Advances in colour Mintron deep-sky imaging

The Shape of things to come.

I am working on a new colour Mintron camera with Mintron Enterprise Co., Ltd. and have some preliminary results to show. This is the 72S85H-EX-SW-OMEGA colour 1/2" chip, deep-sky Super Wide field, low amp-glow Mintron frame-accumulating video camera..
I have tested this experimental camera with a variety of telescopes and present some results here:

M42/3 with an f/5 130mm Celestron Nextstar SLT Newtonian.



M42/3 with an f/5 Kson 80mm apochromatic refractor

In both cases the image was made by combining three images: one exposed for the outer, fainter nebulosity (256 frame accumulation), a second exposed to an intermediate level (64 frame accumulation) for the nebulosity immediately surrounding the central, trapezium area, and a third exposed for the central, bright, trapezium part of the nebula (8 frames accumulation).

M43 with an f/4.8 10" newtonian



The Flame nebula in Orion with an f/4.8 10" Newtonian



The Running Man nebula in Orion with an f/4.8 10" Newtonian


The blue reflection nebula has shown up quite well in the final image.


M1 The Crab nebula with a 10" f/4.8 Newtonian and a 0.5 focal reducer

M13 with a 10" f/4.8 Newtonian and a 0.5 focal reducer

M57 with a 10" f/4.8 Newtonian and a 0.5 focal reducer

M27 with a 10" f/4.8 Newtonian and a o.5 focal reducer

Telescope Planet Mintrons

Remember that a monochrome camera is always going to be much more sensitive than a colour camera.
To obtain satisfactory colour images you must have a fast scope, and the bigger the aperture the better.



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Article in Astronomy Now on extracting images from DVD recordings without using a capture card and with no loss of quality

Advances in Deep Sky Video Astronomy

Ian Davies and I have published an article in the December 2009 issue of Astronomy Now magazine in which we show how to capture images directly from DVD recordings without the use of a capture card and with no loss of quality.

If, as I do, you record your Mintron video stream to DVD for future viewing and subsequent image capture, then this article is for you.

All you need is a computer with a DVD drive and our new freeware software.

Full details including how to get the software are in the article. Enjoy !

It is a shame that Astronomy Now managed to get the last illustration in the article completely wrong. They credited my image to Ade Ashford, got the camera wrong; it was in fact an MTV-73S85HP-EX-SW-R colour deep-sky Helix Mintron, and the scope is clearly a refractor not a reflector. These things happen :-(

Now you can download the VOB extractor program. It is freeware.

The Sun seems to be finally waking up into Solar Cycle 24
Why not take a look at my eBook on 'Observing and Imaging the Sun with Modest Equipment'

Steve Wainwright

A MTV-73S85HP-EX-SW-R colour deep-sky Helix Mintron and a 10" Newtonian

On a night of very good transparency and no Moon, the MTV-73S85HP-EX-SW-R colour deep-sky Helix Mintron was placed at the prime focus of a 10" Orion Europa Newtonian and trained on M27, the Dumbbell nebula.

Thirty minutes of video was recorded to DVD in High Quality and 282 frame were recovered directly from the DVD as .BMPs.

Deep Sky Stacker was used to register and stack the best 85% (239) images using a 75% scaled dark frame obtained from stacking 176 dark frames. This was the resulting image, rescaled to 640 x 480 before cropping and further post processing was performed in the Gimp

Adjustments were made to levels, colour balance and saturation to produce the final image.

A single frame gives some idea of what the live image on the TV monitor was like


Telescope Planet Mintrons

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The MTV-73S85HP-EX-SW-R colour deep-sky Mintron and an f/4.8 10" Newtonian

An MTV-73S85HP-EX-SW-R colour deep-sky Helix Mintron with a 0.5 focal reducer and an IR cut filter was placed at the Prime focus of a 10" f/4.8 Newtonian.

The video stream was recorded in HQ on DVD. The frames were extracted dircetly from DVD and 281 frames were used (the best 90%) by Deep Sky Stacker to produce the image. A 75% scaled dark frame was used.

This is the image of Caldwell 27 (The Crescent Nebula) obtained.

Caldwell 33, (The Eastern Veil Nebula) was revealed nicely when the best 90% of 176 frames were stacked in Deep-Sky Stacker using a 75% scaled dark-frame.

This image of M82 was derived from the best 95% of 176 frames stacked in Deep Sky Stacker with a 75% scaled dark-frame subtraction.

This image of M13 was derived from 300 frames registered in Deep Sky Stacker and corrected with a scaled dark-frame

The colour balance and levels were adjusted in The Gimp.

Take a look at my eBook on Observing and Imaging the Sun with modest equipment

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An MTV-73S85HP-EX-SW-R colour deep-sky Mintron with a large, fast Newtonian

An MTV-73S85HP-EX-SW-R colour deep-sky Mintron was placed at the prime focus of a 10" f/4.8 Newtonian and the video stream was recorded on DVD.

30 minutes of recording produced a total of 354 unique frames that were extracted from the DVD and stacked with Deep Sky Stacker using a scaled darkframe (derived from stacking 127 frames in Registax).

The scaling could be more accurate, but that is for the future.

This is the resulting image of M57.

The final colour balance and processing was done in The Gimp.

An 0.5 focal reducer lens was placed on the camera and 51 unique frames were recorded to DVD before clouds stopped the session. The frames were stacked in Deep Sky Stacker using a scaled dark frame as above.

This is the resulting image of M27

Some coma was introduced by the reducer, but was not serious. The final colour balance and processing was done in The Gimp.

If you are interested in observing or imaging the Sun, take a look at my eBook on 'Observing and Imaging the Sun with Modest Equipment'.

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An MTV-73S85HP-EX-SW-R colour deep-sky Mintron with a small, fast Newtonian

The MTV-73S85HP-EX-SW-R colour deep-sky Mintron was used at the prime focus of a Skywatcher 130P Synscan AZ GOTO telescope and DVD recordings were made of M13 and of dark-frames. The camera was set at 256 frame accumulation.
M13

176 image frames were extracted from the DVD recording. A dark frame was made in Registax from 127 dark frames extracted from the DVD recording. Deep-Sky Stacker was used to derotate the images, dark-frame correct them, register and stack them. The resulting image was processed in The Gimp to improve the colour balance and levels.

Dont forget to click on 'Older Posts' or 'Newer posts' below or browse the 'blog archive' on the left, or click on 2009 to see all of the posts for this year on one page.

If you are interested in the Sun, take a look at my eBook on observing and imaging the Sun with Modest equipment

Andromeda and Omega with a small fast Newtonian

Imaging with the MTV-22S85HC-EX monochrome 1/2" chip, deep-sky Super Wide field, low amp-glow Mintron

There was a wind blowing at my exposed, south-facing field site. I captured video to DVD and managed to get just 32 frames on 256 frame accumulation. Deep Sky Stacker produced the image below:

This image of M17 (the Swan or Omega Nebula) was taken when the Moon was below the horizon.

The scope used was a Skywatcher 130P Synscan AZ GO TO Newtonian
The dust lanes in M31 showed up nicely in this fast little scope.

Take a look at my eBook on Observing and Imaging the Sun with modest equipment


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MTV-22S85HC-EX monochrome 1/2" chip, deep-sky Super Wide field, low amp-glow Mintron with a 10" f/4.8 Newtonian

The MTV-22S85HC-EX monochrome 1/2" chip, deep-sky Super Wide field, low amp-glow Mintron was fitted with a neodymium filter and placed at the prime (Newtonian) focus of the Telescope. Even with a rising Moon causing sky glow the Crescent Nebula was visible in the real-time image on the TV screen.

These images were extracted from high quality DVD recordings

Cald 27, The Crescent Nebula

Cald 33, Part of the Eastern Veil Nebula

Take a look at my eBook on Observing and Imaging the Sun with Modest Equipment

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The new Mintron 22S85HC-EX 1/2" chip, frame-accumulating Mintron video camera. and more

The Mintron 22S85HC-EX 1/2" chip, frame-accumulating monochrome video camera was featured here two posts ago. It has a 1/2" CCD chip which gives slightly wider fields of view than the 1/3" chip model, the MTV-23S85HC-EX-R. Moreover it has very low amp-glow which is an advantage when the camera is being used as an observation tool.
I am adopting the term 'frame-accumulation' rather than 'frame-integration' as there is some ambiguity in what is meant by 'integration' in this sense.
This post gives a preview of advances in astrovideography that will lead to better quality images and will obviate the need for a computer capture card as long as a DVD recorder is available, or will allow a computer with a capture card to record DVD from which images can be recovered without quality loss.

I have, with Ian Davies, written an article which should appear shortly in 'Astronomy Now' that explains everything. It will also explain how to obtain the freeware software that Ian has developed to acheive this.

In the meantime, here are some results produced with a Celestron C6 and a The Mintron 22S85HC-EX 1/2" chip, frame-accumulating video camera.

The Cat's Eye Nebula, Caldwell 6 using a x2 Barlow


M13 using a 6.3 focal reducer/field flattener



M17, The Swan or Omega nebula (Captured under a full Moon) at the prime focus of a Skywatcher 130P Synscan AZ GOTO Newtonian.

These images were extracted directly from a DVD recording without a capture card and without associated losses in quality.
Watch this space:

Check out my eBook on Observing and Imaging the Sun with Modest equipment, with a foreword by Sir Patrick Moore.

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My PDF eBook on Solar Imaging

My latest news is that I have a PDF ebook available on 'Observing and Imaging the Sun with Modest Equipment'

You can find more information here

Click on the image for more details.

Videography features in this eBook and the H-alpha prominence image on the disk cover was captured with a Mintron video camera through a Coronado H-alpha PST.

The monochrome image has been coloured cosmetically to reflect the monochrome nature of H-alpha light at 656nm in the red.

Mintron Enterprises are making two new modified colour cameras for me that I think will show even greater colour fidelity along with the same H-alpha sensitivity as the MTV-73S85HP-EX-SW-R colour deep-sky Mintron. When these cameras are completed and I have tested them, I shall report on them here if they do represent a significant improvement in performance.

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A Mintron with a 1/2 inch chip and a small AZ Newtonian

Skywatcher 130P Synscan AZ GOTO Newtonian with a Mintron 22S85HC-EX 1/2" chip, frame-integrating video camera.

The equipment was set up as shown and the session was recorded to DVD in High Quality.


Real-time views were very good with very little amp-glow.
The camera was set to 256 frame integration. The image shows M27 in real time.


200 frames were captured from 20min of DVD recording using the GSTAR freeware capture software. A new frame was captured every 5.2 seconds. 25 frames were unchecked in Registax as they were trailed due to wind shaking the scope. The remaining frames were stacked in Registax. The results shows substantial image rotation in the final image.


The individual BMP frames were extracted from the AVI using Virtual Dub and they were imported into Deep Sky Stacker. The same trailed frames were unchecked and the program was told to use the best 80% images for stacking. The resulting de-rotated image is shown below

This small Newtonian AZ GOTO telescope and the Mintron proved to be a useful combination.


Here are two more live views obtained by photographing the TV screen:

M13

and M57

My new PDF eBook

My current news is that I have a PDF eBook on 'Observing and Imaging the Sun with Modest Equipment' The prominence image on the disk cover was captured with a Mintron.

Click on the image for more information.

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Summer with the Colour Deep-Sky Mintron

Colour Deep-Sky Mintron imaging

The MTV-73S85HP-EX-SW-R colour deep-sky Mintron was used at the Prime focus of an f/4.8 10 inch Newtonian to image M57 and M13 and with a 0.5 focal reducer for M51.

The Video was recorded to DVD including dark-frame video and then played back through a capture card and recorded by GStar as an AVI capturing a frame every 5.5s. The dark frame was scaled and used in Registax to correct the registered and stacked frames:

.

The Ring Nebula M57

At the prime (Newtonian) focus

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The Whirlpool galaxy M51

With a 0.5 focal reducer

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M13

At the prime (Newtonian) focus

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Using a Mintron with a scope on an Altazimuth mount

De-rotating a set of Mintron images

A problem with using altazimuth mounts for imaging is that long exposures result in image rotation.

This demonstration was done with a DVD recording of M42 using an 80mm f/5 achromat refractor and an MTV-73S85HP-EX-SW-R colour deep-sky Mintron mounted on a Merlin altazimuth driven mount. Images were captured and combined so that in the resulting stacked image there was no rotation within the image. This was done by experiment and then 4 such stacked images were captured in succession. Although there was no rotation within each stacked image, the images were not derived from many integrated frames. When the 4 images were themselves stacked in Registax, the resulting image showed considerable image rotation.

Image Rotation when simply stacked in Registax

The stars have trailed out into little arcs.

Deep Sky Stacker

However, the freeware software Deep Sky Stacker will de-rotate the images with respect to each other before they are stacked. This was done with the same 4 images and the resulting stacked image showed no rotation, the detail was not motion blurred and the image had a higher signal to noise ratio.

Image produced by Deep Sky Stacker

Deep Sky Stacker does not have the sophisticated wavelet processing posessed by Registax but the de-rotation of images with respect to each other before they are stacked gives more power to an altazimuth mount as an imaging tool in combination with a Mintron or other camera.

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Scaling Mintron darkframes

Capturing an AVI of M101 with GStar
GStar is a freeware AVI capture program written by Steve Massey.

The virtue of this program when capturing AVIs from a frame-integrating camera is that it can be set to capture a frame after a set number of seconds and to concatonate the frames thus captured into an AVI file. As with HandyAVI, this allows the integrated frames to be captured without duplication. Both of these programs work with Windows Vista.

I had captured Video of M101 to DVD with a MTV-23S85HC-EX-R monochrome deep-sky Mintron, at High Quality as in the previous post.
Here I used GStar to capture 200 frames from the DVD recording and store them as an AVI.

GStar capture screen

The characteristic Amp Glow can be seen to the left and top of the image.

I also had captured Dark-frame video to DVD and I used GStar to capture 50 integrated dark-frames to AVI. I stacked the 50 frames in Registax 5 and the result is a dark -frame in which the amp glow is clearly seen as well as vertical banding.

Dark-Frame produced by Registax

If the image AVI is stacked in Registax without using dark-frame correction, the resulting image shows the amp-glow and the vertical banding artifacts

Stacked image data with no dark-frame correction

However, if the dark-frame generated by stacking the dark-frame data is used as the dark-frame in Registax, the correction can be seen to be over compensated and where the amp-glow showed, now that part of the image is too dark. This is because the 256 frame integrating Mintron camera still auto compensates when the scope is covered to produce dark-frame data even if the AGC is set to OFF.

Stacked image using the raw dark-frame

The solution is to scale the dark-frame so that it compensates exactly the correct amount.

This can be done easily if the capturing and registering is being done on the fly in AstroVideo. However, a different approach is needed if other software is used for capture. The scaling must be done by trial and error although it doesn't take long to get the correct degree of scaling.

The dark-frame must be scaled down before it is used in Registax. If it is scaled by the right amount, the resulting image will be properly corrected.

Image resulting from using a dark-frame scaled to 0.56 of its original value.

Scaling a dark-frame using Arithmetic in Paintshop Pro

In this example, the dark-frame is added to itself and then divided by 3. The resulting image is 0.666 of the brightness of the original dark-frame.

The table below shows a simple scheme starting with a dark-frame for generating variously scaled darkframes. This table can easily be extended to produce various levels of scaling:

Table for generating scaled dark-frames using Image Arithmetic

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