M13 with a 150P Newtonian and an LN300 video camera

A LN300 video camera was placed at the Newtonian focus of a 150P Star Discovery, AZ GOTO Newtonian. The camera was connected to a Windows 10 laptop via a Digital Climax VCap303 capture card. 100 x 2.56s frames were captured of M13 using SharpCap. 100 x 2.56s dark-frames were also captured.The best 90% of frames were dark-frame corrected, registered, derotated and stacked in Deep Sky Stacker. The aspect ratio of the final image was corrected in Nicola Mackin's Aspect Ratio Corrector software. The resulting image was post processed in Photoshop.
A street light shines down onto the spot where I sometimes observe. An occultation board mounted on a photographic tripod shades the scope from the glare of the light and prevents light from the street light directly entering the top of the scope tube and causing internal reflections that ruin the exposures.

M13

The occultation board is simply constructed with a female photographic thread at the base

The occultation board mounted on a tripod showing the offending street light

The occultation board in action, shading the scope from direct street lighting

If the sky is dark, the main objective is to prevent direct light from the street light from entering the top of the telescope tube at an oblique angle. This is the main problem, whilst other ambient light is much less of a problem. When this photograph was taken, there was also a first quarter Moon low in the sky.

M57 with the LN300 video camera and the 150mm Newtonian on a Star Discovery AZ GOTO mount

The LN300 video camera was placed at the Newtonian focus of the Star Discovery 150P, f/5 Newtonian. The camera was connected to a Windows 10 laptop via a Digital Climax VCap303 capture card. 300 x 5s exposures of M57 were captured using SharpCap. 100 x 5s dark-frames were also captured. The best 240 exposures (20 min total exposure) were dark-frame corrected, registered, derotated and stacked in Deep Sky Stacker. The resulting image was post processed in Photoshop:

M57

The live screen view was pleasing and shows that this is very suitable for viewing and sharing the view as an electronic, deep sky eyepiece.

Live View whilst capturing in SharpCap

M27 with 5s video frame exposures with a LN30 video camera and a 150 mm, f/5 Newtonian

The LN300 video camera was fitted with a Baader UV/IR rejection filter and placed at the Newtonian focus of an AZ GOTO, 150 mm, f/5. Newtonian. The camera was set to SENS OFF (frame accumulation) and LENS shutter exposure of 256 x 1/50s = 5.12s. The camera was connected to a Windows 10 laptop via a Digital Climax VCap303 capture card. SharpCap was used to capture 100 frames, one frame every 5s. Similarly, 100 x 5s dark-frames were captured. The best 90 frames were registered, derotated and stacked in Deep Sky Stacker, post processed in Photoshop and finally aspect ratio corrected in Nicola Mackin's Aspect Ratio Corrector software:

Live view of the computer screen with SharpCap

The live view was very pleasing and would be good for star parties or sharing viewing.

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Long exposures with the LN300 frame-integrating video camera

The Star Discovery AZ, GOTO mount with a Star Discovery 150 mm, f/5 Newtonian was use with the LN300 video camera fitted with a Baader UV/IR rejection filter to image M17.
In this experiment the SENS was turned off so that the camera was not accumulating frames. The AGC was set to low and the LENS control which controls shutter exposure, was set to x 256 of the normal shutter exposure of 1/50s per half frame. This gives an exposure of 5.12s. It should be noted that the shutter speed function changes by factors of 2 in the same way to that of the SENS frame accumulation. This camera can go to 20s with a factor of x 1024.
The camera was connected to a Windows 10 computer via a Digital Climax VCap303 capture card.
SharpCap was used to capture frames from the camera at a rate of one frame per 5 seconds and the frames were saved as PNG files. 100 x 5s frames were captured along with 50 x dark-frames.
The frames were dark-frame corrected, de-rotated and stacked in Deep Sky Stacker, stacking the best 80% of the frames.
The resulting image was post processed in Photoshop:

M17

In the absence of any user documentation, the functions of the camera are having to be deduced by experiment.
Using the settings above, the camera produced a very pleasing live display which will be very useful for star parties when a small video monitor will be used to display the image rather than a computer.

First light for a low cost frame-accumulating video camera and a Star Discovery AZ GOTO, 150 mm, f/5 Newtonian

The camera is a low cost (about £45) LN300, frame accumulating video camera producing composite video output.

LN300 video camera

The camera is seen here fitted with a scope adapter and a Baader UV/IR cut filter.

Five buttons on the back control the camera functions via an On Screen Display

The camera was connected to a laptop via a Climax Digital VCap303 capture card as shown in a previous blog. 50 x 5s integrated frames of M17 were captured using SharpCap capture software. I used similar setting to those I would have used with a Mintron with SENS = 256. The software was set to capture a frame every 5 seconds and to save the frames as PNGs.
The LN300 camera was placed at the Newtonian focus of a Star Discovery AZ, 150 mm, f/5 Newtonian system:

150 mm, f/5 Star Discovery, f/5 Newtonian

The best 40 frames were stacked in Deep Sky Stacker, which derotates before it stacks the images. This is essential with an AZ mount. The resulting 16 bit Tiff file was post processed in Photoshop:

M17

Diffraction spikes, accentuated by the sturdy spider can be seen in the image. I rather like diffraction spikes, so the spider is no problem to me.

The LN300 camera has some fundamentally different features to the Mintrons and Samsung frame-accumulating video cameras. One such feature is the ability to slow the shutter speed below the standard 1/50s per half frame. It is not immediately clear how this actually works, but seems to increase the exposure as would be expected, even when the SENS (frame accumulation) is turned off. This is a feature that will be explored in future experiments, but the implication is that there is a distinction between the frame accumulation (In Steve Massey's terminology) and length of individual frame integration.
This has been a successful first light for the new, portable system.

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A camera needs a lens. I this case, a 150mm f/5 Newtonian

I have obtained an ideal portable system for use with deep sky astrovideography in the field. The new Skywatcher Star Discovery mount with Synscan 4 and Freedom find (allowing manual movement of the scope without losing alignment. The scope with the mount is the 150P f/5 Newtonian. The mount is a more robust version of the AZ Synscan mount that carries the 130mm Newtonian or the 127mm Maksutov. The quick release knob allows for easy movement of the scope in altitude:

The collimation screws are hidden behind a cap so it is hard to accidentally change collimation. The scope arrived in perfect collimation as checked by two laser collimator systems working on different principles.

The spider is thick and will most likely produce prominent diffraction spikes on the brighter stars.

This is the portable system that I shall be using with a frame integrating video camera to image deep sky objects in the field. Being an altazimuth mount is not a problem as each frame integrated exposure will be short enough for there to be no image rotation within an exposure, and between exposure image rotation can be dealt with by Deep Sky Stacker during the stacking process.

First light was achieved by putting a DMK camera at the Newtonian focus. Images of the Ring nebula and the Swan nebula were obtained:

Ring nebula with a DMK

Swan nebula with a DMK

The next day, a Mintron 22S85HC-EX Mintron monochrome frame-integrating video camera with a 1/2" sensor was placed at the Newtonian focus and DVD was recorded at high quality of M17, the Swan nebula and M27, the Dumbbell nebula and M20, the Trifid nebula. The individual BMP frames were extracted from the DVD VOB (Video object) files using Ian Davies's Vob Frame Extractor set to extract a unique frame every 256th frame from the VOB and save the BMPs. The BMPs were stacked in Deep Sky Stacker which derotates the image before stacking them. The resulting 16 bitTiff file was post processed in Photoshop and then the aspect ratio was corrected using Nicola Mackin's Aspect Ratio Corrector software:

M17 with a Mintron

The larger sensor of the Mintron produces a wider field of view

M27 with a Mintron

Images of M27 stacked in Registax with no derotation, clearly show image rotation. This is why it is important to stack with Deep Sky Stacker when using an AZ mount.

M20, the Trifid nebula

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