DIY all sky camera

[naskies (Dave)]

After having great success with adding an electronic finder (60x40 degree FOV using a 6 mm C mount lens) to my GSO RC8, I decided to assemble my own all sky camera to get a better idea of live sky conditions outside the house/tent.

I ordered a 1.25 mm f/2 185 degree FOV fisheye lens from China. The lens is designed for 1/3" sensors with C mount, which I attached to the QHY using a C-to-T mount adapter ring.

I bought the dome - case only - from Jaycar. I've thrown in a spare dew heater for 1.25" eyepieces, which will hopefully keep the dew off the dome. I'm still waiting to receive a 12V dimmer from eBay which I'll use to regulate the dew heater.

There's a 5 metre USB extension cord attached to the QHY5 which will connect to my imaging laptop inside my observatory tent.

The image quality is very good, but I'll have to wait to test it out on the stars (cloudy here). Unfortunately, I'd assumed that the advertised "185 degree field of view" referred to the diagonal axis (6 mm on 1/3" format) - but it turns out the lens provides the full field of view on the vertical axis (3.6 mm). In hindsight, I should have ordered the 1/2" version of the lens instead.

My todo list:

* Set up automated capture and internet upload (when my observatory is set up at home).

* Replace the QHY5 with an ASI120MC colour camera. I need the QHY5 for wide field autoguiding, plus the ASI has a convenient 1/4" mounting hole at the bottom and USB connector on the side. I think the exposures would be short enough for me to image during the day, and I could use it as a meteor camera (in video mode).

* Use the linear actuators I have left over from a previous project to be able to adjust the camera tilt remotely.

* Upgrade the lens to something faster & higher quality, e.g. the Fujinon 1.4mm f/1.4 lens used by the SBIG ASC.

As an aside, after doing all this I noticed that the QHY5L-II and ASI120MM cameras now ship with the option of a fisheye lens and mounting brackets/tripod by default. Must be getting popular!

PS: if I won the lotto, I'd attach this 220 deg FOV lens to a full-frame DSLR and use that as my all sky camera

[DJT (David)]

Nice one.
Was thinking about doing this with the ASI I picked up, especially given propensity to drop crud on the sensor, as it came with the wide lens in the box. Wasnt sure where to pick up a dome but now I know

Thanks.

[naskies (Dave)]

Cheers David!

Thanks to some clear weather in Brisbane - finally! - and finishing exams, I've finally had the chance to give the ASC a whirl.

The image quality from the lens is very good (see image #1 - image scale is 15 arc min/pixel), but the QHY5 isn't sensitive enough for this lens - I need 15 second exposures at 50% gain, whereas I'd prefer 1 to 5 sec exposures. That Fujinon lens paired with a QHY5II is looking mighty tempting!

I've also attached an image from my electronic finder (a 6 mm C-mount lens on an SBIG ST-i camera) whilst imaging the NGC6334 Cat's Paw in the tail of Scorpius. I selected the focal length so that the centre 8x5 pixels (40x30 arc min) corresponds to my main camera's field of view. This makes centering stars for polar and N-point alignment very, very easy.

[BPO]

Nice project! I'd hoped to build one too, but I just ran out of time, and the cost would have been at least as much as the least expensive commercial model I could find, the Moonglow Technologies All Sky Cam. These do an amazingly good job considering the low price.

One day I'd love to have a crazy high res ASC like those used at the Chilean observatories.

[alistairsam]

nice work David,

could you tell me where you got the C-to-T mount adapter ring?
and can't you use the QHY5 with 100% gain as we normally do for guiding?
it should be sensitive enough with 100%. you could possibly take a dark frame if its too noisy.
also, where did you get the c mount lens for the viewfinder and what focal length is it?
I have the qhy5L-2 and didn't get the 8mm C lens or the fisheye lens.
I was looking more to adapt it to the polar scope of the neq6.

Cheers
Alistair

[trent_julie]

Dave,
I hope you don't mind, but I fed your allsky image into a program I have written. It analyses an image and sets various kinds of alarms when cloudy or clear. The software is named Tektite Skies.

Trent

[marlin34]

This looks great. Good job! I love the stuff you're coming up with. Julie that's freaking amazing!

[naskies (Dave)]

Originally Posted by BPO

Nice project! I'd hoped to build one too, but I just ran out of time, and the cost would have been at least as much as the least expensive commercial model I could find, the Moonglow Technologies All Sky Cam. These do an amazingly good job considering the low price.

Thanks mate! I was actually inspired to get an ASC after seeing the images from yours - especially of the auroras!

One day I'd love to have a crazy high res ASC like those used at the Chilean observatories.

Yep! If/when I have the budget, I'd like to a used full frame DSLR for cheap - Canon 5D or mkII - throw a fisheye lens on it, and just run it continuously until the shutter gives up.

Originally Posted by alistairsam

nice work David,

could you tell me where you got the C-to-T mount adapter ring?

I bought the SBIG adapter as part of a big order, but you can find them on eBay and AliExpress if you search for "c to t adapter" - just watch out for the male/female-ness of it as many of them are for lens-T-to-camera-C (mine was lens-C-to-camera-T).

and can't you use the QHY5 with 100% gain as we normally do for guiding?
it should be sensitive enough with 100%. you could possibly take a dark frame if its too noisy.

The QHY5 defaults to 50% in the ASCOM driver - I never needed to change it in the past while guiding with a 50 mm guide scope. I'll give it a go, thanks.

The little red light on the back of the QHY5 lights up the dome - making dark frames impossible while it's in the dome. I'll have to do some solid taping over it.

I'm actually thinking of using an ASI130 camera instead. Much more sensitive (similar to the QHY5L-II, I think), it has a centre 1/4" screw hole for easier mounting, and the USB connector is on the side - much easier mounting.

also, where did you get the c mount lens for the viewfinder and what focal length is it?

This is the one I ordered:

http://www.aliexpress.com/item/1-25m...857257969.html

Shipping is a bit killer, but it arrives within a couple of days. That same store will also do cheap/free shipping but you have to wait about 3-4 weeks.

There are even cheaper fisheye lenses available there, though I don't think the image quality is quite as good.

I have the qhy5L-2 and didn't get the 8mm C lens or the fisheye lens.
I was looking more to adapt it to the polar scope of the neq6.

Jaycar sell 8 mm rectilinear C-mount lenses:

http://www.jaycar.com.au/productView.asp?ID=QC3317

Otherwise you can find a local surveillance store and see what they have in stock (they tend to call them CCTV lenses).

I actually have an electronic view finder as well as the ASC to control / monitor the set up remotely. In the attached screen shot, you can see the field from my main scope + camera (top-left), which represents a ~ 5x4 pixel or 40x30 arc min rectangle in the middle of my 60x40 degree view finder (bottom-left), and the view finder is a fraction of the ASC's 185 degree FOV.

I was almost in trouble once with the scope pointing low near the horizon in the early morning. The view finder was completely clear - but rain clouds had moved in overhead and covered the entire sky except for the little patch of the view finder

Originally Posted by trent_julie

Dave,
I hope you don't mind, but I fed your allsky image into a program I have written. It analyses an image and sets various kinds of alarms when cloudy or clear. The software is named Tektite Skies.

Trent

Trent, thanks for that. No worries at all. Unfortunately, my current images have a lot of artefacts because I haven't got the dome mounting ideal yet (internal reflections, no dark frames, etc).

Originally Posted by marlin34

This looks great. Good job! I love the stuff you're coming up with. Julie that's freaking amazing!

Thanks mate!

[DJT (David)]

Following on from this thread, I found a use for the ASI120MM. I havnt done a lot of planetary as am still deciding on which way to go with filters, so while its kicking around doing not very much I thought I would have a go at this.

Thanks for the idea, David.

[naskies (Dave)]

Monday's ISS pass was nicely captured on camera (sitting on the grass in the bottom-right corner of the attached photo):

http://www.youtube.com/watch?v=lbS7tYYLQ-Y

Originally Posted by DJT

Following on from this thread, I found a use for the ASI120MM. I havnt done a lot of planetary as am still deciding on which way to go with filters, so while its kicking around doing not very much I thought I would have a go at this.

Thanks for the idea, David.

Nice! Did you bolt the ASI into the bottom of the dome?

The eyepiece dew heater works great in my dome, but I get some humidity condensing on the inside of the dome if it heats up too quickly. Hmm might need a bit more work...

[DJT (David)]

Hi Dave

Yup, bolted through the bottom using an M6 bolt. I have the same issue with the Dew Heater. Wasnt aware that it might be because its heating too fast so will adjust the heater controller to see what that does.