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.

Sunday, 8 September 2019

First deep-sky with the SVBONY SV305 camera

Although there was a 63% waxing Moon in the sky, the Moon was quite low during this lunation. A globular cluster was considered to be the best class of deep-sky objects on which to make the test.
Until Nicola is given the Linux and macOS SDKs with which to implement the SV305 in Linux and macOS, we have used SharpCap in a fresh build of Windows 10 with which to capture data.
An ED f/5.5, 80mm refractor was mounted on a Celestron AVX GOTO mount and the SV305 camera was placed at the prime focus.
80 x 20.3s exposures of the globular cluster M2 were captured in RAW12 as 16 bit Tiffs along with 30 matching dark-frames at maximum resolution of 1920 x 1080.
The best 72 frames were dark-frame corrected and stacked in Autostakkert!3 to debayer the Tiffs, giving a total exposure time of just 24.36 minutes. The final image was back-cropped to 1920 x 1080 and post processed in the Gimp 2.10.

Click on the image to get a closer view


Notwithstanding the bright sky due to moon sky-glow, the SV305 performed well and produced a pleasing image of M2, demonstrating that this camera has the capability of capturing deep sky images.

Saturday, 7 September 2019

First tests on the SVBONY SV305 astronomy camera

SV305 a new Astronomy camera

We were supplied with a SVBONY SV305 camera by the company and have started testing this astronomy camera, prior to implementing it in AstroDMx Capture for Linux and macOS
This is a home grown, full-fledged, one shot colour astronomy camera from SVBONY. It uses the back-illuminated Sony IMX290 6.5mm (diagonal) CMOS sensor with 2.9┬Ám square pixels. Like a number of astronomy cameras available at the moment, it features 128MB of DDR ll RAM as an image buffer. It has a USB2.0 computer interface. It is a 2Mp camera giving a maximum resolution of 1920 x 1080. It supports arbitraty size ROI and has a 12bit ADC. The camera outputs 8 bit and 12 bit RAW data. The exposure range is from 1 ms to a respectable 30 minutes.

Unboxing the SV305

The SV305 arrived in a sturdy box containing the camera, a 1.25" , filter-threaded adapter with a dust cap, a C/CS adapter that allows the attachment of a C/CS lens if required, a 1.5m USB 2.0 lead with a short flyout lead with a USB connector for extra power if required.

The camera housing

The SV305 is housed in a well built, aluminium case of familiar design, reminiscent of earlier SVBONY electronic eyepiece cameras distinguishing this camera at a glance, from similar cameras from other manufacturers. The camera is uncooled, but the metal case should facilitate excess heat dissipation.
The IMX290 CMOS protector is protected behind an optical glass window. The overall look and feel is of a well built, sturdy camera.

First Light

The first tests were made with a freshly built Windows 10 laptop running SharpCap capture software. Linux and macOS implementation will be completed for AstroDMx Capture as soon as we are provided with SDKs.
The SV305 was placed at the Cassegrain focus of a Skymax 127 Maksutov telescope mounted on a Celestron AVX GOTO mount.
Four overlapping regions of the 46.7% waxing, crescent Moon were imaged at maximum resolution 1920 x 1080. Four, 5000-frame SER files were captured. The best 50% of the frames in the SER files were stacked in Autostakkert! 3. The resulting images were wavelet processed in Registax 5.1, cropped back to exactly 1920 x 1080 in the Gimp 2.10, stitched together into a 4-pane mosaic in Microsoft ICE and post processed in the Gimp 2.10.

4-Pane Mosaic lunar image

Full size

First impressions of the SVBONY SV305 are very favourable. The camera behaved perfectly during the imaging session and was a pleasure to use. Further testing will involve planetary imaging, and, when the Moon is out of the way, Deep-Sky Imaging. The results will be posted here when they are obtained and news of implementation in Linux and macOS will be posted as soon as it is done.