ALMIRA OBSERVATORY
 

     A suburban observatory in Worcestershire, UK based on a metal garden shed

           
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  Construction 16 - All Sky Camera

 

Towards the end of 2012 I decided to construct an All Sky Camera to mount on the observatory.  I already had a Samsung SDC-435 low light CCTV video camera which is used by Worcester Astronomical Society for public outreach work.  The infra-red blocking filter had been removed from the camera to provide better response to hydrogen alpha (QCUIAG).  When not in use by the society, it now acts as my all-sky camera. 

The camera is mated with a 2.1mm f2 board camera lens (with an advertised 160o field of view) bought on eBay for just f7.49.  The two are mated using a board (M12) lens to C mount adaptor purchase from Stock Optics    To protect all the optics and electronics from the elements, the whole caboodle is mounted in an IP55-rated electrical cabinet.

                     Camera in retracted position

The electrical cabinet is rather oversized because this was the cheapest exterior-grade electrical cabinet I could find that was deep enough for me to mount a small acrylic dome on the top.  I also wanted the cabinet to be tall enough to allow me to easily retract the camera from the dome for focusing.  The dome came from Henrys Electronics and cost just £12.  I removed the screws used to fix the lid to the box and replaced them with five toggle catches.  The empty screw holes were filled with mastic.  The finished enclosure was mounted to the side of the observatory on a television mount pole and bracket.

12v power cables and signal cables run through a hole in the observatory wall.  The camera is connect to a computer using a cheap KWorld DVD Maker USB analogue to digital converter.  Video capture is via the excellent HandyAvi software.  Videos of meteors and ISS passes captured by this system can be found here.

   

 

 

Since these photographs were taken I have added some black wooden light baffles around the outside of the box to cut down the internal reflections off the inside of the acrylic dome caused by local security lights.  I have also added 12v dew heaters made from small resistors and a 12v cabinet heater (£3) originally designed for use in CCTV enclosures.  These have significantly reduced the instance of dewing up of the dome. 

I have recently noticed a build-up of condensation inside the dome on hot sunny days.  To combat this, my plan is to install a mechanised insulted waterproof cover for the dome.  This would be on a timer plus it would also automatically close in the event of rain.  I would use a rain sensor to trigger this.  A cheap 12v servo may be a suitable system for actuating the cover closure/opening.

 
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Last updated -  27th April 2013

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