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Re: [ccd-newastro] M37 imaged December 26, 2005 What could make it better

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  • Doug McE
    G day Charles, What my inexperienced eye is seeing: Deformed stellar images that might be improved (rounded out) by the acquisition of more sub frames. Colour
    Message 1 of 35 , Dec 3, 2005
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      G'day Charles,
      What my inexperienced eye is seeing:
      Deformed stellar images that might be improved (rounded out) by the acquisition of more sub frames.
      Colour fringing that is not concentric with the main stellar image.
      I am aware of two basic colour conversion methods for one shot colour ccds, AIP4Win has about 4 offset options and gives you 3 colour panes to recombine to RGB.
      MaxDSLR (Maxdl I suppose as well) gives you four offset options as well but delivers an RGB in one op.
      CCDsoft I don't know but I guess it would use one or the other systems.
      My point is that if you are being given 3 panes to combine to RGB after colour conversion, there might be a slight registration issue there.
      I truely wish I could give you the correct/specific URL but I can point you in this general direction: browsing around in the PixInsight web pages I did come accross a tutorial on precessing stellar colour, and their example images were nothing short of spectacular.
      If you are of a mind, you might like to snoop around there and see if you can find anything of value.

      http://www.pleiades-astrophoto.com/pixinsight/

      best,
      Doug
      ----- Original Message -----
      From: Charles Bell
      To: ccd-newastro@yahoogroups.com
      Sent: Thursday, January 05, 2006 9:48 AM
      Subject: [ccd-newastro] M37 imaged December 26, 2005 What could make it better


      M37 imaged December 26, 2005

      http://www.quantumhyperspace.com/imagefiles/M37-12262005.jpg

      12 x 60 second exposures
      Imaged with 12 inch Meade 200LX + ST-2000XCM + AO7

      minimal processing applied.

      What do you think should be done to make it better?

      Any longer exposure and the orange stars will be
      washed.
      I think many of the blue stars are washed white.

      Thanks







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    • Wodaski Yahoo
      Our layout person is out on medical leave until later this month. Her fiancé was very ill - was in intensive care for most of December. We have most of the
      Message 35 of 35 , Jan 11, 2006
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        Our layout person is out on medical leave until later this month. Her fiancé
        was very ill - was in intensive care for most of December.

        We have most of the chapters ready to go, but when she gets back, we'll wrap
        up the layout and editing on the few remaining chapters and send the book
        off to the printer.


        Ron Wodaski
        http://www.newastro.com


        -----Original Message-----
        From: ccd-newastro@yahoogroups.com [mailto:ccd-newastro@yahoogroups.com] On
        Behalf Of Chris Curran
        Sent: Wednesday, January 11, 2006 6:30 AM
        To: ccd-newastro@yahoogroups.com
        Subject: [ccd-newastro] Zone book

        Ron,

        You must have missed this in the noise... What's the status of the
        Zone book?

        Chris

        --- In ccd-newastro@yahoogroups.com, "Chris Curran"
        <curran.chris@g...> wrote:
        >
        > Ron,
        >
        > You need to update your page - it states that it is scheduled for Dec
        > 2005 release - obviously that didn't happen. Any new news on a new
        > release date?
        >
        > Chris
        >
        > --- In ccd-newastro@yahoogroups.com, "Wodaski Yahoo" <yahoo@w...> wrote:
        > >
        > > Sorry for the late reply - I had a major server crash and this email
        > message
        > > got lost in the shuffle.
        > >
        > > Anyone interested in the new book can get information here:
        > >
        > > http:/www.newastro.com/ipb
        > >
        > >
        > > Ron Wodaski
        > > http://www.newastro.com
        > >
        > >
        > > -----Original Message-----
        > > From: ccd-newastro@yahoogroups.com
        > [mailto:ccd-newastro@yahoogroups.com] On
        > > Behalf Of Dale
        > > Sent: Saturday, December 31, 2005 11:14 PM
        > > To: ccd-newastro@yahoogroups.com
        > > Subject: [ccd-newastro] Re: A colorful cluster of stars
        > >
        > > What is the title and where can I purchase your book that covers
        > > Zone processing. I own your privious book and it has been
        > > instumental in my learning process. I would Love to get your newest
        > > book.
        > >
        > > --- In ccd-newastro@yahoogroups.com, "Wodaski Yahoo"
        > > <yahoo@w...> wrote:
        > > >
        > > > "Modify, Expand and Feather" is shorthand for a series of
        > > techniques that
        > > > are part of the zone system. The idea is to use Select | Modify |
        > > Expand to
        > > > enlarge the selection of the stars (the making of which is a whole
        > > other
        > > > topic) so that you pick up a little background around the stars.
        > > The amount
        > > > will vary with your image scale, quality of optics, the seeing on
        > > a given
        > > > night, etc. Feathering is usually 25 to 75% of the expansion, and
        > > again the
        > > > amount varies with the circumstances of the image and conditions.
        > > >
        > > > This is covered in detail in the new book on the Zone System;
        > > there is an
        > > > entire chapter just on star selection. It gets more complicated
        > > than one
        > > > would imagine; there is no simple answer of so many pixels - one
        > > has to
        > > > learn to make judgments based on your data and your equipment.
        > > >
        > > >
        > > > Ron Wodaski
        > > > http://www.newastro.com
        > > >
        > > >
        > > > -----Original Message-----
        > > > From: ccd-newastro@yahoogroups.com [mailto:ccd-
        > > newastro@yahoogroups.com] On
        > > > Behalf Of nraider217@c...
        > > > Sent: Saturday, December 31, 2005 2:09 AM
        > > > To: ccd-newastro@yahoogroups.com
        > > > Subject: Re: [ccd-newastro] A colorful cluster of stars
        > > >
        > > > Thanks for the info on this image, as preserving star colors has
        > > been
        > > > difficult for me at times. In the image processing where you spoke
        > > of the
        > > > manner in which you sharpened your star images , you stated to
        > > remember to
        > > > "Modify, Expand and Feather' before you apply the unsharp
        > > masking. Could
        > > > you please share, how much to expand the selection ( 1
        > > pixel ?) , and the
        > > > proper way to feather prior to applying the sharpening filter.
        > > Thanks
        > > > again.
        > > >
        > > Dale
        > > >
        > > > -------------- Original message --------------
        > > > From: "Ron Wodaski" <yahoo@w...>
        > > > I don't get many opportunities to image these days, but I was
        > > testing
        > > > hardware last night and took enough images to actually make
        > > something nice.
        > > > <G>
        > > >
        > > > This is an image of the open cluster NGC 1245, taken with the 20"
        > > RC. The
        > > > seeing was pretty soft, so I made the most of it by imaging binned
        > > 2x2 and
        > > > using short exposure time to avoid saturating most of the stars
        > > (this helps
        > > > preserve star color). I increased saturation somewhat to make the
        > > star
        > > > colors more obvious:
        > > >
        > > > http://www.bb-obs.com/img/rc20/11000/NGC_1245_RGB_2b.jpg
        > > >
        > > > Here are some tips for getting good star color in cluster images:
        > > >
        > > > * Poor seeing can actually be your friend, and you can get the same
        > > > advantages by going slightly out of focus. The idea is to spread
        > > the
        > > > starlight out a bit, and avoid a saturated core for most of the
        > > stars. You
        > > > can use some careful unsharp masking to tighten the stars up if
        > > the soft
        > > > look doesn't work for you. This image is a 50-50 mix of a soft
        > > image and a
        > > > sharpened image.
        > > >
        > > > * Keep your exposure times fairly short. Even if you are using an
        > > ABG
        > > > camera, star cores will saturate quite easily. You'll need to
        > > strike a
        > > > balance between exposures short enough to avoid saturation on most
        > > stars,
        > > > but long enough to capture the dimmer stars.
        > > >
        > > > * When processing, use a very compressed Curve in Photoshop. The
        > > curve
        > > > should be sharp at the left (dark) end, and flat for 75% or more
        > > of the rest
        > > > of the curve. The idea is to boost dim areas while NOT compressing
        > > the
        > > > bright areas very much. If you compress the bright stuff (with a
        > > curve that
        > > > isn't mostly flat) too much, the star cores will saturate (clip,
        > > or close to
        > > > it) and you will lose that color you wanted.
        > > >
        > > > * You might want to try sharpening in two steps: select just the
        > > brightest
        > > > stars with Color Range (maybe half to two thirds of all the
        > > stars), and
        > > > apply a moderate sharpening (1.0 - 1.7, 50% amount, zero
        > > threshold), and
        > > > then select as many stars as you can and apply a light sharpening
        > > (0.6 to
        > > > 1.0). Remember to modify/expand and then feather before you apply
        > > the
        > > > filter.
        > > >
        > > > * The background will likely need smoothing because of high read
        > > noise due
        > > > to short exposure times.
        > > >
        > > >
        > > > Ron Wodaski
        > > > http://www.newastro.com <http://www.newastro.com/>
        > > >
        > > >
        > > >
        > > >
        > > >
        > > >
        > > > [Non-text portions of this message have been removed]
        > > >
        > > >
        > > >
        > > >
        > > >
        > > >
        > > >
        > > >
        > > >
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        > > > Yahoo! Groups Links
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