Features and design :
In manufacturing this monochrome large format CCD Starlight Xpress departed from their tradition of installing Sony chips, that are well known and appreciated for their very low dark current signal. A KAI4021M from Kodak was used in this CCD and the reason for this decision was that unfortunately Sony do not manufacture large mono chips.
In order to diminish the undesired negative effects of the higher dark signal, SX introduced a 2 stage Peltier element to cool down the chip to about 40°C below ambient.
Pixel size is 7.4 microns in a 15.15mm square area. This results in 2048 x 2048 pixels; a total of 4.19 Megapixels. Nevertheless the download time of a full resolution image is quite short, since the high speed USB2.0 interface does this comfortably in 2.8 seconds.
The H16-chip covers about 2/3 of the area of the very large M25C Sony chip.
You can find more features and detail of technical specifications here:
Practicality
I appreciate the low weight of only 390g. This is very convenient for my scope that has quite a long back focal distance. So the mechanical lever is really huge and therefore a "light" CCD is what I need in order to prevent differential bending in the mechanical axis. This might also be a huge advantage for any scope with long backfocus or in those that are lightly constructed such as some Newtonians.
The long back focal distance can be seen here.
The dark signal is very small as You can see in the 2 dark frames below. In winter-time when ambienbt temperature is below +5°C I do not use any darks in 1x1 in my imaging; however in summer-time, when ambient temperature is 20°C I do take a couple darks in 1x1 as it makes preprocessing much easier, but still, it is possible to deal without them.
At least a couple (5) darks in 2x2 binning are necessary in any case of ambient-temperature. It seems not to be necessary to take more darks...luckily. This is also a big advantage in comparsion 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 the time. I find it most interesting that it does not make a big difference in the preprocessing result if the ambient temerpature the dark was taken varies in an ampitude-range of 5 °C. 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 H16 I was very pleased to find that this effort is definitely not necessary.
1x1bin 8 min dark (left) - 2x2 bin 5 min dark (right)
Here is a comparsion to 2 Kodak-chips
KAF-1301E/LE and Kodak KAI-2020CM. Both darks were taken at -25°C and 10 minutes.
Certainly those CCD Cameras are very sophisticated items and splendid images have been taken with those CCDs. Gorgeous results can be found all over the web. It is not my intention to offend anyone, but there is a significant difference in those chips and therefor pre- and postprocessing is much more demanding and time consuming. (In order to hold down the noise, methodes like dithered guiding, bias frames, a dark to light frame ratio of 1:1 etc become necessary...taking darks and bias frames and recreate them all 2-3 months to compensate aging of the chip finally accelerate the aging of those chips...) In unsing low noise chips, you can make every frame count for the image and lifespan will be longer.
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 900 milliamps.
The antiblooming is powerful. I have not seen "bleeding" stars yet in 1x1 binning. The spectral response is not really strong, as there are CCDs using Kodak KAF-1301E/LE Chip, that have a QE over 70%. That is very encouraging cos you gather the signal rather quickly as I have found in a test. I have also tested a one shot color chip KAI-2020CM. However on the downside of this chip the signal to noise ratio is really very bad: what you gain in signal you tend to loose in noise - so, many darks are vital to alleviate that problem. Anyhow, H 16-QE is quite good with a very nice 55% peak in green light.
Astronomik Filters in my FLI filterwheel and the response-curve of KAI4021M (measured with cover-glass)
As You can see in the first light image below the H16 has even imaged the H2 regions in the irregular galaxy NGC 4449 successfully, without using a H-Alpha filter.
Here is the First light result taken with my 9" TMB Apo f/9 and the H16 - NGC 4449.
Luminance: 3 hours 1x1 bin (2min, 4min, 8 min and 12 min)
R: 6x9 min 2x2 bin
G: 6x5 2x2 bin
B: 6x10 2x2bin
Image acquisition in AstroArt4, Preprocessing in Maxim DL (calibration, alignment, DDP) and CCD sharp (deconvolution), postprocessing in PS CS" and PixInsight LE (background) Color balancing in PS CS2
(It was honoured by becoming a NASA APOD)
Here is another result taken with SXV H16 - Sunflower Galaxy
CCD: SXV H16 - 2.7 hours - luminance; 6 hours R,G,B (2 hours each channel 1x1 binned)
Software: AstroArt4 image acqu. guiding. Maxim DL preprocessing
Processing: postprocess. PS CS2 and Pix InSight LE; Color balancing in PS CS2
After successful tests I have decided to purchase an SXVF H16 for myself. In the following image I have not applied any dark frames.
NGC 4490+4485
CCD: SXVF H16 L: 15x9 min; R,G,B 2x2 bin 7x9 min (FLI 2" Astronomik Filters)
Software: AstroArt4 image acqu. guiding, preprocessing: Maxim DL; Registax; CCD sharp. no dark frames.
Processing: postprocess. PS CS2 and Pix InSight LE (R=1.3; G=1; B= 1.1)
After conducting G2V-Star balance twice on two different G2V stars at 70° altitude with my entire image-train (the TMB triplet, the 2 flat mirrors, the Astronomik type IIc filters and H16) I calculated these parameters for RGB color combination and found these numbers to work properkly in Maxim DL I am planning on conducting a couple more in different altitude to see the difference...r=1.3; g=1; b=1.2
