Starlight Xpress SXVR-M25C RGB Bayer 23mm APS Format CCD Camera
But stepping up to the next generation with a Starlight Xpress SXVR-M25C means stepping up your computer, too, doesn't it? Then think on this... When you choose a Starlight Xpress SXVR-M25C, you'll get built-in super high speed USB 2.0 interface (USB 1.1 compatible) for approx. 3.5 second downloads, a built-in autoguider interface and output - compatible with the optional dedicated external guide camera, a built-in dual serial ports for accessory control - a feature that will directly drive filter wheels, GOTO telescopes, etc. Exactly what does that mean? Just ask your computer. That means a single USB cable control for all features! No more Medusa hiding behind your monitor... No more fighting for control room... Now you'll only need one computer to control all of the devices and functions! And what's more? We're talking about very low power consumption... Less than 1 amp at 12v DC. What could make it better? Try being compact and lightweight - only 75mm in diameter x 100mm long - less than 500 grams load on your scope!
Starlight Xpress SXVR-M25C RGB Bayer 23mm APS Format CCD Camera Reviews...
Even though it is a large chip, the download time of a full resolution image is quite short, since the high speed USB2.0 interface that has been upgraded in the newer CCDs does this comfortably in 2.8 seconds. In the older models download time for one single 1x1 binned frame takes some 16 to 18 seconds.
The rear panel of the CCD is very clear. 3 cables are all that are needed. There is only one single USB2 cable required to connect the CCD and the optional external guide head to the computer. Another cable is used for connecting to the driver system of your mount. And of course you need one power cable. The parallel/serial port provides both, power and guiding signal to the external auto guider. The setup can be seen above.
Even though Starlight Xpress recommends a USB cable no longer than 2 m, I find it very comfortable that an even longer cable can be utilized without causing any artifacts to the image. In my case the cable is 7.5 m long, and I have never noticed any operational problems by making use of such a long cable.
The dark signal is very small. I have used only 1 dark frame for each of my images. I can definitely confirm that the effort of taking lots of darks for creation of a master dark frame is not necessary at all. I have never used the dark as it is traditionally used is subtracted from the raw frame. What I do is transform a single dark into a defect map in AstroArt. This defect map will then eliminate a huge amount of hot pixels, which, as a matter of fact, are rare in the first place. Any remaining hot pixels can easily be removed by making use of a median filter mask in Photoshop. I consider this to be a big advantage in comparison to some Kodak-chips in other CCDs, where the accomplished imager has to recreate a huge dark frame data bank every 2 or 3 months, since all chips age over time. Many Kodak chips in different CCDs have a disadvantageous signal to noise ratio, so the serious Kodak-chip-CCD user has to take at least as many dark frames as light frames. In case of SXV M25CI was very pleased to find that this effort is definitely not necessary. The very convincing S/N ratio enables the imager to process the data rather more aggressively and very nice results at considerably shorter total exposure times can be achieved!
Another important consideration is power-consumption of the device. For Astrophotographers like me, who run their observatory on solar power with rechargeable car-batteries (solar panels), low power consumption is an essential issue. I have found a very low average consumption of only 750 milliamps.
The antiblooming is enormously powerful. I have not seen "bleeding" stars yet. Even in long exposure times such as 20 minutes and beyond, no star-artifacts show up. The spectral response is quite high too, at a maximum QE of 60% in red. I am very pleased with this camera since it is able to "see" bright H-Alpha regions in galaxies without usage of appropriate filters! That is very encouraging because in combination with a slow optical system like mine (f/9) the M25C is not supposed to operate with any additional filters; the Bayer matrix would swallow too much light in such a setup.
Will the use of a one shot color camera result in significant loss of resolution? My belief is no, if you operate with an oversampled setup. I have tested monochrome CCDs like SBIG ST 1301E and Starlight Xpress SXV H16. I have compared the resolution power in some images I have taken and I cannot find a dramatic difference that would justify saying, a one shot color CCD is severely inferior to a monochrome CCD. This huge difference was commonly claimed to be certain, but it is not, oversampling granted of course! In my case I work at an image scale of 0.8 arc seconds per pixel. Since the OSC data an easily be converted into a so called 'pseudo-luminance' (channel mixer e.g.) this data can then be processed quite aggressively with deconvolution or wavelets like a classical luminance frame taken with a mono-CCD. In case off undersampling (less than 2 arc seconds per pixel) you will surely find loss of resolution in comparison to a monochromatic CCD. Also star color will not be proper, as it might occur, that this color data from one star is cast onto one pixel that is located exactly under the green, red or blue bayer matrix. by averaging these 4 pixels the true color information will be lost! Another good reason for significant oversampling! The real big advantage of monochromatic CCD other than the opportunity to use narrow band filters is to get much better color data, particularly in objects with weak signal. The OSC can do a great job in objects with a strong signal like planetary nebula, bright clusters and very bright galaxies. On the other hand there are some consideration that shall be gone through carefully before picking a CCD:
- Focal length of the optical system the CCD is supposed to be attached to. It is obvious that a one shot color CCD operating with an optical system resulting in an under sampling higher than 1.5 or 2 arc" will suffer from less resolution compared to a monochrome CCD since the Bayer matrix (4 pixels) has to be summed up. In any system that operates beyond this, say distinctly below 1 arc" the difference will no longer show up so easily.
The quality of your observation site: if the observatory is located in a place that provides the imager with exceptional good conditions like high transparency, seeing far better than let`s say 2 arc" FWHM, and reliability in steady weather conditions that allow imaging night after night, then I would recommend to pick a monochrome CCD and do LRGB imaging. In more "average and normal" cases, like mine, meaning moderate transparency and seeing frequently worse than 2" I would strongly recommend to go for an OSC, because you will never be able to take the full advantages a monochrome CCD would grant. In addition to that fact, it might be given to deal with weather-conditions that allow imaging for one night, but you can not be sure if the next days will give you the opportunity to complete the object, since you will need much more total exposure time to obtain colors. In my case for example I sometimes have one single night in one month, so I love to take the advantage of my OSC making every single frame count and to be sure to finish the object in a reasonable amount of time!" -- Dr. Dietmar Hager, RAS
Starlight Xpress SXVR-M25C RGB Bayer 23mm APS Format CCD Camera Specifications...
- CCD type: Sony ICX453AQ SuperHAD CCD with ultra low dark current, Bayer RGB matrix and vertical anti-blooming.
- CCD Full resolution Pixel data: Pixel size: 7.8uM x 7.8uM, Image format: 3024 x 2016 pixels.
- CCD Image area: 23.4mm (Horizontal) x 15.6mm (Vertical).
- CCD quality: Grade 1 or better - No bad columns, no dead pixels, no more than 50 'hot' pixels (saturated in <10 seconds).
- Spectral Response: QE max at 540nM (~60%), 50% roll-off at 400nM and 650nM.
- Readout Noise: Less than 12 electrons RMS - typically ONLY 7 electrons!
- Full-well capacity: Greater than 25,000 e- (unbinned).
- Anti-blooming: Overload margin greater than 800x.
- Dark current: Dark frame saturation time greater than 100 hours. Less than 0.02 electrons/second @ + 10C ambient.
- Data format: 16 bits.
- System gain: 0.4 electrons per ADU
- Computer Interface: Built-in USB 2.0 compatible interface. Also works with USB 1.1.
- Image download time: Typically 3.5 seconds full resolution using USB 2.0, approximately 8 seconds with USB 1.1.
- Power requirements: 115VAC / 240VAC @ 12VA, or 12VDC @ 750mA max.
- Cooling system: Regulated constant current cooling supply with single stage thermoelectric cooler to give a CCD temperature of approximately -30C below ambient.
- Size: 75 x 100mm black anodised aluminium barrel with 42mm 'T2' thread at the CCD window end & input/output plugs at rear. CCD alignment screws are provided for setting the chip parallel to the focal plane.
- Weight: approx. 400g.
|Color or B&W?||Color|
|Series||Starlight Xpress SXVR|
|Warranty||1 Year Warranty|
- Starlight Xpress SXVR-M25C CCD Camera
- Cooling System
- Power Cable
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