New wide field meteor camera - part 1

[michaelmorris]

After 2 years of sterling service I’ve retired the Samsung SDC-435 and 2.1mm f2 board lens-based all sky meteor camera and replaced it with one based on a Watec 902H2 Ultimate and Computar HG2610 AFCS 2.6mm f1.0 DC auto iris lens. It’s all housed in a modified CCTV housing with a plastic dome on top. The manual for the lens states that the field is view is 144o across the diagonal, but in practice I think it’s a bit less. The old housing won’t take the much larger diameter lens.



I bought a relatively cheap CCTV housing from EBay and removed the glass. I drilled two holes in the back to take the cable flanges and a square hole in the centre of the back plate to take the inner and outer cheap computer heat sinks. The dome is mounted on a sheet of 1 cm thick recycled plastic board I had hanging around. The board is bolted to the front (i.e. top) to the housing. The front overhang of the housing lid was sawn off to allow lid to open once the board was fitted. The light shield I made from a trimmed down plastic ‘Celebrations’ sweets box painted black on the inside and white outside. It’s bolted to the plastic mounting board with some washers between the rim of the box and mounting board to allow water to drain away readily.



The 145mm diameter acrylic dome came from Project Plastics in Colchester ( www.projectplastics.co.uk/acrylic-domes.html ) via their EBay shop. stores.ebay.co.uk/project-plastics?_trksid=p2047675.l2563. Because of the high postage charge, I took the opportunity to buy a second spare dome at the same time. The plastic is a little thick, but the finish is good and it seems to add surprisingly little distortion. The dome is sealed with a piece of rubber mouse mat cut to size and sealed at the base with some liquid gasket. It’s held down with some mirror clips bolted to the plastic board. So far it’s survived at least two pretty heavy storms and there are no leaks.



More to follow ...

[michaelmorris]

PART 2

Inside dome the is an off-the-shelf 12v CCTV housing heater and thermostat and a 25mm 12v maglev computer fan to keep air moving around the inside of the dome. With the very limited running so far (5 nights), I’ve had no problem with condensation inside the dome.



Inside the camera and lens are mounted on an Opticron 42606 Quick Release Plate & shoe from Sherwoods Photo this provide both an ideal spacer to get the camera in the centre of the housing aperture and allows swift removal of the camera and lens.

In an effort to reduce noise in the camera, I’ve cobbled together a crude cooling system consisting to a pair of copper roofing ties connected to the camera base mounting bolt. These copper strips are sandwiched between the inner and outer heat sinks at the base of the housing and a 12v fan is fitted to the inner fan. I suspect this cooling system will be pretty ineffective, but it’s worth a try.



The signal out from the camera is connected via a cheap ground loop isolator.

At the rear, the housing is mounted on to a TV aerial pole with a pair of TV aerial brackets bought from B&Q. The brackets are padded out with some more plastic board so the U-bolts on the mounting brackets don’t project too far into the housing. I had to take a Dremel to the inner camera mounting rails so allow enough clearance for the retaining nuts for these TV aerial brackets.



The whole system is on a timer so that it turns on 40 minutes before it starts recording. This is to try to ensures the heater and fan have time to clear any condensation inside the dome before recording starts. Recording is controlled using UFOCapture 2 software. sonotaco.com/e_index.html