All Sky Camera Revisited

[tonyowens_uk]

Gina
Based on what we read your approach to developing this camera to be as simple as possible (but no simpler) and how you've allocated your time to testing is exemplary.

Its a bit of a pain to have to put the remote focusing back in but youve already developed this module if I understand your previous sky camera efforts so hopefully it will be 'just' a packaging problem.

And while that is being designed and built I'm sure I'm not the only one curious about the hermeticity and environmental resistance of heavy duty 3D printed structures like those you've used. Being able to monitor the dessicant condition visually from afar is a nice touch. how that changes in the face of daily thermal hilo's and rain and vibration will be interesting.

Thanks for the filament material reference. I'm only getting started myself.

Tony

[AngryDonkey]

Great stuff, I am particularly impressed by the water cooling!

10 hours ago, Gina said:

Fortunately, making a new casing to accommodate one of the small stepper motors is just a matter of redesigning it and printing a new version.  I think it will need the 4" dome though as the 3" one is already a tight fit.

I'm in  a similar position just now where I have to make up my mind if want to install remote focussing or not and am looking at options. Not sure if this could work with your setup but there was someone on the all-sky facebook group who implemented the focus mechanism by rotating the camera and not the lens. This worked well on the ASI camera because you can just screw a threaded rod at the bottom and all it need then is a gear and a motor placed underneath (and a permanent clamping mechanism for the lens). The only downside is that rotating the camera will also rotate the USB cable going to the camera so the adjustment range is limited but apparently it is enough for fine focus.

Eventually my camera will be remote hosted so I won't be able to tinker with it if things go wrong so for me it's really a toss up between the ability to remote focus vs the extra complexity of the focus mechanism which might cause issues in itself.... Never easy ?

 

[Gina]

Thank you both for those comments. 

Seems the dew heating wants increasing as there is some dew around the edge of the dome.  Now surprising as we has a frost and the observatory roof was covered with frost at 7am, now melted in the morning sunshine. 

[Gina]

The colour change silica gel is still showing bright orange so the sealing has worked.  By this time the colour would have changed to green even indoors in lower humidity.  The water in the saucepan I'm temporarily using as a reservoir is still cold.  I do have a radiator if needed to cool the water but looks like this may not be needed.

[Gina]

Removed ASC et al  from observatory and brought it indoors.  It's still out of focus so I'll reset the focus and think about giving it another try tonight.

Edited March 26, 2019 by Gina

[Gina]

Been manually focussing and there certainly is a difference with and without the dome so that shows the need for remote focussing as it isn't possible to manually focus the lens with the dome on.  That's aside from the difficulty of actually focussing by hand.  OK so theoretically is should be possible to make allowance for the dome - or keep removing and replacing the dome between focussing.  Maybe I could get focus nearer this way but accurate focus would be extremely difficult.  I shall investigate remote focussing.

Two images zoomed in to about the same extent.  First without the dome and second with.  I tried to get the focus fairly near without the dome but with the frame capture period of several seconds this is not easy.  Note focussing on the horizon, not the bird feeder or nearby trees, though the bird feeder does illustrate the difference the dome makes.

[Gina]

Thought I'd try the ON-OFF-ON-OFF dome type manual focussing but it's darn nigh impossible!  May have a coffee break and try later but...

Edited March 26, 2019 by Gina

[Gina]

Amazing what a cup of coffee can do - brain reactivated ?  Had a thought for reducing the time between images - 2 possibles - binning and/or just downloading the centre part of the image (Region Of Interest).  Binning made the image a bit coarse but ROI worked fine.  Can also capture more images before the SSD fills up.

[Gina]

Using ROI I have repeated the manual focus and this is the best I can get.  TBH I think it's approaching the best the lens will do and is considerably better than last night.  Maybe it's worth a test tonight.  Here are some images.  The far range of hills are about a mile away.  This is looking out of the east window of my living room.

1. Full view - no dome.
2. Zoomed in - no dome.
3. Zoomed in - with 3" dome.

 

Edited March 26, 2019 by Gina

[JamesF]

It does look as though there's perhaps a little scattering of light in the dome.  Looks like it's another clear night tonight so hopefully you'll be able to test it this evening.

I have been wondering about using flat glass instead of a dome (set at an angle, so rain runs off).  I might have to experiment with it once I get the observatory finished.

James

[Gina]

Flat glass will give you a lot of distortion as well as internal reflections.  Ultra thin glass might work or possibly Baader film clear (rather than the sun blocking sort).

[Gina]

Need more dew heating and got fed up with messing about with resistors or nichrome wire with all the mounting problems so bit the bullet and ordered a proper dew heater.  Dew Heater Module - All Sky Camera

 

[Gina]

Everything back on and in observatory.  The focus is tons better than last night.  Here is a far hill on the edge of the view at full zoom.  This is the best I can do with manual focus.  Tonight will tell assuming it remains clear as forecast.

[Gina]

Exposure increased to 2ms to show the ground level.  Second image shows the north view rotated to show "normal" view - sheds and bungalow.

Edited March 26, 2019 by Gina

[Gina]

Having used ROI for manual focussing it occurred to me to use it for normal imaging to cut out all the black outside the sky view.  That will save some disk space when saving images.

Edited March 26, 2019 by Gina

[Gina]

Not too long until sunset and possibility of seeing stars now.  Looking forward to seeing if I've conquered the focus.  Exposure still 1ms and gain 0.  Camera temperature -16°C.  Not that it needs it - still running test setup.

[Gina]

It's showing signs of mistiness - the hills to the south are looking decidedly murky ?

[Gina]

A bank of cloud to the south, a few contrails and the sun shining on the sheds...  Lots of wispy clouds.

Edited March 26, 2019 by Gina

[Gina]

Some redness in the sky.

[Gina]

A few lights but where are the stars???  Exposure 10s, gain 0, temperature -13°C.

[Gina]

Ah, a handful of the brighter stars and maybe a planet of two.   Exposure 20s, gain 0, temperature -14°C.

[Gina]

Exposure 60s, gain 0, temperature -13°C.  Plenty of stars showing now and very much better than last night but they are out of focus, not a lot, but...

Edited March 26, 2019 by Gina

[Gina]

Exposure 60s, gain 200, temperature -14°C.  Next door have turned their quadrillion candle power floodlight on  ?  I expect they'll turn it off later - they don't usually leave it on.

Edited March 26, 2019 by Gina

[happy-kat]

Wow it's bright. Better stars than last night.

[Gina]

Yes indeed.  To both.  Stars a lot better than last night but still not quite in focus.  It could do with motorised focussing to get that last bit.  Won't do that immediately though, I'll wait for the new dew heater to arrive at least.