to the camera (to reset the camera should it lock up)
- USB hub to connect cameras
- Ethernet port to connect LAN
- 9 core cable connector for camera housing supply and switching
- 220V Power supply
This was the final layout:
I also decided to add a small UPS which supplies the power for the control box and gives around 5 to 10 minutes of operation. It’s also linked to the NUC via a USB cable and will trigger a shutdown if the battery runs out.
The Dragonfly control box was a bit of a ‘luxury item’ as I could have done the same with a much cheaper USB or UDP relay board (eventually I think I will swap the Dragonfly out and put it to better use, hopefully for my own remote scope setup ?). It is very convenient though as you can reach it directly from anywhere with an internet connection which is of great help if there are issues with the other components (PC, IP Switch, etc.). Already I’ve used it a couple of times to reboot the PC after some dubious Windows updates where the PC would not respond to Teamviewer anymore.
The Dragonfly is also becoming much smarter with every update. You can run internal scripts as well as internal macros which are ideal for watcher functions such as reboot the switch or PC if no internet connection for x seconds and such like. Clever piece of kit!
PC / Software
The PC is a small form factor Intel NUC i5 machine which is more than capable of running the whole setup and has plenty of connectivity to make everything work. On the USB side I also included a Yepkit USB switchable hub which basically allows you to remotely switch a USB connection as if you had physically unplugged the cable. I though this might come in useful if the camera/USB connection locks up which mostly requires unplugging of the device. In practice I’ve not ever actually needed it so far which I guess is a good thing! Better safe than sorry. For PC remote control I am using Teamviewer which seems to work pretty well and is reasonably fast (as well as free!).
The camera is of course run by the latest preview build of AllSkEye ?! Luckily the internet connection is fast, so uploading the latest images to my, as well as the e-Eye website via ftp is no problem at all. All other files are kept locally at the moment but I do have plans to export original fits files for further processing and archiving at some point.
AllSkEye is also controlling the fan and heater inside the camera. This is done via the AllSkEye trigger mechanism and scripts that are called when certain conditions occur. At the time of writing only the cooling fan is seeing some action. It’s pretty hot during the day and with the greenhouse effect the camera sometimes reaches close to 60 degrees C… Once the winter and/or bad weather arrives I will need to find good trigger points in temperature and humidity to hopefully keep the camera dome dew and frost free. Time will tell!
Location / Installation
I was really happy that I got such a positive response from Jose Luis at the e-Eye remote hosting facility in Extremadura, Spain (https://www.entreencinasyestrellas.es/en/en-home/).
The location is perfect for my needs with low light pollution, clear skies and a fast, fiberoptic connected internet connection. It’s also pretty easy to get to from Europe, which was another consideration as I wanted to go there personally to install it.
After all the preparations were completed, I booked a little ‘holiday’ directly at the e-Eye facility. They do have some fantastic facilities with really nice Bungalows, a swimming pool and beautiful surroundings so I decided to stay for three nights to relax!
Once I got there, the team was extremely helpful in getting me up and running and we manage to fix the housing to the control room roof of the new remote hosting complex in no time. The control box was stationed inside the control room and from there it was pretty much plug and play.
After some fiddling with settings and focus the results were really amazing (compared to what I managed to produce before):
Here is a sample video of an entire night:
I’ve also managed to capture a few nice meteors since. Here is a big one: