x-bit-astro-imaging

Comet McNaught C2009/R1 with a Mintron and an 11" SCT at f/10

2010-06-22T08:05:00.003+01:00

I used an Omega modified 1/2" chip colour Mintron fitted with a light pollution filter to image Comet McNaught. The comet was in the lightest part of the June 21-22 sky, just above and to the west of Capella. I captured 15 min of high quality DVD of the comet and of dark frames. The BMP images were extracted from the DVD with VOB Frame Extractor and the dark-frames were scaled with Dark Frame Scaler. The dark-frame corrected frames were stacked in Registax.

Comet McNaught

Considerable structure is visible in the tail and the movement of the comet against the background stars can be seen by the faint, streaked stars.

Comet McNaught C2009/R1 with a Mintron

2010-06-17T02:39:00.006+01:00

An 80mm f/5 refractor was mounted on a Merlin Altazimuth Autotracking mount with a 1/2" inch chip Mintron fitted with a light pollution filter and an IR/UV cut filter. Comet McNaught was recorded on DVD at high quality for 15min and dark frame data were also recorded.

Comet McNaught C2009/R1

M57 with Mono and Colour Mintrons and an 11" SCT

2010-06-16T13:02:00.006+01:00

I used a half inch chip Monochrome MTV-22S85HC-EX Mintron and a half inch chip OMEGA MTV-72S85H-EX-SW colour Mintron camera at the prime focus of an 11" f/10 SCT. The monochrome image was used as luminance and the colour image was used for chrominance and the two images were combined:

Monochrome Image:

Colour Image:

Combined Image:

The monochrome image captured fine whispy detail at the edges of the nebulae which is visible in the final combined colour image.

Image data and darkframe data were recorded at high quality to DVD. The BMP frames were then recovered from the DVD with no loss of quality using our VOB Frame Extractor software. The darkframes were scaled using our Dark Frame Scaler software. The aspect ratio of the final images was corrected to 4:3

Solar Image with a 1/2" Chip Monochrome Mintron

2010-04-08T18:19:00.003+01:00

A MTV-22S85HC-EX monochrome 1/2" chip Mintron camera was used with a x2 Barlow lens assembly and a H-alpha PST solar scope. Video was captured at shutter speeds to reveal the disk and also to reveal the prominences.
There were numbers of dark filaments as well as some prominences:

The two levels of exposure were combined and the image was colourised to indicate the colour of H-alpha light

Saturn with an Omega 1/2 inch chip colour Mintron video camera

2010-04-01T02:18:00.002+01:00

An unexpected clear spell between the clouds allowed an attempt at imaging Saturn.
An OMEGA 1/2" chip colour Mintron was used with a Skymax 127 with the lens assembly of a Skywatcher x2 Barlow (approx 1.5x) and a Revelation 2.5 Barlow produced this image from 2000 captured frames:

Steve Wainwright

RGB images with a monochrome Mintron and a 6" f/5 achromatic refractor

2010-03-21T22:44:00.003Z

A 6" F/5 Achromatic refractor was mounted on an EQ3-2 polar aligned mount. DVD was captured with red, green and blue filters at each of 256, 64 and 32 frame accumulations. The Mintron 22S85HC-EX 1/2" chip, frame-accumulating video camera also had stacked light pollution and UV/IR cut filters. Opticstar RGB filters and a manual filter wheel were used.

The different images for each colour channel and each level of frame accumulation were stacked in Registax. Then the colour channels were combined using Andrew Sprott's CAP (Colour Alignment Processor) to produce a colour image for each level of frame accumulation which was then processed for levels in the Gimp. Finally the three images for each level of frame accumulation were registered and combined in Andrew Sprott's FIC (Flexible Image Combine) to reveal all parts of the nebula. The Aspect ratio of the image was corrected in the Gimp and the final image was resized down a little.
M42/M43 RGB image

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RGB Colour Imaging with a Monochrome Mintron

2010-03-05T20:52:00.012Z

I had some help with our first experiments on RGB imaging with an MTV-22S85HC-EX monochrome 1/2" chip Mintron. Wayne Jones of the Swansea Astronomical Society used his 130mm F:900mm Newtonian on a driven equatorial mount. He used Red Green and Blue simple colour filters that are not designated for RGB imaging but which have good characteristics of filtering out the other colours.

The technique he used was to place the Mintron back in the focuser in exactly the same orientation after each filter change. This was essential because there was not enough in focus on the scope to use a filter wheel. He has devised an ingenious way of doing this.

AVIs were captured at different levels of frame accumulation for each filter. The unique frames were extracted from the AVIs using VOB Frame extractor which will work on AVI containers as well as DVD VOB files. The frames were stacked in Registax and the different 'exposures' registered and combined in Flexible Image Combine, which computes a weighted average of the frames used. The resulting monochrome images taken through Red Green and Blue filters were registered and combined into an RGB image in CAP (Colour Alignment Processor). The final image was adjusted for levels, colour balance and saturation in The Gimp image processor.

This is the result obtained by Wayne on March 4th; an RGB image of M42:

I used a Skymax 127 on an equatorial mount with a Kson manual filter wheel.

The Red and Green filters were Opticstar Imaging filters and the blue filter was a Kson filter, somewhat darker than the Opticstar one. With hindsite, maybe this was a mistake. 15 minutes of DVD were recorded with each filter and 10 minutes without a filter. However, for all of the video, a Skywatcher light pollution filter was on the nosepiece of the MTV-22S85HC-EX 1/2" chip monochrome Mintron.
The unique frames were extracted from the DVD VOB files and were stacked in Registax.
The resulting monochrome images were registered and combined as RGB colour layers in the CAP software. The final image was adjusted for levels, colour balance and saturation in The Gimp image processing software.

RGB image of the trapezium area of M42

This was the Luminance image

The RGB image produced above was registered and combined with the Luminance image in FIC (Flexible Image combine) weighted averaging software to produce the LRGB image below. The RGB image was given a weight of 6 with the Luminance image having a weight of 1.

LRGB image of the trapezium area of M42

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New 1/2" colour Deep-Sky Mintron for 2010

2010-01-07T00:02:00.014Z

The new 1/2" chip colour Deep-Sky Mintron, the 72S85HP-EX-SW OMEGA has wider fileds of view, better colour fidelity and lower amp glow than the previous incredible 1/3" Helix version. This camera was launched at Astrofest.

M82 with the new 1/2" chip colour 72S85HP-EX-SW OMEGA Mintron with a 10" f/4.8 Newtonian

The Cat's eye Nebula with a 10" f/4.8 Newtonian and a x2 Barlow

The previous post in December 2009 gave the proving results for this camera.

Extracting unique Frames from DVD recordings

The Vob file extractor software as described in my December 2009 article in Astronomy Now can be freely downloaded here.

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 last year on one page.

Advances in colour Mintron deep-sky imaging

2009-12-23T14:34:00.028Z

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.

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.

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

2009-11-19T09:42:00.025Z

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

2009-10-15T12:33:00.010+01:00

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

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.

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

2009-09-27T13:36:00.018+01:00

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

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.

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

2009-09-22T14:42:00.011+01:00

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'.

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.

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

2009-09-20T18:36:00.005+01:00

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

2009-09-15T01:42:00.013+01:00

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

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.

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

2009-09-10T14:55:00.008+01:00

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

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.

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

2009-08-30T00:11:00.019+01:00

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

2009-07-28T23:41:00.012+01:00

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.

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.

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

2009-07-18T16:01:00.016+01:00

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.

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.

Summer with the Colour Deep-Sky Mintron

2009-06-17T00:54:00.010+01:00

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

.
The Whirlpool galaxy M51

With a 0.5 focal reducer

M13

At the prime (Newtonian) focus

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Using a Mintron with a scope on an Altazimuth mount

2009-06-11T21:32:00.013+01:00

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.

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.

Scaling Mintron darkframes

2009-06-10T18:58:00.013+01:00

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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Mintron imaging with a 10" F/4.8 Newtonian

2009-05-31T12:47:00.008+01:00

A Mintron MTV-23S85HC-EX-R monochrome deep-sky frame-integrating camera was used with an Opticstar 0.5 focal reducer and a light-pollution filter at the Newtonian focus of a 10 inch Orion Newtonian reflector. The real-time video was recorded in high quality to DVD. Later the DVD was played back through a capture card and AstroVideo was used with an XP computer to capture 180 frames with a frame captured every 5 seconds with scaled, dark-frame subtraction, registering and summing on the fly. The darkframe was the sum with fixed alignment of 20 frames captured from DVD recorded with the scope covered. The frame was scaled to 0.03 of the summed image rather than the 0.05 as would be expected if the camera did not auto adjust when covered.
M101

I shall experiment with HandyAvi on a Vista computer to capture frames, and dark-frame scaling in other applications before the frames are stacked in Registax.

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.

Capturing images from a Mintron under Windows Vista

2009-05-18T23:20:00.010+01:00

The AVI capture software HandyAvi is ideal for capturing integrated frames from a Mintron under Windows Vista. This is a low cost, high quality piece of software that does not do the on-the-fly integration into 32 bit deep fits files that AstroVideo does, but it does produce AVIs that either it can stack, or Registax can stack.
HandyAvi can be obtained from http://www.azcendant.com/download.htm
It comes with a 170 page manual available in PDF format or readable online at:
http://www.azcendant.com/ViewManual.htm

Screenshot from HandyAvi

Six frames were captured at 5 second intervals: the interval between image updates on maximum, 256 frame integration. HandyAvi can be set to capture at fractions of a second as well so for example, frames could be captured at 2.5 second intervals if required. Play the movie below and note that the second hand of the clock jumps round at 5 second intervals.

I use a KWorld DVD Maker USB 2.0 capture card to capture data from the Mintron to a laptop computer as discussed in an earlier post.

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.

A Mintron, a C6 and focal reduction

2009-04-21T09:13:00.010+01:00

A MTV-23S85HC-EX-R monochrome deep-sky Mintron was used with a C6 Schmidt Cassegrain fitted with a 6.3 Celestron focal reducer and field flattener. The Mintron was also fitted with an Opticstar 0.5 focal reducer on the standard C/CS adapter as well as a Skywatcher light-pollution filter. I could not bring this assembly to focus. However, if I used a half-length adapter, the focal reduction was not so high but The camera could be brought to focus. This was the configuration used to obtain this image of M51. 100 x 256-frame integrated frames were captured, registered and summed in Astrovideo. The resulting FITs file was processed in the Gimp and finished in Neat Image.

The Next two images were obtained using just the 6.3 focal reducer/field flattener.
This image of M57 is the sum of 95 x 256-frame integrated frames.

This image of M13 is the sum of 80 x 256-frame integrated frames

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Focal reduction and image scale with a Mintron

2009-04-19T19:05:00.012+01:00

The standard C/CS 1.25" adapter is about 28mm long. A focal reducer lens will attach to the end of this tube and change the F/ratio of the system, producing an optically faster system with a smaller image scale and wider field of view. I have produced 1.25" adapters of various lengths to demonstrate that different image scales (via different F/ratios) are produced with different length adapters. This is important for some telescopes that are unable to focus in enough when a focal reduced lens is used with a normal length adapter.

Focal Reducer Lens

Mintrons fitted with a 12mm or a 28mm adapter, a focal reducer lens and a light pollution filter.

The MTV-23S85HC-EX-R monochrome deep-sky Mintron was used with an f/10, 6" Schmidt Cassegrain telescope.

M3 with the 0.5 focal reducer and a 28mm adapter

M3 with the 0.5 focal reducer and a 20mm adapter

M3 with the 0.5 focal reducer and a 12mm adapter

The differences in image scale can be seen in these images and can be comparted with the image below produced with no focal reducer.

M3 with no focal reducer

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A Mintron or an eyepiece ?

2009-04-13T09:15:00.011+01:00

If it is visible in the eyepiece, a Mintron camera will produce an image on a TV screen that you will be able to share with others in real time. No waiting in line to peer into the eyepiece. Point at the image on the screen and discuss the structure of the object you are viewing. If you record the video on VCR or DVD you can revisit your observing session on a rainy night. This is an ideal setup for schools, societies, star-parties and public demonstrations as well as individual observing. It is a great way to share the 'eyepiece'.

This is a photograph taken of a CRT TV monitor screen to show what the real time view of M13 was like using a MTV-23S85HC-EX-R monochrome deep-sky Mintron, an Opticstar 0.5 focal reducer lens, a Skywatcher light-pollution filter and a 6 inch Schmidt Cassegrain f/10 telescope. I set up a compact digital camera on a tripod, pointed it at the screen, zoomed in to make the image larger, set a time delay before the shutter fired and pressed the button.

The Video was recorded in HQ onto DVD. 100 x 256-frame integrated frames were captured from DVD, registered and summed on the fly with AstroVideo using dark-frame subtraction to produce this image.

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Versatile Mintrons

2009-04-12T12:07:00.009+01:00

The MTV-23S85HC-EX-R monochrome deep-sky Mintron is good for observing the Sun with a solar telescope such as the PST used here with a 3x Barlow. Registax was used to register and stack frames captured into AVIs for the prominences and disk separately. Andrew Sprott's Solar Layers program was used to combine the final prominence and disk images.

M13 taken with the MTV-23S85HC-EX-R monochrome deep-sky Mintron. A 6 inch f/10 Schmidt Cassegrain was used with an Opticstar 0.5 focal reducer and captured with Astrovideo using scaled dark-frame subtraction.

An MTV-73S85HP-EX-SW-R colour deep-sky Mintron was used with a 3x Barlow. Registax was used to stack and register the frames captured into AVIs.

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The MTV-73S85HP-EX-SW-R colour deep-sky Mintron Video camera for Lunar imaging

2009-04-05T12:12:00.011+01:00

The MTV-73S85HP-EX-SW-R colour deep-sky Mintron is a good lunar and planetary imager for observing or imaging showing the versatility of the camera.

April 4th 2009 an f/10 6" Schmidt Cassegrain was used with the Deep-sky colour Mintron.
The principal settings were: integration was turned of, AGC was on, AWB was used and a
shutter speed selected to give the best exposure.

Clavius and Tycho region at the prime focus.

Crater Clavius with a x2 Barlow.

Crater Copernicus with a x2 Barlow

The region of craters Arzachel, Alphonsus and Ptolomaeus at the prime focus.

The apennine mountains at Prime focus.

Crater Plato at Prime focus

AVIs were processed in Registax.

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MTV-73S85HP-EX-SW-R colour deep-sky Mintron with a Skymax 127 Maksutov

2009-03-27T00:10:00.008Z

With a Skymax 127 Maksutov Cassegrain telescope and a 0.5 focal reducer, this image of The trapezium region of the Orion nebula was obtained. Astrovideo was used to sum 50 integrated frames and dark-frame correction was used.

With a x3 Televue Barlow and the frame integration turned off, Saturn was imaged and captured to DVD. Then 5000 frame AVI was captured from the DVD playback and was used to synthsise the above Image.

With a x3 Barlow and a x1.6 focal extender lens captured a larger image of Saturn, showing the versatility of this camera.

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Colour Deep-Sky MTV-73S85HP-EX-SW-R Mintron with a 10 inch f/4.8 Newtonian

2009-03-22T03:40:00.010Z

M13 the great globular cluster in Hercules (60 x 256 frame-integrated images registered and summed in AstroVideo)

M57 The Ring nebula (50 x 256 frame-integrated images registered and summed in AstroVideo)

M82 using a 0.5 focal reducer and a UV/IR cut filter (50 x 256 frame-integrated images registered and summed in AstroVideo)

M3 using a UV/IR cut filter (60 x 256 frame-integrated images registered and summed in AstroVideo)

M64 The Black-eye galaxy using a 0.5 focal reducer and a UV/IR cut filter (60 x 256 frame-integrated images registered and summed in AstroVideo)

The live images were very good. Data were recorded to DVD and the images extracted from the DVD playback into a capture card.

The globular clusters M3 and M13, the planetary nebula M57 and the galaxy M64 were rather low in the sky so they should improve as the year progresses. There was also local light pollution particularly in the direction of M64.
Dark-frame subtraction with scaling was used in AstroVideo.

Testing the monochrome Mintron 23S85HC-EX-R with a Kson 135mm Newtonian reflector

2009-03-07T17:52:00.006Z

A composite frame from two images synthesised from 50 integrated frames each with dark-frame subtraction
The two images were stitched together using Jon Grove's iMerge software
There was a bright half-Moon above Orion so a Neodymium moon-glow filter was used in conjunction with the 0.5 focal reducer and UV/IR cut filter.

A single frame showing what the live view was like
With a telescope of significant light-grasp, the live views become very good.

Test of Mintron 73S85HP-EX-SW-R deep-sky colour integrating Video camera with a 6" f/5 refractor

2009-03-07T09:07:00.006Z

Integrated image
On March 1 I tested the Mintron 73S85HP-EX-SW-R deep-sky colour frame-integrating video camera using a 6 inch f/5 Helios achromat with a 0.5 focal reducer and a UV/IR cut filter. The live view was incredible and, unlike with an 80mm refractor, was almost as good as the image obtained by summing 100 integrated frames with dark-frame subtraction in Astrovideo.

Single frame showing what the live view looks like

Further tests of the Deep-sky real-time colour Mintron MTV-73S85HP-EX-SW-R

2009-02-22T09:39:00.012Z

The camera was introduced at the European Astrofest on February 6 and 7 in London. There was considerable interest shown.

The sky cleared for long enough to capture 30 minutes of high quality DVD. I also captured 15 minutes of dark-frame data. I used a cheap achromat 80mm refractor and an IR/UV cut filter on the camera which was set to 256 frame integration. The sky didn't stay clear for long enough to capture data at lower exposure to expose the central region of the nebula correctly.

I used the Astrovideo software to capture 100 camera-integrated frames for the darkframe and then 300 camera-integrated frames for the image data with dark-frame correction.

The camera produced good colour rendering of the nebula.

Dark-frame correction got rid of the amp glow that is inevitably inherent with this type of camera.

Some Settings of the camera while the data for the above image were being recorded:

Testing the MTV-73S85HP-EX-SW-R with a 10" f/4.8 Newtonian

2009-01-24T15:22:00.008Z

I tested the modified 256 frame-integrating colour Mintron camera at the prime-focus of a 10" F/4.8 Newtonian telescope. The integration was set to 128 frames and DVD was captured. Just 20 integrated frames were summed in Astrovideo to obtain this image.
Lots of colour was captured as well as lots of detail in the trapezium area. Amp glow is visible at the top left of the image as no dark frames were captured as they would have been if the prime aim was to obtain a still image rather than use the camera as an observation camera.

M1, The Crab nebula proved to be a different matter. The real time video image contained hardly any colour. 70 integrated Mintron frames were captured and summed by Astrovideo and in the final image, some colour had been detected.

This camera can never be as sensitive as the monochrome version due to the presence of the Bayer matrix colour filters in front of the pixels effectively excluding some of the light.

For comparison, below is a monochrome image of M1 taken with the Mintron MTV-23S85H-EX-R monochrome camera taken on the same night with the same scope. With both cameras the frame integration was set to 256 frames and an 0.5 focal reducer was used in conjunction with an IR/UV cut filtere

An experimental Mintron MTV-62V8H-EX colour camera modification

2009-01-17T21:15:00.011Z

On December 30th 2008 I modified an MTV-62V8H-EX 128 frame-integrating colour camera. I then asked Mintron to make to the MTV-73S85HP-EX-SW-R colour deep-sky Mintron to a similar but improved modification at manufacture time, to produce a 256 frame integrating deep-sky colour camera.

The modified MTV-62V8H-EX colour camera was attached to a Skywatcher Equinox 80mm fluorite apochromatic refractor and focussed on the Orion nebula. The video stream was recorded to DVD at high quality with the camera set to 128 frame integration.

150 integrated frames were registered and stacked by Astrovideo to obtain the image here.

The next tests I do with this modified camera will be to make a side by side comparison with the unmodified camera.
This is a single integrated frame captured from the real time video stream and shows what is seen on the TV screen.

Why do Astrovideography ?

2009-01-16T15:45:00.012Z

Astrovideography is an exciting and less demanding form of astronomical imaging than other methods. I prefer to call this form of imaging 'Observational Imaging'. This is a very pleasing form of 'sharing the eyepiece' as a number of observers can see what is being viewed at the same time on the TV screen. Using video signal splitters, the live video stream can be enjoyed indoors on a TV screen while a smaller version of the screen can be outside by the telescope. The video can be recorded to DVD or video-tape for viewing again later. If your telescope mount is not well polar aligned, or is an altazimuth driven mount, image rotation or image drift will be far less important if your primary aim is to capture and view your astronomical images on the TV screen.

That notwithstanding, it is still possible to capture video frames and to combine them into quite pleasing still images even with quite modest equipment. This image of M27 was obtained with a Celestron Astromaster 130 Newtonian and a Mintron 23S85HC-EX-R monochrome, frame-integrating video camera.

I shall be testing the various Mintron cameras with a variety of telescopes of all sizes over the next few months and showing some of the results on this blog.

The new deep-sky colour Mintrons that we are developing will be launched at the European Astrofest by Telescope Planet

Watch this space!

Developing a real-time deep-sky colour frame-integrating Mintron video camera

2009-01-15T15:58:00.019Z

Since I have been working in the Telescope Planet showroom http://www.telescopeplanet.co.uk/ I have had the opportunity to test various pieces of astronomical equipment. The 256 frame integrating Mintron video cameras were an exciting opportunity. There is a monochrome version the MTV-23S85H-EX-R and also a colour version: the 73S85HP-EX. This is a fine colour camera for colour, low-light surveillance applications but not so good as a deep sky colour, real-time imager.

I asked Mintron to make a modification to the camera which has made it much more sensitive and suitable as a real-time colour, deep-sky imager. This has been given the designation MTV-73S85HP-EX-SW-R for me.

The MTV-73S85HP-EX-SW-R Mintron real-time deep sky frame-integrating video camera

First light was a test DVD recording and two directly captured images using an f/5 achromatic 80mm Orion refractor.

M42 & M43

Here is a snapshot of the TV screen showing what the live display is like. The nebula was a very pleasing live image. When 115 frames were integrated as shown above, the resulting image was quite good.

The telescope was mounted quickly on a Merlin AZ autotracking mount and an IR/UV cut filter was used. the Mintron was set to 256-frame integration. 30 minutes of DVD was recorded and Astrovideo was used to capture a frame every 5s for 55s and another image was captured at the same rate of capture for 60s. The frames were summed on the fly and were saved. The images were de-rotated and merged using Picture Window software. It would have been far better to have used an equatorial mount but I had very little time from my location to capture the data as I had been out earlier giving a talk to the Port Talbot Astronomical Society. The Merlin mount can be up and running in 3 minutes.

Since then, the Moon has been a more serious problem and the weather has been poor. The next tests will be done with an equatorial mount so that far more frames can be integrated to produce a final image. I shall use an Apochromatic 80mm refractor next time to image the Orion Nebula and a 10 inch f/4.8 Orion Europa Newtonian to attempt the Crab nebula. This will be done on the first clear sky without the Moon.

Capturing Video to DVD or directly to computer

2009-01-14T00:02:00.018Z

Video can be recorded on a DVD or video-tape and can be watched again in the future. The recording settings should always be set to the highest quality.DVD recordings give the highest quality, next is Super VHS which is almost as good as DVD. The poorest quality recordings are made on VHS video-tape. I prefer to record to DVD at the highest quality setting and then capture from the DVD playback video stream.

If a digital camera is placed on a tripod and set up in front of the TV screen displaying the live image it can be used to capture a screenshot that will be a reasonable image. If the ISO value is set low and the timer shutter release is used so that no shake is introduced into the camera, the shot will integrate several frames and avoid the raster scan if a cathode ray tube monitor is used.

Digital photograph of the screen of a CRT monitor displaying a video image of the Moon

Video can also be captured directly to a computer via a capture card such as the EasyCap USB 2.0 capture device.

This device connects to the computer via a USB 2.0 port and accepts composite or SVideo inputs.

PAL to VGA aspect-ratio correctionA problem I found with this device is that it does not allow for capture of PAL TV at 640 x 480 resolution. PAL resolution is the default capture size and this has a resolution of 720 x 576. The problem is that at this resolution, the aspect ratio of the image is distorted from 640 x 480 to the 720 x 576 PAL resolution. Thus circles appear as ellipses with the long axis being in the vertical dimension. Now, 640 is 0.8888 of 720 and 480 is 0.8333 of 576. To correct the aspect ratio of any image captured at the PAL resolution, even if the image has been cropped, you simply resize the image (making sure that the aspect ratio is not preserved) so that the horizontal dimention is changed to 0.8888 of the original dimension and the vertical dimention is changed to 0.8333 of the original dimension. This can be done in most image manipulation programs such as the Gimp, Paintshop Pro and Photoshop. Some capture cards allow capture to be made at 640 x 480 with no distortion of the aspect ratio of the objects in the image. This just has to be regarded as part of the image extraction process.

There is a better capture device that does allow capture of 640 x 480 from PAL TV and thus avoids the aspect ratio distortion problem. This is the KWORLD DVD Maker USB 2.0

With one of these capture devices and the appropriate capture software your Mintron becomes a USB camera.

When long integrations of for example, 256 frames are used, the image is updated about every 5s or for 128 frame integrations the video image is updated about every 2.5 seconds.

I use the AstroVideo video capture software http://www.coaa.co.uk/astrovideo.htm which can be set to capture a frame every 5s (5000ms) for example and to align and sum them on the fly. The captured frames can be saved as an AVI that can be processed in Registax, or the summed frames as a FITs file either 16 bit or 32 bit deep or a BMP.

Mintron MTV-23S85H-EX-R

2009-01-11T12:37:00.002Z

Recently, another camera suitable for real-time deep sky imaging has been produced by Mintron. This is the Mintron MTV-23S85H-EX-R monochrome video camera which has a 0.33 inch CCD sensor and up to 256 frame integration

Mintron Mintron MTV-23S85H-EX-R monochrome video camera (0.33 inch CCD sensor) 256 frame integration

Image of M1 the Crab Nebula captured from the video stream from the Mintron MTV-23S85H-EX-R camera with a 0.5 focal reducer and an F/4.8 10 inch Newtonian.

Image of the limb of the Sun in H-alpha light using a x3 Barlow and a Coronado PST H-alpha solar telescope. Image captured on Dec 6th 2008
These cameras can be used to capture bright or faint objects as these images show.

x-bit-astro-imaging

2009-01-08T13:14:00.011Z

X-bit-Astronomical imaging refers to the fact that I use cameras with different bit depths of output for astronomical imaging.

In general, purpose-built astronomical cameras have 16 bit ADCs and produce output with 65536 levels of brightness.

This means that non-linear image processing can be used to brighten up the very faint parts of an image without oversaturating the brighter parts. The 16-bit depth allows this to be done with high precision.

There are many cameras that have been produced for other purposes such as webcams and surveillance cameras that typically have 8-bit output with 256 levels of brightness. This fine for display purposes as computer type monitors have 8-bit displays. The problem is that with only 256 levels of brightness, different real levels of brightness are contained within a particular band of the 8-bit data. Most of the cameras I use are 8 bit devices.

I will begin here with the 8-bit Mintron Frame-integrating surveillance cameras that can be set to synthesise long exposures by integrating up to 256 video frames in some models and which output a continuous video stream that is updated at a rate determined by the level of frame integration selected. For example, with the integration set to 256 then the image in the video stream is updated about every 5 seconds.

MTV-12V5HC-EX monochrome video camera (0.5 inch CCDsensor) 128 frame integration

Images taken with the MTV-12V5HC-EX and an f/4.8 10" Newtonian

M13

M57

M27

M82

I was one of the first astronomers to use Mintron cameras about 10 years ago when I introduced them to my imaging group QCUIAG (an acronym for QuickCam and Unconventional Imaging Astronomy Group) http://www.qcuiag.co.uk/

Bev Ewen Smith at COAA in Portugal, with my help, developed some capture software called AstroVideo (works under Vista in XP SP2 compatability mode), that enables the integrated frames to be captured and saved in an AVI or to be saved as individual 32-bit deep FITs files as well as being registered and summed on the fly into a 32-bit FITs file. The program was my idea, Bev did all of the coding and I did extensive testing of the software. This program now has a large user base. I use AstroVideo for capturing data from Mintron frame-integrating cameras.