Testing the 16 bit Atik Infinity camera with small telescopes

Testing the 16 bit Atik Infinity Deep Sky USB video camera

An Atik Infinity camera was kindly provided by Atik Cameras for these tests

The Atik Infinity

This camera is optimised for video astronomy. What this means in practice, is that when mounted on a telescope, the output from the camera can be displayed in near real time on the monitor of the computer that is running the Infinity capture software and to which the camera is attached. I tested the mono version of the camera, although a colour version is also available.
The camera is very sensitive and employs the SONY ICX825ALA CCD chip which has very low noise of just 6 electrons RMS and has a quantum efficiency of about 75% in the middle of the visible spectrum. It requires an external, 12 volts power supply and connects to the computer via USB 2.0.

The Atik Infinity has a 16 bit ADC, which is why this camera is fundamentally different from any other camera so far featured in this blog. An image with a 16 bit depth has a possible 65,536 levels of brightness whereas an 8 bit image only has 256 levels of brightness. The upshot of this difference is that it is much easier to saturate 8 bit images than it is to saturate 16 bit images. Consider a single pixel with a brightness value of 1 in an 8 bit image : If we were to sum 256 such images, then this pixel would be at maximum brightness; i.e. it would be saturated. However, if we had a pixel with a brightness value of 1 in a 16 bit image, we would be able to sum 65,536 such images before that pixel will saturate. This means that a 16 bit image will take longer to saturate as photons arrive at the sensor, and that there are a huge numbers of possible brightness states compared with an 8 bit image. The consequences of this are that when an image is stretched (i.e. the brightness values of the pixels are manipulated mathematically) it is possible to reveal subtle gradients in brightness in 16 bit images that would produce more crude steps in brightness gradients in an 8 bit image. With a linear stretch, each pixel is changed by the same factor, but with a non-linear stretch, mathematical functions can be used to increase, for example, faint parts of an image, whilst leaving the brighter parts untouched. 16 bit images are much better suited to this type of processing. The Infinity capture software has a selection of stretching functions, but sometimes parts of the live image appear to be saturated on the 8 bit display, whereas they are not saturated when the saved 16 bit image is stretched in a non-linear way.

The Infinity Capture software was used, but the image processing software provided by Atik was not used in these tests.
The Infinity software was launched, and set to Finder Mode. In this mode, the images are binned 4x4 and exposure is set to 1s. The object of interest is then moved into a suitable position on the screen. The image is noisy and low definition, but allows the object to be detected and positioned:

The software is then set to capture mode and an appropriate exposure (In the case of the Orion Nebula, 5s exposures were suitable with the equipment used) The image capture button was pressed and the images were allowed to stack on screen and then after a period of stacking (38 x 5s exposures in this case), the stacked image that has built up, now containing little noise is saved as a 16 bit file, usually a FITs file. This was a most convenient and pleasing way to capture images.

The Atik Infinity camera was placed at the Newtonian focus of an 150mm, f/5, Star Discovery, Newtonian. on an AZ GOTO mount to observe and capture images in these tests.

The Atik Infinity plus the Infinity capture software should be regarded as a Deep Sky astrovideography and image capture system.

Live stacking of the images allows the observer to see the image noise decrease as each image is added to the stack. Moreover, and most importantly, the Infinity capture software de-rotates the images as they are captured and added to the stack. This means that Alt-azimuth systems like the Star discovery system used here can be used for Deep Sky stacked image viewing and capture.

The captured exposures can be saved and at any time, used by the software in playback mode, which behaves exactly like the images coming in live from the camera. This means that functions such as flipping horizontally, and or vertically can be done later as the saved images are stacked. This can also be a useful feature for teaching purposes.

Images were collected of the Horsehead nebula and stacked on screen. The image was saved as a 16bit PNG file and post processed in Photoshop:

Horsehead Nebula

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Capturing and processing the 16 bit Fits images

Live view of an image that was saved:

The histogram can be changed on the fly for the displayed image, to reveal different parts of the structure


Using ESO,ESA, NASA Fits Liberator
Linear stretch of the image

With a linear stretch, the central part of the image is over exposed. However, this is a camera producing 16 bit Fits files, so there is a lot hidden in the bright parts of the image:

A non-linear stretch of the image (ArcSinh(ArcSinh(x))

Now, none of the image is overexposed.
The image can then be saved out as a 16 bit Tiff file:
The 16 bit Tiff image

This 16 bit Tiff image can then be further processed in Photoshop

The Processed 16 bit Tiff image

Finally, the image can be flipped and rotated if required, to give the required view, or the flipping could be done at capture time or in replay mode.

The final image:

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An Atik Infinity camera was placed at the Newtonian focus of an AZ, 150mm, f/5 Star Discovery , AZ, Newtonian. 15s exposures were set with image stacking. In both cases the stretching for viewing was set to MeanSD. This gave the best live views but is not applied to the saved images, which are saved as raw FITs files.

Live view of the Infinity software, stacking 15s exposures of M101

The resulting processed image of M101 
(Stack of 20x 15s exposures)

Live view of the Infinity software, stacking 15s exposures of M51

The resulting image of M51
(Stack of 20x 15s exposures)

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An Atik Infinity camera was placed at the Newtonian focus of a 150mm, f/5, Star Discovery AZ, GOTO Newtonian. Stacked images were captured as FITs files, processed in FITs Liberator and then Photoshop. Click on an image to get a larger view:

M81

M82

M97

M108

M1

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An Atik Infinity, 16 bit mono camera was placed at the prime focus of an 80mm, ED refractor. 6 x 30s exposures were stacked live and the resulting image was saved as a 16 bit FITs file. A non-linear stretch was applied in the ESO/ESA/NASA software FITs Liberator, and then further processing was done in Photoshop:

The Orion nebulae

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An Atik Infinity camera was placed at the Newtonian focus of a 150mm, f/5, Star Discovery, AZ Newtonian. 20x 15s exposures  of the Black-Eye Galaxy were stacked live and then saved as a FITs file. The image was non-linearly processed in the ESO, ESA, NASA Fits Liberator Software, and Photoshop:

The Black-Eye galaxy

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The Atik Infinity is an easy camera to use. Together, the Infinity camera and the Infinity software provide a powerful imaging system, that even with small scopes on AZ mounts, can produce good deep sky images. However, the high sensitivity of the camera, in conjunction with the live stacking of captured images, makes the Infinity a delightful tool for individual or shared observing and makes it an ideal camera for outreach activities.
There is also a colour version of the Atik Infinity, which was not tested here.

I have published a review of this camera in Popular Astronomy 3, pp 33-35

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A Cheap, 1.3 Mp USB board camera, a possible starter camera for outreach, observation and an introduction to imaging

The Camera, an ELP, 1.3 Mp, CMOS, USB board camera is available at the time of writing, for £29-99p on Amazon.

Camera re-mounted in a project box

It has been tested here using SharpCap 7 capture software and a 150mm, f/5, AZ Star Discovery Newtonian. The camera was placed at the Newtonian focus of the telescope, and 500 frame AVIs were captured at full resolution of 1280 x 960 pixels. Registax was unable to read the AVIs, which were read into VirtualDub and re-saved as uncompressed AVIs (this does not affect any compression that may be imposed by the camera's firmware).
The first thing to note is that the camera does deliver some compression in both YUYV and MPEG formats, with framerates of 9fps and 15fps respectively. This having been said, the compression is not as severe as in some webcams, and delivers pleasing live views suitable for shared observing. So far, the camera has been tested on the Moon, but not on any planets.

Live Views using SharpCap

The terminator was imaged as a Mosaic of 4 overlapping images of the 55%, waxing, gibbous Moon, derived from 500 frame AVIs.

Terminator of the 55%, waxing, gibbous Moon

Another night, 8 overlapping AVIs of the 84%, waxing, gibbous Moon were captured and the resulting images combined into a mosaic.

84%, waxing, gibbous Moon

Although some compression is evident in these images, it is not sufficient to prevent the capturing of pleasing images, and from producing live images of the Moon that are suitable for shared observing and outreach.

The Orion nebula with a LN300 video camera

A LN300 video camera, fitted with an IR/UV cut filter was placed at the Newtonian focus of a Star Discovery, f/5, 150mm Newtonian and 150 frame AVIs were captured at 4 different exposures. The AVIs were stacked in Registax and the resulting images were derotated and stacked in Deep Sky Stacker. The resulting image was post processed in Photoshop:

An animation was made of the separate exposures and the final image to show the information that can be extracted from the images when combined.

M51 and C/2013 U10 (Catalina) with an LN300 video camera and a 150mm AZ Newtonian

The LN300 video camera fitted with a light pollution filter was placed at the Newtonian focus of an f/5, 150mm Star Discovery Newtonian on its AZ GOTO mount. The camera was set to 512x exposure and 44 images of M51 were captured using SharpCap, via a USB capture card. The images were derotated and stacked in Deep Sky Stacker and post processed in Photoshop:

On January16, 100 images of Comet Catalina C/2013 U10 were captured with the camera set to 256x exposure.20 of the images were derotated and stacked in Deep Sky Stacker and post processed in Photoshop:

When all 100 images were derotated and stacked, the movement of the comet was clearly visible:

The Swan nebula with a LN300 video camera and a 150mm f/5 AZ Newtonian

A LN300 Video camera fitted with a UV/IR and a Light pollution filter was placed at the Newtonian focus of an f/5, 150P star Discovery AZ GOTO Newtonian telescope. 175 x 10.24s exposures were captured of M17 using SharpCap. 50 x 10.24s dark-frames were also captured. The best 85 frames were de-rotated, dark-frame corrected and stacked with Deep Sky Stacker:

The Omega nebula, M17

 Live view of the nebula in the SharpCap capture software

The dumbbell and crescent nebulae with an LN300 video camera and a Star Discovery 150mm Newtonian

An LN300 video camera fitted with a UV/IR cut filter and a light pollution filter was placed at the Newtonian focus of a Star Discovery, f/5, 150P Newtonian on a Star Discovery AZ GOTO mount.
The camera was set to 10.24s exposures and SharpCap was used to capture unique frames.
140 x 10.24s frames were captured of M27 and the best 84 frames were derotated and stacked in Deep sky Stacker. The resulting image was post processed in Photoshop and Aspect ratio corrected in Nicola Mackin's Aspect Ratio Corrector software.

M27

48 x 10.24s frames of the Crescent Nebula, NGC6888 were captured, derotated and stacked in Deep Sky Stacker. The resulting image was post processed in Photoshop and Aspect ratio corrected in Nicola Mackin's Aspect Ratio Corrector software.

Live view of M27 in the SharpCap program

NGC6888

Desaturated image of the Crescent Nebula

This imaging was done under the glare of a street light within 3m of the telescope. The scope was shaded from direct light from the street light by using an occultation board mounted on a photographic tripod.

The dark shadow cast by the occultation board can be seen cutting off the direct light from the mouth of the telescope. This photograph was taken, handheld in the light from the street light.

This shows the problem that is overcome by the use of the occultation board. The view is from behind a small Newtonian from slightly different angles, showing the street light and its occultation:

In this location the skies are dark with the main problem being direct light from street lights and sometimes security lights.

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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