Bolton Astronomical Society

Old Starlight-Xpress CCD cameras
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Author:  rwilkinson [ Mon Jun 23, 2014 11:31 am ]
Post subject:  Old Starlight-Xpress CCD cameras

I recently acquired an old Starlight-Xpress MX516 cooled CCD camera (its vintage was proved by the 1997 date on its user guide and the control software coming on a 3.5" diskette!). This camera incorporates a 1/3" CCD sensor: much smaller than a DSLR, but still a little larger than the 1/4" chips in my Philips webcams.

It's the monochrome counterpart of the MX5C one-shot colour camera which I used for many years (between 2002-2010), but having a monochrome CCD (without the colour-filter array) it's more sensitive, and uses a 16-bit A/D converter rather than 12-bit. But whereas my colour system included the USB interface, this old mono one still has the original parallel (LPT-port) lead which takes around 20-sec to read each image from the camera.

As with all these small-chip cameras, it's best to use a short focal-length optical system: I use it with my Celestron C8 at f/3.3 (= 670mm), my StarWave80 at f/4.6 (= 370mm), or an old Soligor 200mm lens.
File comment: Testing MX516 with Soligor 200mm lens. My home-made (wooden) bracket includes an old Meade finder to help aiming.
mx516_200mm.jpg [ 311.02 KiB | Viewed 3766 times ]
But unlike modern DSLRs, there's no mechanical shutter to wear out, and no filters in front of the CCD (although it's a good idea to fit your own IR-block). And each raw image-file from this camera is only 300kB: so they won't fill up your hard-disk and are really quick to process!

I've already had some fun imaging with the old MX516, now that I've worked out how to load the image-files into IRIS (saving them as Signed FITS and then using the CONVERTSX command to handle their 16-bit format without saturating). But I'd never worked out a good way to transfer the raw CMY data-files from the MX5C into IRIS (although the AstroArt program and camera driver handles them well).

Author:  rwilkinson [ Mon Oct 05, 2015 11:17 am ]
Post subject:  Re: Old Starlight-Xpress cooled CCD cameras

I've recently added to my collection of "legacy" imaging systems with a Starlight-Xpress HX916 camera. This uses a Sony ICX085 2/3" monochrome sensor, which gives a fourfold increase in capture-area over my MX516 & 16IC cameras, and produces high-resolution 1.3 megapixel 16-bit images. It also includes a peltier-cooling system to improve the sensor's noise performance. These cameras cost nearly £2000 when they were new (around 2002) but can be picked up for around one tenth of that price nowadays.

The camera is provided with an M42 thread on the front (onto which I've fitted a T2 adaptor) but its connection to the computer is rather cumbersome: the camera connects to a separate USB (1.1) interface box which runs from its own 12V PSU, and the software is a bit creaky (although it runs perfectly under Win98, not all of the non-essential functions work properly in WinXP), but it still produces excellent images.
As an alternative to downloading the full megapixel images, the system can also be set to 2x2, 3x3 or 4x4 binning: this considerably speeds up the download time and yields much brighter images for focussing (using a Bahtinov mask) and finding and centering the target.

When I first tried it with my C8 SCT fitted with a f/3.3 reducer (my usual configuration when using 1/4" and 1/3" sensors), it didn't fully-illuminate the HX916's chip, so I saw significant vignetting and distortion of the stars around the edges of the field. But having said that, the larger chip certainly made finding and centering the target much quicker, and I could still get a usable result by cropping the centre of the image:

It produces good results with my 70ED and 80ED refractors even with a focal-reducer fitted, and now I've made a jig to try it with my selection of old Pentax SLR lenses:
File comment: HX916 camera fitted with Pentax 200mm lens. The bespoke (Brian-made) adaptor includes provision for 1.25" filters.
hx916_200mm.jpg [ 232.21 KiB | Viewed 2367 times ]

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