A new release of AstroDMx Capture for Linux (0.50.9) PLUS a simultaneous release for the Raspberry Pi

AstroDMx Capture for the Raspberry Pi Logo

Whilst implementing AstroDMx Capture for Linux for the Raspberry Pi computer, some additional features were required that will also prove to be useful in the general release. One such feature is a function to reduce any lag in the image being previewed from UVC cameras. This will enable the user to set the point where lag is at a minimum and frame rate is as high as possible, commensurate with the lag reduction. This is particularly important during focusing and setting exposure etc.

The CPU useage has also been generally reduced and in particular for the QHY cameras. A number of other post-release issues have been fixed.

The result, is the simultaneous release of version 0.50.9 for the Raspberry Pi ARM processor and release version 0.50.9 for x86_64 processors.

Screenshot  showing Splash screen of AstroDMx Capture for the Raspberry Pi

The Raspberry Pi Version of AStroDMx Capture for Linux works with the Official Linux OS for the Pi: Rasbian Stretch with Desktop.

AstroDMx Capture for Linux maintenance (Version 0.50.4) released

Nicola has released a maintenance release (0.50.4) of 

AstroDMx Capture for Linux.

This version fixes a couple of bugs and allows real-time frame correction in frame-integration mode.
Although this release follows quickly on the heels of the previous version, it is worth installing it to replace version 0.50.1.

Nicola is working on, and hoping to release shortly, a full version of AstroDMx Capture for the Raspberry Pi computer. Although we have successfully tested previous versions of AstroDMx Capture for Linux on the raspberry Pi computer, Raspberry Pi test 1  ;  Raspberry Pi test 2 Nicola has not yet taken the Pi version to the release stage. Watch this space

A new release of AstroDMx Capture for Linux (Version 0.50.1)

A new release of AstroDMx Capture for Linux (Version  0.50.1)

The previous version of AstroDMx Capture for Linux (Version 0.10.2.0) was released in March 2018. Since that time Nicola has worked tirelessly to produce a new version that supports more cameras, has more features and has greater efficiency.

A series of factors has delayed the release until this time. Problems with manufacturer’s SDKs have produced significant delays and have sometimes had to be programmed around. Also, several more cameras have been implemented. Cameras with sensors having very large pixel numbers, produce significantly more data and this can have performance consequences that had to be addressed. Cameras that have been implemented have ADCs of different bit depths. These bit depths are 8 bits, 12 bits, 14 bits and 16 bits. The data stream produced by cameras with 12 bit, 14 bit and 16 bit ADCs have to be placed into a 16 bit container such as a SER file, FITs file or a Tiff file. Moreover, the data stream has to be displayed so that the object being imaged can be viewed for focussing and image composition purposes. Nicola has implemented a number of non destructive transformations on the displayed data (that in no way affect the data being saved). These transformations allow very faint objects to be viewed and adjusted easily, whilst not affecting the data being saved.

Screenshot of the new splash screen of AstroDMx Capture for Linux

AstroDMx Capture for Linux has grown over the past two and a half years into a veritable Magnum Opus. The Source code has grown to 32,118 lines of code (not including external dependencies and SDKs), with an additional 7,331 lines of internal documentation (comments) to facilitate maintenance of the code. Many of the ‘lines’ of code or documantation in fact, take up two or more actual lines. To put this in familiar terms; a book such as the 2006 Yearbook of Astronomy, edited by the late Sir Patrick Moore contains 39 lines per full page of text. This means that if AstroDMx Capture for Linux was to be printed in a book such as this, it would require two volumes of at least 506 pages per volume, to contain all of it (The Yearbook contained 331 pages). When projects reach this size, they require a very significant amount of time to maintain and develop.

In common with many Linux projects, Nicola has now included a Donate button (near the bottom of the right hand side of the program interface). A user is free to use the software as usual, but if the user finds it to be useful, please consider making a donation by the simple procedure, of an amount decided by the user. Some software authors call this a ‘coffee donation’, because a donation of say £5 is like buying the author a couple of cups of coffee. This is, of course, not obligatory, but it would help motivate the spending of considerable amounts of time maintaining and developing the software.

The new, pre-release version was tested by capturing data on the Orion Nebula using a ZWO ASI178MC (USB3.0, 14 bit ADC) camera at the Newtonian focus of a Skywatcher Explorer 130 PDS 130mm, f/5 Newtonian. 50 x 4s exposures, 50 x 20s exposures, and 10 x 60s exposures were captured with matching dark-frames, all as 16 bit Tiff files. The groups of images were stacked in Deep Sky Stacker running in Wine and the resulting images were combined in the Gimp 2.10 to produce a final image of high dynamic range, revealing the faint and bright parts of M42/43 without saturating any part of the nebula.

Photograph of the equipment used to capture the data

Screenshot of AstroDMx Capture for Linux capturing the data.

Final image of M42/43

List of cameras implemented in AstroDMx Capture for Linux at the time of writing
Astronomy USB cameras
DMK 21AU04.AS (8 bit ADC)
DFK 21AU04.AS (8 bit ADC)
DBK 21AU04.AS (8 bit ADC)
ZWO ASI120MC (USB2.0, 12 bit ADC)
ZWO ASI120MC-S (USB3.0, 12 bit ADC)
ZWO ASI120MM-S (USB3.0, 12 bit ADC)
ZWO ASI178MC (USB3.0, 14 bit ADC)
QHY 5L-II-M astronomy camera (USB2.0, 12 bit ADC)
QHY 5L-II-C astronomy camera (USB2.0, 12 bit ADC)
SVBONY T7 W2568A High-speed camera (USB2.0, 12 bit ADC)
Atik 314L CCD camera mono (USB2.0, 16 bit ADC)
Atik 320E CCD camera colour (USB2.0, 16 bit ADC)
Orion Starshoot Solar System Color Imager IV (USB2.0, 8 bit ADC)
Bresser MicrOcular Full HD Digital Camera (USB2.0, 8 bit ADC)
SVBONY SV105 HD (8 bit ADC)
Altair (Orion Starshoot) USB eyepiece (USB2.0, 8 bit ADC)
USB cameras
DMK 37AUX273 machine vision camera (USB3.0, 12 bit ADC)
ELP 1.3Mp CMOS board-level HD USB camera (8 bit ADC)
Lucky Zoom 5Mp microscope USB CMOS camera (8 bit ADC)
Vimicro USB2.0 UVC PC camera (e.g. Maplin USB2.0 Microscope) (8 bit ADC)
USB Capture cards
KWORLD DVD MAKER 2 (8 bit ADC)
UVC capture card (Motion-JPEG only) (8 bit ADC)
EasyCAP (Motion-JPEG only) (8 bit ADC)
USB webcams
Sweex WC066 HD webcam (8 bit ADC)
Sweex WC070 ViewPlus (8 bit ADC)
Sweex WC035V2 VGA webcam (8 bit ADC)
Philips SPC900NC including SPC800 and Philips 740 flashed to SPC900NC (8 bit ADC)
Philips 690 Vesta Pro Webcam (8 bit ADC)
Logitech HD C525 (8 bit ADC)
Microsoft LIFECAM 2 (8 bit ADC)
Creative Webcam Live (8 bit ADC) Bayer output only.
All Video 4 Linux cameras.
The software also controls the ZWO USB filter wheel.

AstroDMx Capture for Linux is under constant development, so this list of supported cameras will grow over time.

List of Linux Operating systems and desktop environments tested to date with AstroDMx Capture for Linux
Debian 9, Xfce, LXDE, Cinnamon, GNOME 3, MATE, Plasma
Fedora 24, 25, 26 Gnome 3
Fedora 26, 27, Cinnamon
Fedora 28, 29 Xfce, Cinnamon, Gnome 3
Linux Mint 18.2 Cinnamon, MATE, Xfce
Kubuntu 16.04 LTS
Kubuntu 17.04
Xubuntu 17.04, 18.04
Lubuntu 17.04
Ubuntu Gnome, Gnome 3 or classic
Ubuntu 16.04 with Unity (with the additional download package)
Ubuntu 17.04 with Unity (with the additional download package), and Ubuntu 18.04
Peppermint OS
Antergos Linux
PC Linux Mate
Mageia Linux
Elementary OS. Runs from the command line only at the moment

AstroDMx Capture for Linux can be downloaded HERE

Converting a DashCam to a stand-alone electronic eyepiece

A frequent problem encountered at star parties is that many visitors are not easily able to see through an eyepiece for a number of reasons. Sometimes, wearing spectacles presents a problem to the inexperienced person, as does getting to grips with the eye-relief of a given eyepiece. Of course, practice makes perfect, but practice is not an option for many visitors to star parties.
Often the solution is to use an analogue video camera and a TV screen or a camera and a computer on which to display the video stream.
I experiment here with the idea of modifying a DashCam as a stand-alone electronic eyepiece having its own built in screen. The device I experimented with was a cheap (£29.99) DashCam from Amazon.

Needless to say, this modification will invalidate the warranty, so it is essential to test the camera to make sure it is working, before any modification is attempted.

This camera has a 3 inch screen on the back, which is just large enough to be useful for this modification. A larger screen would be better, but would also be commensurately more expensive.

An degree of brute force was required to separate the outer cylinder from the two pillars to which it was attached. There was no clue how this part was constructed, so there was an element of luck involved. The pillars were cut off as they would have been in the way later on.

The lens was attached via a standard 12mm webcam thread but had been glued in place to hold the focus of the camera during the inevitable vibrations experienced by a DashCam. The glue was chipped away using a sharp blade, until the lens could be unscrewed.

A standard Mogg adapter was screwed into the eyepiece thread. The IR cut filter is part of the lens assembly, so a separate filter will be required to get the correct colour balance. In this case, an IR filter removed from an old webcam was attached inside the bottom of the Mogg adapter. However, a low cost UV/IR cut filter could have been screwed onto the end of the adapter.

IR cut filter from an old webcam glued at the bottom of the Mogg adapter was added later.

The camera was then ready for testing on the Moon, in this case, using a 127mm Maksutov on an AZ GOTO mount.

It will be noticed that in the photograph above, there is a blue tinge to the camera screen. This is not a true representation of what the eye sees. LCD screens produce a light that is rich in the blue and photographs of these screens almost always amplify the blueness of the image that the eye doesn't see. The best way to photograph a CCD screen that is displaying an essentially monochrome image such as that of the Moon, is to photograph the screen in B/W as in the two images below.

The screen is displaying the Copernicus/ Kepler region of the Moon in this shot.

In this shot, Palus Somni can clearly be seen

The modification clearly works and the next step is to test how successful it is at a star party. Although the camera has an internal battery, it can be powered from the same power pack as the AZ GOTO mount on which the telescope is mounted.

Correcting pixel vignetting with flat-fields is essential for the SVBONY SV105 camera

A SV105 camera was fitted with a double polarising filter which was tuned to give the correct exposure for the Moon. The camera was placed at the Newtonian focus of a Skywatcher Explorer 130 PDS 130mm, f/5 Newtonian mounted on a Celestron AVX EQ, GOTO mount.

Previously, using an overcast sky, a white styrene 1mm, Plasticard, plastic sheet was placed over the front of the telescope and AstroDMx Capture for Linux was used to capture flat fields and calculate a master flat field. The flat fields were captured with saturation turned off, giving an effective monochrome image.

Master unsaturated flatfield

Note the pixel vignetting gives the opposite effect to classical vignetting as has been reported here previously. With classical vignetting, the centre of the image would be lighter than the peripheral areas. Also note, that the vignetting is asymmetrical.

This master flat field could have been used to do real-time corrections to the video stream in AstroDMx Capture for Linux, but in this case real-time correction was not used as a comparison of flat field corrected and uncorrected results was intended.

Four overlapping, 1000 frame SER files were captured with AstroDMx Capture for Linux so that the whole of the 98.3% waxing Moon was covered by the four resulting panes.

The best 500 frames of each SER file were stacked in Autostakkert 3.1.0 running in Wine; firstly without flat field correction and then with flat field correction, producing four uncorrected and four flat field corrected panes.

The unprocessed data were stitched in Microsoft ICE running in Wine to produce an uncorrected image of the Moon and a flat field corrected image of the Moon. The two images were then made into a blink animation to show the effect of Flat field correction.

Uncorrected vs flat field corrected, unprocessed data animation

The benefit of flat field correction is evident from inspection of this animation.

The flat field corrected image was wavelet processed in Registax 5.1 running in Wine and post processed in the Gimp 2.10

Flat field corrected image

Closer view

Flat fields need only be captured once and can be used many times.
With the correct procedures, the SVBONY SV105 camera is a very capable, low cost, lunar and planetary camera.

58% waxing, gibbous Moon with AstroDMx Capture for Linux and a DMK 37AUX273 (USB3.0, 12 bit ADC) camera

A DMK 37AUX273 (USB3.0, 12 bit ADC) camera, fitted with an 850nm IR pass filter was placed at the prime focus of a Bresser Messier-AR-102-AS ED refractor, mounted on a Skywatcher Star Discovery AZ, GOTO mount, and AstroDMx Capture for Linux was used to capture 2 overlapping, 5,000 frame SER files of the 58% waxing, gibbous Moon at full resolution 1440 x 1080, in a twilight sky. The best 25% of the frames in the SER files were stacked in Autostakkert! 3.10 and wavelet processed in Registax 5.1 running in Wine. The two resulting images were combined in Microsoft ICE running in Wine and post processed in the Gimp 2.10.

58% waxing, gibbous Moon

Full Size

Screenshot of AstroDMx Capture for Linux capturing data from the 
DMK 37AUX273

The DMK 37AUX273 again proving that it is a very capable Lunar imager.

Comet 21P/Giacobini-Zinner

Comet 21P/Giacobini-Zinner was imaged using AstroDMx Capture for Linux with a ZWO ASI178MC camera at the prime focus of a Bresser Messier-AR-102-AS ED refractor, mounted on an iOptron Cube Pro AZ, GOTO mount. 10s, 16 bit TIFFs were collected with matching dark frames. The images were stacked and dark frame corrected in Deep Sky Stacker running in Wine. The image was post processed in the Gimp 2.10.

Comet 21P/Giacobini-Zinner

Alignment was difficult from the site chosen, and tracking was not perfect. However, about a third of the images captured were good enough to stack. The exposures were of limited duration due to tracking issues. Nevertheless, the comet tail and star colours showed up quite well. Focus was a little soft and is not as easy to achieve as with a dual speed focuser.


The ZWO ASI178MC camera

This camera has a 14 bit ADC so it is much less likely to saturate. AstroDMx Capture for Linux auto detects the ADC bit depth and so correctly places the data into either the bottom or the top bits (User defined) of a 16 bit container.

11.6% waxing, crescent Moon with a DMK 37AUX273 and AstroDMx Capture for Linux

The 11.6% waxing, crescent Moon was imaged in broad daylight with a DMK 37AUX273 camera fitted with a 850nm IR pass filter attached to a Skywatcher Explorer 130 PDS 130mm, f/5 Newtonian, mounted on a Celestron AVX EQ, GOTO mount. A 5,000 frame SER file was captured using AstroDMx Capture for Linux running on a Fedora machine. The SER file was stacked and wavelet processed in Registax 5.1 running in Wine and the final image was post processed in the Gimp 2.10.

At full resolution, the camera maintained a frame rate of 52 fps, which allows the acquisition of large numbers of frames in a short period of time.

A solar prominence in H-alpha light with a DMK 37AUX273 and AstroDMx Capture for Linux

A Solarmax ll, 60, BF15 H-alpha scope was mounted on a Celestron AVX mount. A DMK 37AUX273 camera was fitted with the lens from a 2x Barlow and was placed at the focus of the scope. AstroDMx Capture for Linux was used to capture a 10,000 frame SER file exposed for a prominence at 160 fps with a ROI of 640 x 480. A 3000 frame SER file was captured, exposed for the disk. Autostakkert! 3.1 running in Wine was used to stack the best 15% of the prominence frames and 50% of the disk frames. Registax 5.1, running in Wine was used to wavelet process the resulting images. The two images were combined and post processed in the Gimp 2.10.

Again, the DMK 37AUX273 proved its worth as a high speed capture device for H-alpha solar imaging with a ROI.

Protecting a Newtonian primary mirror from dew and extraneous light.

The telescope featured here is a Skywatcher Explorer 130 PDS 130mm, f/5 imaging Newtonian. The back end of the primary mirror is protected by a black, rubberised sheet.

The bottom of the Newtonian reflector 

A problem with Newtonian reflectors is that in very cold weather, the back of the primary mirror can cooled by being exposed almost directly to the cold, ambient air. This can result in the front of the primary mirror dewing up even though it is at the bottom of a long telescope tube.
One way to ameliorate this problem is to use foam packing material, cut to size and attached to the sheet at the back of the primary mirror. Two layers of this material can be used (depending on thickness) and they can be attached using double sided sticky tape.

The foam insulation in place

This insulating foam protects the back of the primary mirror from the cold, ambient air. However, if  any stray light should happen to fall on the bottom of the scope, the white, semi-translucent foam will direct some of it outwards towards the edge of the telescope tube. This presents the danger that some unwanted light might make its way from the back of the scope onto the edge of the primary mirror. Sources of such light could be street lights, light from windows, street light reflected off building walls etc.
What is required is to cut a disk of matt black, 1mm styrene Plasicard and attach at least one sheet to the foam insulation and with a slightly greater diameter than the foam insulation. This serves to prevent extraneous light from falling onto the foam insulation, as well as adding another thin layer between the ambient air and the back of the primary mirror.

The black styrene Plasticard on top of the insulation foam

A finishing touch could be to attach a black shower cap to the bottom of the scope. In addition to extra darkening, this would trap another layer of air at the bottom of the scope to act as extra insulation. 1mm black Plasticard, A4 styrene sheets can be obtained from Amazon. 

M27 with AstroDMx Capture for Linux and a ZWO ASI178MC (USB3.0, 14 bit ADC) camera

A Skywatcher Explorer 130 PDS 130mm, f/5 Newtonian was mounted on a Celestron AVX EQ, GOTO mount. A ZWO ASI178MC (USB3.0, 14 bit ADC) camera was placed at the Newtonian focus.

ZWO ASI178MC

AstroDMx Capture for Linux was used to capture 45 x 55s Tiff files in RAW, undebayered format of M27. The best 40 images were stacked and debayered in Autostakkert! 3.10 running in Wine. The final image was post processed and scaled in the Gimp 2.10 and Neat image.

Having a 14 bit ADC means that this camera can yield 16,384 levels of brightness, compared with 4,096 levels with a 12 bit ADC camera. The data can either be saved to the lower bits of a 16 bit container, or to the upper bits, when captured by AstroDMx Capture for Linux.

M27

Larger view

High resolution 88% waning Moon images with AstroDMx Capture for Linux and a DMK 37AUX273 camera

A Skymax 127 Maksutov was mounted on a Celestron AVX, EQ, GOTO mount. An Imaging Source DMK 37AUX271 machine vision camera was placed at the prime focus. AstroDMx Capture for Linux was used to capture 8 overlapping, 2000 frame SER files of the 88% waning, gibbous Moon in High contrast and terminator areas, as well as the Copernicus/Kepler region.
(All running in Wine), Autostakkert! 3.10 was used to stack the best 80% of the SER file frames, Microsoft ICE was used to stitch the resulting images together and Registax 5.1 was used to wavelet process the resulting Mosaic. The resulting high resolution mosaic was post processed in the Gimp 2.10.
The scope was protected from the intrusive light from a nearby garden lamp by means of an occultation board which cast a shadow across the scope.

Occultation board

Copernicus and Kepler

Full size

High resolution Mosaic

Closer view

Full size pane of the Aristotelese, Eudoxus, Lacus Mortis, Hercules, Atlas, Posidonius region

Full size pane of the Theophilus, Cyrillus, Catharina, Fracastorius, Mare nectaris, Piccolomini region

Full size pane of the Tycho region

The DMK 37AUX273 can be considered to be an excellent Lunar and Solar imaging device. Seeing was too poor to gather worthwhile planetary images as Mars and Saturn were far too low in the sky. However, a test showed that high frame rates could be achieved capturing monochrome planetary data through this modest 5" Maksutov. Larger, planetary imaging scopes would cope even better.

H-alpha Sun with a DMK 37AUX273 and AstroDMx Capture for Linux

A DMK 37AUX273 camera was mounted at the prime focus of a Solarmax ll, 60, BF15 H-alpha scope, mounted on an iOptron Cube Pro, AZ GOTO mount.

AstroDMx Capture for Linux was used to capture two overlapping 1000 frame 8 bit SER files, which were Stacked in Autostakkert! 3.1, stitched in Microsoft ICE and wavelet processed in Registax 5.1, all running in Wine. The final image was post processed and colourised in the Gimp 2.10.

The Sun in H-alpha light

Active regions 2719 and 2720 are clearly visible as is a large filament.

Full size

The camera had sufficient dynamic range to be able to capture both disk and prominence details. The stitched image was duplicated and one image processed for the disk and the other processed for the prominences. The two images were then combined in the Gimp 2.1 to give the image presented here.

It is clear that this is a good camera for H-alpha solar imaging and was able to deliver over 60 fps whilst imaging at maximum resolution.

94% waxing Moon and the Ring nebula with AstroDMx Capture for Linux and a ZWO ASI178MC 14 bit camera

We are on the home straight towards the next release of AstroDMx Capture for Linux. These images were produced as part of the pre-release testing program.
The  ZWO ASI178MC is a camera with a 14 bit ADC and a back illuminated 6.4 MP Sony IMX178 CMOS sensor with 7.4 x 5 micro metre pixels which use STARVIS and EXMOR R technologies.

These technologies produce higher sensitivity and lower noise as well as reducing rolling shutter distortion. The back illumination avoids the internal circuitry in the sensor obstructing some of the light falling on the sensor before it reaches the photodiode. This allows for the reduction in size of the pixels and higher pixel counts on the sensor without increasingly the proportion of the light that is attenuated before it reaches the photodiode. The global shutter reset reduces the rolling shutter distortions that can occur if the subject moves (In astronomical imaging, the only movement should be due to seeing. However, some people image while the object drifts across the field of view or manually nudge the scope to keep the object in the field of view).

This test was done on a night with a low, 94% waxing Moon in the sky. This produced relatively poor seeing and a sky filled with Moon glow.

The ZWO ASI178MC camera was placed at the Newtonian focus of a Skywatcher, f/5, 130PDS Newtonian mounted on a Celestron AVX EQ, GOTO mount. Two overlapping 500 frame SER files were captured at full resolution (3096 x 2080). The best 95% of the frames were stacked in Autostakkert! 3.1 running in Wine. The resulting images were wavelet processed in Registax 5.1, and stitched into a single image using Microsoft ICE, both running in Wine. The final image was post processed in the Gimp 2.10.

Deep sky on a moonlit night

The ZWO ASI178 has a 14 bit ADC unlike many of the CMOS astronomical cameras which have 12 bit ADCs. This means that it can capture images with 16384 levels of brightness, compared with a 12 bit ADC which produces 4096 levels of brightness.
AstroDMx Capture for Linux saves the 14 bit data, mapped to the lower or the upper bits of a 16 bit container. This is still not up to the 16 bit ADCs of traditional CCD based astronomical cameras, but it is a substantial improvement on 12 bit devices.

With the bright Moon illuminating the sky, the ZWO ASI178MC in the same configuration was used to capture 40 x 40s exposures of the Ring nebula.

Screenshot of AstroDMx Capture for Linux capturing images of M57.

The display was using Gammalog, but could be changed to show more contrast if required, but as all that is usually required is to correctly position the object of interest, no further adjustments were made. It should be remembered that the display controls are non destructive, so do not affect the data being captured.

The best 90% of the images were stacked in Deep Sky Stacker running in Wine, and post processed in the Gimp 2.10.

Performance and real-time display are still being improved, but a release will not be far away.