So, new all-sky housing from my friend Jason at All Sky Optics . I'm a bit of a difficult customer, since I wanted a set up that I could use with a variety of different makes/models of camera, rather than just one single camera. That means that instead of having a single camera cradle permanently fixed into the mounting, I have a range of them which I can stick in (and remove, with care) using UHB tape.
Here's the new setup attached to one of the runoff rails of the observatory (low enough to be missed by the roof!)
The enclosure has a built in dew heater ring around the camera mount to keep the dome clear. I've also added some silica gel sachets inside the box to keep the internal humidity low - every little helps.
Currently I have an Altair 224C camera mounted in the system with a 2.1mm lens. The choice here was determined by a number of factors...
* No need to have a really wide field of view because my sky view is limited by house, trees, etc
* Cannot use a mono camera as I have a security camera nearby that has an IR illuminator
* A relatively square sensor (4:3) works better than a widescreen sensor like the 290C
* Have to choose a camera with a 12.5mm (CS) mounting - larger sensors often have a 17.5mm (C) mounting, meaning short focal CS lenses cannot be used.
I have also been tweaking SharpCap just a bit to help support the all-sky use. The very latest SharpCap 4.1 (4.1.10949) contains two new features that help make this set up easier to run
* Option to allow saving from RAW8 to compressed WMV video.
Why? WMV makes for nice compact recordings, but cannot record RAW data directly as the compression would destroy the bayer pattern. However, if you run the camera in RGB mode then it is hard to get rid of the hot pixels without dark frames, and you can't use darks as the exposure varies (auto exposure). So... Run camera in RAW8, set Dark Subtraction to 'Hot Pixel Removal only', set save format to WMV (having turned on the option to allow this) and SharpCap will do the hot pixel removal on the raw frame then debayer and save to WMV.
* Command line option '/runsequence' to start a sequence automatically when you run SharpCap
This is added for being generally useful, but particularly because I intend to use the sequencer tool to automate the captures (previously I used python scripting which was less user-friendly).
Currently I am using this sequence
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SEQUENCE LOOP 100 TIMES WAIT UNTIL EVENT CivilDusk CAMERA OPEN ALTAIRGP224C TARGETNAME AllSky LOAD PROFILE "AllSky RAW8 to WMV" DELAY 10 CAPTURE START WAIT UNTIL NEXT EVENT CivilDawn CAPTURE STOP CAMERA CLOSE END LOOP END SEQUENCE
Camera settings that are being used are as follows (the important ones only included)
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Output Format=WMV file (Lossy Compression, *.wmv) Colour Space=RAW8 Auto Gain with Auto Exposure=Up to 1600 Auto Exp Target=70 Frame Rate Limit=1 every 30 seconds Analogue Gain=1600 Exposure=36.585s(Auto) Hot Pixel Sensitivity=15 Subtract Dark=Hot Pixel Removal Only
I guess after all that I ought to share some video... Not the clearest of nights, and youtube has rather messed up the stars in places, but you get the idea