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Messages - Dimitris Platis

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General / Re: Star Size Reduction - When?
« on: 2015 December 13 03:02:36 »
The reason u wont find it in the manual is because there is no correct 'when'. It depends on your image.
Usually its a good idea to implement it right after stretching...because usually its better to go forward rather than fix everything and then go backwards.
A medium stretching followed by star reduction and then some more stretching I have found is ideal

General / Re: STF
« on: 2015 December 11 10:16:57 »
Do u recognize the nuclear symbol?

General / Re: STF
« on: 2015 December 10 23:15:43 »
That STF icon is from an ancient version of Pix.
It is definitely not from 1.8.

General / Image calibration - Pedestal
« on: 2015 December 09 09:49:21 »
I am using a QHY9M for imaging. People who r familiar with this camera can see that in the driver control panel (where u can set gain and offset) there is a section named 'Overscan Processing' where the pedestal is mentioned.
Mine is set at default 500.
Should I set this value at the appropriate section in Image Calibration or is it irrelevant because it is common to all calibration frames (bias, darks, flats)?

General / Re: Deconvolution question
« on: 2015 December 02 04:38:01 »
Deconvolution is not a way of making circular stars. It is used for bringing up details, sharpening, enhancing. A side effect is making stars sharper.
The luminance chance is responsible for these effects, u dont need to apply on RGB. In fact, many times its better if RGB is more blurry so u can avoid pronounced  noise

Gallery / Drowned in Dust.. (M81/M82/Volcano Nebula)
« on: 2015 November 28 06:19:17 »
What a pleasure to be able to shoot 2 targets in one weekend, mainly because of being able to use my lens at f2.8...and ofcourse because of the excellent weather in Greece. Unfortunately, this lens produces horribly bloated blue I had to come up with an entirely new way of dealing with this problem.......I think I managed to contain the issue.....Hope u like it.

 The ?81/?82 galaxy pair in the constellation of Ursa Major are a rather popular object for astrophotographers. Located at a distance of 12 million light years, being 150,000 light years from each other.
Our Galaxy is surrounded by molecular clouds of dust, hydrogen, carbon monoxide and other elements expelled by our Galaxy. In contrast to nebuli, where molecular clouds are illuminated by the light of the stars, the nebulosity in this region is illuminated by the light of the Galaxy itself, therefore earning the name Integrated Flux Nebulae. These molecular clouds are of extremely low surface brightness and it requires significant effort to bring forth.
The region besides the M81/M82 galaxy pair, it contains an IFN region known as Volcano Nebula (MW3) as well as many other galaxies of lower brightness. M81, also known as Bode’s Galaxy, because it was discovered by Bode in 1774 has a diameter of 92,000 light years, while M82, also known as Cigar Galaxy, has a diameter of 37,000 light years and is at an extremely active phase of star formation. 
Immediately, at the left of M81, barely visible, we can see the companion galaxy of M81, Holmberg IX, while a bit more to the left we can observe the Seyfert galaxy NGC3077. At the middle and down of the image we can see galaxy NGC2976, while to the right the rather less bright NGC 2892 is located. Finally, at the middle right of the image NGC2787 is visible.
At the right upper quadrant of the image the Volcano Nebulae is clearly visible along with the brightest star of the area, 24 Ursa Majoris.

Higher resolution (


Location: Mount Parnonas, Greece (1400m)
Constellation : Ursa Major
Imaging scope: Nikon 180ED (@f2.8)
Imaging CCD: QHY9M (-20°C)
Guiding CCD: Lodestar
Mount: Skywatcher EQ6
Guiding scope: APM optical finder 240mm FL
Image scale : 6.28 arcsec/pixel
Filters: 2''Baader
Luminance bin 1X1 152x2min
RGB bin 1x1 20x2minsec
Calibration frames :
Darks 25x, Flats 25x, Bias 100x, Dark Flats 25x
Calibration/Processing : Pixinsight 1.8
Capture : Sequence Generator Pro
Tracking : PhD2 2.5.0

Gallery / Re: Melotte 15 Narrowband
« on: 2015 November 21 10:00:49 »
Indeed... :surprised:

Just tried works....sometimes though it is confused by stars that are immediately adjacent....especially in large stars....however, very very useful method....well done

How do u focus the mask only on stars? Why dont u get color reduction in the background also?

Gallery / The Heart and Soul of the Night Sky....
« on: 2015 November 18 13:12:26 »
The Heart and Soul Nebula are among the most beautiful in the night sky. 7500 light years away, hot radiant gases among dark molecular clouds of ionized gas and hydrogen produce a spectacular sight.

I had some problems with my lens, which I managed to fix (just a matter of mounting it right) and I decided to go full speed with the lens. So I opened it up to f2.8 and tried high bin for OIII/SII.....
Hope u like it....

U can find a link to higher resolution here (

Location: Parnon, Greece (1400m)
Constellation : Cassiopeia
Imaging scope : Nikon 180ED
CCD : QHY9M (-20°C)
Guiding CCD: Lodestar
Mount : Skywatcher EQ6
Guiding scope : APM optical finder 240mm FL
Image scale : 6.28 arcsec/pixel
Filters : 2''Baader

Subexposures :
Ha bin 1X1 5X1200sec
OIII/SII bin 3X3 20X300sec

Calibration frames :
Darks 25x, Flats 25x, Bias 100x, Dark Flats 25x
Calibration/Processing : Pixinsight 1.8
Capture : Sequence Generator Pro
Tracking : PhD2 2.5.0

There is a script in Pixel math that removes magenta halos from stars.....

I would love it if u could add this technique for star cores (as well as the star reduction with multiple masks from the other post) in your newest edition cribsheet so we can have everything together and not waste time looking around.


To tell u the truth I have been thinking myself to take shorter exposures just for star color because normal RGB exposures tend to produce white star cores......
Perhaps u could experiment with differential stretching for stars and then copy the stars to ur RGB image

Well dont forget that normal monitor probably are incapable to exhibiting the huge dynamic range required for what u r asking.
A difference of 0.1 or smaller among the color in the core of the star is difficult to show.

Perhaps u should try my method and then do HDR followed with color saturation

That looks great.
Havent looked into TGVInPaint...but I will now.

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