All metal AllSky camera with inner AR coating glass dome

[MMysBelec]

After few attempt with plastic / 3D printed cameras with acrylic dome, whose always have few years of live, then dome becomes foggy, and plastic starts degrade due to sunshine, I decided to make more durable version. I started with design of the metal body, and obtained glass dome from BRD optical domes (now Ecoptik) https://www.ecoptik.net/products/optical-dome/
I selected 100mm model, BK7 glass, with visible+IR range anti-reflective coating on the inner surface and 4mm of glass thickness.

Camera is operated in visible+IR mode, for maximization of sensitivity.

Camera consist of cylindrical aluminum body, with top and bottom parts sealed by the rubber O-rings. Top part consist of plate with circular groove, where the heating element is placed, and glass dome is contacted and glued - sealed to it. There are two ports into this airtight space, one for pre-focused camera+lens assembly, and one for removable desiccant chamber. Both parts are sealed by rubber rings too.

the bottom plate has two IP68 water-tight connectors. One for Ethernet, and second one for 12V power or 12V backup battery if powered using POE.

The RPi is connected together with self-designed hat, which contains POE module, making 12V for heating from 48V POE, also step down for RPi, and temperature/humidity sensors and heating control. Both boards are mounted using spacers and cold-finger which is contacted between CPU and cylindrical body of the camera using thermal paste. This removes heat from Rpi very efficiently without any fan, even in summer on direct sunshine.

There is also possible to use this camera housing without RPi, together with PC. In this case, there is USB3 water-tight connector on the bottom and Arduino micro is populated into board, and manage heating in autonomous way.

There is enough space inside, for example for using external USB3 SSD disk and backup battery inside. But I prefer backup battery inside of building, because of less thermal stress. Final assembly looks like this:

Lens used is an approx. 100 USD chinese IR corrected lens, suitable for 5Mpix image, with focal length 1.45mm, f/2, with image circle almost the same as the sensor height. So final image is only slightly cropped. The resulting image looks like that, at the clear night:

Next image shows the quite small amount of reflexes, when outdoor light on the terrace shines over all 30sec. long exposure directly into camera. Glass + AR coating is doing good job. This was strange with acryclic dome.

[MMysBelec]

I also tried colour version of ASI 178, this shot is with moon on the sky:

But the sensitivity of mono including IR range is much better.

[EricClaeys]

Wow, this looks really nice. Are you going to make them available for others to purchase?

You must have access to a lot of equipment to make all your parts and circuit boards.

Does the glass dome provide better results? How did you decide what size to get?

Eric

[halohms]

It's here at the top of this thread. https://www.ecoptik.net/products/optical-dome/

[MMysBelec]

This is a quite a long time, I purchased 10 pcs. and for such batch, one was around 150 USD if I remember correctly. Because of company name change (former BRD Optical) and total web structure change, I´m unable to locate exact type. The domes are renamed. But it was stock type, not custom made. ECO-D-100B looks like the type I have. For purchasing, I wrote direct e-mail to the company.

[caphector]

I'd tried to find a similar dome but was quoted a lot more than that. This is an excellent reference and I will need to get one!

[EricClaeys]

I just ordered two 100mm x 4mm thick domes for $270 each. I really wanted domes with a flange but they were $930 each, or 10 for $400 each. I was tempted to get 10 and resell them.

[MMysBelec]

I understand so with flange the mounting is easier, but the flange is not needed. You can make any metal part - base of the dome, of shape you wish, maybe with holes for mounting, with hole for lens etc, similar as I have. Then simply glue the dome to it. After few attempts of finding suitable glue, I ended with Loctite 3106 UV curing glue, which has perfect adhesion to both metal and glass. Simply make an grove into material of the base (stainless steel, alluminium), about 4-5mm deep, place some glue into it, and insert the dome. Then move the assembly to direct sunshine (or under UV lamp) and it will harden. Be careful, you have one attempt only, There is almost no way to remove the dome later without damage. Also, when handling, do not put fingers onto inner surface with AR coating. The best way is to prepare the base, apply glue, and then unpack the dome form its vacuum bag, and immediately glue it to prepared rest of assembly, because the dome is perfectly cleaned in factory before packing. If you contaminate the inner surface by anything, there is quite hard to clean it perfectly again.

[quidnonn]

WOW!
That is one SWEET set up you designed and great pics!
Looking at thr cmaera settings - were you using "autogain" for the 178mm? Looks like 30 sec exposure at gain 255. Can you share a copy of you settings page? I'm courious as to the Brightness and threshhold setting - Thanks!!

[MMysBelec]

No, I´m using automatic exposure with limit of 30sec. max and manual gain 255 for night. There should be better to use fixed exposure 30sec. for having no gaps in exposures, and adapt gain at dusk/dawn. But auto-gain does not work correctly with ZWO. See this:

#3244

[MMysBelec]

Yesterday night, first bright bolide, with explosions.

[EricClaeys]

@MMysBelec, Martin, did you get a dome with a flange, or without?
The 100mm wide, 4mm thick dome is $270 and the one with a flange is $930 . A huge difference.

[MMysBelec]

I used type without flange.

[EricClaeys]

@MMysBelec, Thanks for that info.
How did you pay Ecoptik? None of my banks do an international wire transfer.

[MMysBelec]

I paid normally by bank transfer. What kind of bank is that? Every bank can do that, at least in the Czech Republic. I've never met one that couldn't.