Sunday, 8 December 2019

Further maintenance release of AstroDMx Capture for Linux, version 0.64.4

Nicola has released a further maintenance release of AstroDMx Capture for Linux.
This is version, 0.64.4. and was needed to resolve a remaining issue.

Maintenance release of AstroDMx Capture for Linux, version 0.64.3

Nicola has released a maintenance release of AstroDMx Capture for Linux.
This is version 0.64.3
This was necessary because of a fault in the latest QHY SDK which rendered some QHY cameras unstable and likely to drop their connection.

It is hoped that a new version of AstroDMx Capture for Linux, fully supporting the SVBONY SV305 camera will soon be released, when SVBONY have fixed their Linux SDK for 12 bit (16 bit) support.

Tests with the latest version of Elementary OS, 5.1, Hera, show that AstroDMx Capture for Linux now installs and runs properly from the menus. With earlier versions of the OS, the program would only run from the command line.

Friday, 22 November 2019

Stacking multiple exposures of the Moon with a Bridge camera

A Panasonic Lumix DMC-FZ72 Bridge camera was fitted with a fairly high speed SD card (32 GB SanDisk Extreme 90/MB/s Class 10, U3, V30).

The camera was set to ISO 100 and was mounted on a static tripod. Lunar images were captured in burst mode (3 images per burst) at 4 different exposures: 60 exposures at 1/1000s, 60 exposures at 1/800s, 114 exposures at 1/640s and 42 exposures at 1/500s. Giving a total of 276 images.

The images were precisely cropped in Astrocrop to centre and register them before stacking.

All of the cropped images were stacked in Autostakkert! 3. The resulting image was wavelet processed in Registax 5.1 and post processed in the Gimp 2.10.

The SD card showed noticeably faster transfer rates when capturing images than with the original class 4 card.

It is intended to repeat the experiment with even faster cards to determine any advantage of using very fast cards when capturing lunar data in this way. The aim is to capture large numbers of images before image rotation becomes an issue.

99.2% Moon

Closer view

Sunday, 17 November 2019

A new version of AstroDMx Capture for Linux

Nicola has just released version 0.64.1 of AstroDMx Capture for Linux, including the Raspberry Pi version.
The software can be downloaded from

Work has now started on the implementation of the SVBONY SV305 camera in AstroDMx Capture for Linux.

Changelog for version 0.64.1

Added DSLR camera support.

Significant performance optimisations.

Added display performance options.

Significant preview display improvements.

Added hardware accelerated preview display mode.

Mouse to pan around the preview display (OpenGL mode).

UI Tweaks and optimisations.

Camera controls, such as gain or gamma, can now be made during long exposures without cancelling the previous control.

Values can now be typed into the display control UI.

Significant improvements to the way that the application stores settings.

The main camera controls can now be hidden.

Improvements for failed exposures handling.

Saturation and Reticle colours are now stored.

Display controls / transforms no longer have an affect on frame rates.

Added auto USB bandwidth and USB speed functions for ZWO cameras.

Fixed possible font issues on some Linux distributions.

The main control area size now stored.

Added SER time stamps.

Added mouse over help to many UI controls.

Improved function to scale the live preview.

Saturation and reticle and now be changed in real-time.

Colour space and resolution can now be changed during long exposures.

Fixed a problem that sometimes caused the main controls to jump position.

QHY SDK updated to version 6.0.5

ZWO SDK updated to version 1.14.0715

Other bug fixes and improvements.

Temporarily removed the reset all controls reset function.

Saturday, 2 November 2019

Two generations of TRUST webcams head-to-head as solar-system astronomical imagers

The two cameras to be compared are the TRUST WB-5400 megapixel webcam that I obtained early 2007 and the TRUST Spotlight Pro webcam that arrived today.

I have chosen these two cameras because they are from the same manufacturer and both have hardware resolutions of 1280 x 1024, which is a very suitable resolution for Lunar and solar imaging, consistent with reasonable frame rates. Back in 2007 I produced very satisfactory lunar images  with the WB 5400 as can be seen on the QCUIAG website in the megapixel imaging section. I also published an article in Astronomy Now the following year:

The high resolution webcam revolution: A new generation of megapixel webcams is producing high-resolution astronomical images from CMOS chips. S.J. Wainwright 2008, Astronomy Now, 3, 80-81.

The WB-5400 is no longer available new but at the time of writing, the Spotlight Pro is available at about a £13 - £18 price point in outlets such as Amazon UK and Currys PC World.
Both cameras have CMOS sensors with native hardware resolutions of 1280 x 1024.
In addition, a telescope (Mogg) adapter can be obtained from Amazon UK for £4 - £8.

Preparing the cameras for astronomical imaging

Both are easy to modify. The cases are easy to open and the lenses are standard M12 threaded, which screw right out. The Spotlight Pro has six LEDs which were removed by clipping their long legs. This removes an unwanted component and creates six ventilation holes that do not allow dust access to the sensor.
A standard Mogg telescope adapter can be screwed into the lens threads and the camera is ready for imaging.

Spotlight Pro


The following tests were done using a Skymax 127 Maksutov and an 80% waxing, gibbous Moon.

The tests involved:

a) Imaging the Moon with the same telescope and different cameras.

b) Looking for evidence of vignetting.

c) Looking for evidence of compression artefacts.

d) Considering the quality of the images obtained

AstroDMx Capture for Linux was used with both cameras and AstroVideo for Windows was also used with the the WB-5400, which was never made fully compatible with Linux.
The WB-5400 has a WDM Windows driver that provides even more controls than the new Spotlight Pro.) AVIs were captured by both systems and also, the WB-5400 was tested with its minimal controls in Linux).

However, the plot thickens: I have two TRUST WB-5400 cameras dating back to 2007. On probing the kernel modules, the two (apparently identical) cameras have two different sensors. One is a Micron MT9M111 sensor and the other contains a Silicon Optronics SOI968 sensor. They are both 1.3 M pixel CMOS sensors and are controlled fully by the WDM driver.

With a standard Linux kernel, the camera with the Silicon Optronics sensor offers a working gain control in AstroDMx Capture for Linux whereas the camera with the Micron sensor does not offer gain control. Both cameras offer a working gamma control, but the Brightness and contrast controls do not work.

AstroVideo is Windows capture software that I worked on with Bev Ewen-Smith of COAA at the turn of the century. Bev did all of the coding and I did testing and debugging as well as specifications.
AstroVideo was initially developed for off-chip video integration by summing hundreds and thousands of video frames from low-light surveillance cameras into 32 bit Fits files. The software utilises track and stack of the movement of objects on the sensor and actually synthesises long exposures by summing many short exposures. Some of the results obtained can be seen on the QCUIAG website. If you use Windows and wish to use legacy cameras or video cameras via capture cards, then AstroVideo is the Windows software to use. In these experiments, we used AstroVideo to control the TRUST WB-5400 camera, and to capture AVIs from it with full controls.

The problem with using modern CMOS webcams for Lunar and planetary imaging are mainly threefold:

1) Many small, HD CMOS sensors are intended to work with small lenses very close to the chip and they display various degrees of pixel vignetting, that must be corrected by flat fielding.

TRUST-WB5400 with and without flatfield, captured with AstroDMx Capture for Linux
No evidence of vignetting with this 2007 camera

TRUST Spotlight Pro with and without flatfield, captured with AstroDMx Capture for Linux
Vignetting, corrected with flatfield

2) Many CMOS webcams compress the video stream and give no options for uncompressed or lossless compressed video streams. I suppose that this is OK for video conferencing in HD, but is absolutely useless for imaging the Moon etc, where compression artefacts render the resulting image useless.

Screenshot of AstroDMx Capture for Linux capturing data from the TRUST Spotlight Pro
Screenshot of AstroDMx Capture for Linux capturing data from the TRUST Spotlight Pro

TRUST Spotlight Pro
Clavius Region

Screenshot of AstroDMx Capture for Linux capturing data from the TRUST Spotlight Pro

TRUST Spotlight Pro
Sinus Iridum region

Very little compression was evident in the Spotlight Pro, with virtually none in the WB-5400.

Clavius region captured with AstroDMx Capture for Linux with minimal controls

Clavius region captured with AstroVideo for Windows with full controls

3) Many CMOS webcams offer very little control over the video stream, which means that notwithstanding points 1 and 2 above, it is difficult, or impossible, to achieve satisfactory exposure across the whole image.

AstroVideo screenshot showing the controls of the WB-5400

The conclusion drawn is that whilst both cameras produced acceptable images, the old WB-5400 was superior on two counts:

  1. The WB-5400 displayed no pixel vignetting.
  2. The WB-5400 displayed no noticeable compression.
Modern webcams almost invariably use compression to speed up the video for video conferencing. They also use small sensors, which are subject to pixel vignetting. Both of these facts are unfortunate for the use of these devices for astronomical imaging.

As devices for outreach, or as an introduction to lunar and planetary imaging, cameras such as the modern TRUST Spotlight Pro are quite suitable.

Monday, 28 October 2019

Ethernet over mains remote imaging with AstroDMx Capture for Linux and a Canon EOS 4000D DSLR

An experiment with remote DSLR imaging with Ethernet over mains via powerline ethernet adapters.

Our observatory is 20m from the house and we routinely run an extension cable out to the observatory to power the mount and an imaging laptop.

We used a Tenda P200 kit pair of powerline Ethernet adapters. The adapters each have a UK plug and an Ethernet socket. One adapter was plugged into the mains in the house near to the router and an Ethernet cable was connected between the adapter and the router. The other adapter was connected to the end of the extension lead in the observatory and an Ethernet cable was connected between the adapter and the imaging laptop in the observatory, which was running Ubuntu Linux 19.10. This gave Ethernet access to the observatory laptop. The observatory laptop was covered by a plastic printer cover to prevent condensation from forming on the keyboard.

Powerline Ethernet adaptor

Nicola configured the observatory computer was with a fixed IP address within the same subnet as the main network. The observatory computer was running a VNC server that ships with the OS, which provided a mechanism to access the remote computer's desktop and fully control AstroDMx Capture. The observatory computer was setup as shown in the following screenshot.

A laptop in the house running Fedora Linux was then able to access the observatory computer's desktop by using a standard VNC client application and fully control the desktop of the observatory computer. This allowed the computer in the house to see the live preview and remotely operate the controls of AstroDMx Capture for Linux.

A motor-focuser-adapted Bresser Messier AR 102xs f/4.5 ED refractor was mounted on the HEQ5 Synscan GOTO mount in the observatory. Using a 2" adapter, fitted with a light-pollution filter, a Canon EOS 4000D DSLR was placed at the prime focus of the refractor. The DSLR was USB tethered to the observatory Ubuntu laptop.

30 x 90s exposures at ISO 6400 were captured of M31 with matching dark-frames and 22 x 90s exposures were captured of NGC7789, Caroline Herschel's White Rose cluster in Casseopeia.
The camera RAW images were stacked in Deep Sky Stacker and post processed in the Gimp 2.10.

Screenshot of the Fedora laptop controlling AstroDMx Capture for Linux on the observatory Ubuntu computer, capturing data on the Andromeda Galaxy

Screenshot of the Fedora Laptop controlling AstroDMx Capture for Linux on the observatory Ubuntu computer, Capturing data on the White Rose Cluster

The Andromeda Galaxy

NGC7789 The White Rose cluster

On a cold night, this system only required occasional visits to the observatory to check on things.

Sunday, 20 October 2019

Python and the Moon

A motor-focuser-adapted Bresser Messier AR 102xs f/4.5 ED refractor was placed on a Celestron AVx GOTO mount, and a DFK 21AU04.AS camera fitted with a 2.5x Barlow was placed at the prime focus. 1500-frame AVIs were captured of ten overlapping regions, to cover the terminator of the 64.2% waning Moon. A short Python, with OpenCV3, program running in the Thonny IDE, on an Ubuntu 18.04 laptop, was used to control the camera and capture the AVIs captured using a lossless HFYU Hufman compression codec. VirtualDub was used to decompress and re-save the AVIs. The best 80% of the frames (1200) were stacked in Autostakkert!, precisely cropped to 640 x 480 in the Gimp 2.10, stitched in Microsoft ice and Post processed in the Gimp.

Screenshot with the preview flipped into the correct orientation and enlarged to facilitate focusing

Screenshot of the python program capturing the 1500-frame AVI

An individual pane of the Clavius region

Ten-pane mosaic of the terminator of the 64.2% waning Moon

Full size

Python with OpenCV is a powerful system for machine vision, and can be used to build capture systems. The code is not presented here as it is a work in progress, and is part of another project. Eventually, it is likely that the code will be presented here some time in the future.

Tuesday, 15 October 2019

The SVBONY SV305... Where do I stand with this new camera

The previous posts have indicated that the SV305 is a very capable camera with no apparent issues. When we finally get a Linux SDK it will be available to many more users, and at the current price point of about £120, it is very good value. So far, all of our tests have been with Windows, which limits our ability to fully demonstrate the strengths of the camera. Nevertheless, I have been very encouraged with the results in both 8 bit and 12 bit (16 bit) modes. It has, with relatively small, fast scopes, been capable of imaging deep sky objects as well as the Moon.

A Skywatcher Explorer 130 PDS 130mm, f/5 Newtonian was mounted on a Celestron AVX GOTO mount. An SVBONY SV305 camera was placed at the Newtonian focus and 30 x 45s exposure were captured. The best 28 images were stacked in Autostakkert!3. The resulting image was post processed in the Gimp 2.10 and FastStone.

M17 the Swan or Omega nebula

Stack of 36 x 22.6s exposures of M27 using a 102mm, f/4.5 refractor and an SVBONY SV305 camera.

Who is this camera aimed at?
The SV305 has no guiding port so it is purely for imaging. There is a plethora of cameras that have guiding ports, but most people buying a low cost camera as an introduction to astronomical imaging will not be doing auto-guiding. They will be imaging the planets and Moon as well as many of the brighter deep sky objects. Previous posts have shown that the SV305 delivers the results that an imager would be looking for.

The camera sports a 6.5mm, SONY IMX290 backlit sensor of 2M pixels (1920 x 1080) with exposures ranging from 1 ms to 30 min. The camera also sports a 128MB DDR image buffer unlike some other low cost cameras.

The only unfortunate thing about this camera is it's designation: SV305. The SV305 IS NOT a descendant of the SV105 and SV205 cameras. It is a completely new camera that is built to high standards and does not suffer any of the limitations of these other two devices. (The SV105 was a cheap camera suffering from pixel vignetting, that, as covered in previous posts, could be corrected by Flat fields, a camera that is a good absolute starter device. The SV205 was conceptually flawed with an 8Mp sensor and still suffered from the pixel vignetting of the SV105).

The SV305 is a completely new and unrelated device that I have found no issues with. This camera seems to have no problems and is a pleasure to use. Whatever camera you are moving up from, you should not be worried about investing in an SV305; an excellent camera at a good price point. Of course, as with any purchase, Caviat emptor applies, but so far, the SV305 seems to be a safe bet. I am looking forward to using this camera during the winter observing/imaging season.

We are also looking forward to implementing the SV305 in Linux and MacOS.

Saturday, 14 September 2019

M13 in a bright, moonlit sky with a Bresser Messier AR 102xs f/4.5 refractor and an SVBONY SV305 camera

A motor-focuser adapted Bresser Messier AR 102xs f/4.5 refractor (see previous blog post) was placed on an HEQ5 GOTO mount, and an SV305 camera was placed at the prime focus.
30 x 15s exposures were captured of M13 with matching dark-frames. The best 27 frames were dark-frame corrected and stacked in Autostakkert!3. The resulting image was post-processed in the Gimp 2.10.

Click on the image to get closer views.

M13 with an SV305

Notwithstanding the 99.7% Moon in the sky, the SV305 performed well, as did the motor focuser.

Wednesday, 11 September 2019

Motor focusing the Bresser Messier AR 102xs f/4.5 refractor

The Bresser Messier AR 102xs f/4.5 refractor is a fast, ED, short tube refractor with a novel zero image shift hex-focus system with a helical gear rack, reducing backlash in the focuser. The focusing system is very good for visual observing but falls short for imaging. Whilst turning the focusing knobs the image rapidly goes through focus and it takes a long time to achieve a satisfactory focus. There is an optional slow motion focuser that can be retrofitted. However, I was unable to get it to work properly and after many attempts, plus speaking to the distributor, it was decided to return the slow motion system. I do not know what the problem was, maybe with my scope or with the focuser. I decided that if this scope is to be used for imaging, the purpose for which it was intended, I would have to attempt to fit a motor focuser, although it was not immediately obvious how this could be done, as the underside of the focuser is by no means standard.
I decided to use a Skywatcher auto-focuser and to modify the bracket with which it attaches to the scope. The modification involved drilling a hole in the bracket large enough to accommodate the large, black locking knob on the base of the scope and to use a large washer to distribute the force. This worked fine and the two photographs below show the motor focuser attached to the scope. Two strips of double-sided tape were used either side of the black knob between the bracket and the scope before the black knob was tightened down, to help resist turning of the assembly during focusing.
With the motor focuser in place, there is no need to lock the focuser once focus is achieved as this is done by the friction of the motor.

The system works, and now it remains to be seen how easily focus can be achieved with a camera attached. The advantage of this system is that the modification is to the motor focuser bracket and not to the scope. The first tests will probably be done with the SVBONY SV305 camera.