O/H Richard Crisp έγραψε:
>
> I'm eager to see it

Well, I was *** floored *** at the quality of the non-reduced master h-alpha and
O-III results and I suspect there is a reaaly sweet gem waiting to surface.

What really pissed me off was the damn flats .... I had to go to 5 minutes per
sub and to do so at 4:30 in the morning (ie. dead tired after the all-nighter).
For my LRGB flats, we are talking seconds ... for narrowband, we are talking
minutes! I will also get flat-darks this evening just to be complete.

>
> I think the reason most try to synthesize green dates back to film days.
>
> with Tech Pan and color filters, shooting red and blue and then making
> an artifical green sort of makes sense since the green is so full of sky
> light pollution
>
> but that's broadband and broadband behaves differently than narrowband
> relative to light pollution.
>
> the key things to consider for nebulae are the strongest emission lines
> and those are typically Hydrogen Alpha and Beta and [OIII] and their
> wavelengths versus color channel wavelength boundaries.

This is good to know and which explains why almost everyone turns their back on
S-II integrations. If time were more of a luxury, I would love to do some
testing for my own curiosity and interest.

>
> There's [SII] but it is typically weak. There's also [NII] but it is so
> close to Ha that it is hard to separate typically.

Okay, thanks.

>
> The key thing that affects the hue of the red is maintaining the balance
> between Halpha and Hbeta. The Hbeta emission occurs in a statisical
> ratio to the Halpha set by quantum mechanics. The source ratio is in the
> range of 2.92 to 1 in favor of the alpha transition.

I read on your website the other day.

>
> So if you observe those facts and consider where these emission lines
> reside in the visibile spectrum, the solution should be obvious
>
> Unfortunatly old habits die slowly and for most that mindlessly copy
> what others do without even giving a thought to the physics behind it,
> you will continue to see people making a synthetic green channel because
> they simply don't get it or are too stubborn to admit they are wrong....
>
> I find it a waste of time to try to educate those types: they don't have
> the background to understand the science behind this stuff typically and
> seem to be perfectly happy wallowing in ignorance and simply copying
> what the other guy does and thinking it looks good but still unclear why
> it doesn't look like it should...

Sometimes it is best for someone to get going with something and to slowly pick
up the reasons and rationale for the various intermediate steps involved as they
evolve personally. It is similar to owning and driving a car ... get the damn
license first and become a good driver and then worry about the mechanics of
internal combustion, aerodynamics etc. as the needs and interest arise (if and
when they do).

Anthony.

>
> -----Original Message-----
> >From: Anthony Ayiomamitis <ayiomami@...
> <mailto:ayiomami%40otenet.gr>>
> >Sent: Jul 9, 2009 8:25 AM
> >To: ap-ug@yahoogroups.com <mailto:ap-ug%40yahoogroups.com>
> >Subject: Re: [ap-ug] Re: M17: amateur and ESO
> >
> >Richard,
> >
> >That was my suspicion and planned methodology.
> >
> >Back later this evening with the processed NGC 6992 in both HST and
> CFHT palettes as well as exoplanet WASP-2b in transit.
> >
> >Thanks.
> >
> >Anthony.
> >
> >O/H Richard Crisp έγραψε:
> >>
> >> Anthony
> >>
> >> I use pixel math to perform the synthesis of the Hbeta to create the
> >> blue channel
> >>
> >> I sum them as this: Blue = O3 + 0.3* Halpha
> >>
> >> then I use stretch to stretch to 16 bits (max value stretch)
> >>
> >> then in photoshop I do the color combine and adjust levels to get
> >> everything lined up correctly
> >>
> >> ----- Original Message -----
> >> From: ayiomamitis
> >> To: ap-ug@yahoogroups.com <mailto:ap-ug%40yahoogroups.com>
> <mailto:ap-ug%40yahoogroups.com>
> >> Sent: Thursday, July 09, 2009 8:16 AM
> >> Subject: [ap-ug] Re: M17: amateur and ESO
> >>
> >> Richard,
> >>
> >> I will be sitting down this evening to get my dark frames for last
> >> night's (test) imaging session under the full moon and involving the
> >> eastern Veil (NGC 6922) taken with Baader narrowband filters (h-alpha @
> >> 10x15', O-III @ 10x15'') and my AP160 with AP 0.75x 27TVPH reducer.
> >>
> >> I would like to add the correction for h-beta using the scaling you
> >> describe below and I would like to confirm how best to do so. For
> example,
> >>
> >> (1) using pixel math, do we create a new image which is the sum of
> O-III
> >> and 0.3 h-alpha and then remap all pixel values >65535 to 65535 ....
> or ....
> >>
> >> (2) in PS, do we layer the h-alpha, change opacity to 30% and use
> >> "lighten" for blending mode .... or ....
> >>
> >> (3) ????????
> >>
> >> At the same time, I would like to produce a synthetic green (S-II)
> using
> >> the mean of the h-alpha and O-III (Rolando does this frequently). Is
> the
> >> O-III to be used the original O-III or the corrected O-III and which
> >> includes the h-beta correction? Logic would dictate the latter.
> >>
> >> Out of curiosity, I will have a result using both the HST and CFHT
> >> palettes. In looking at the non-reduced master h-alpha and O-III
> >> results, the result is quite impressive and in spite of the heavy
> >> (lunar) light pollution during the complete evening.
> >>
> >> Anthony.
> >>
> >> --- In ap-ug@yahoogroups.com <mailto:ap-ug%40yahoogroups.com>
> <mailto:ap-ug%40yahoogroups.com>, Richard
> >> Crisp <rdcrisp@...> wrote:
> >> >
> >> > looks good to me
> >> >
> >> > you may want to consider how to place the emission lines such that
> >> you approximate their location in nature
> >> >
> >> > the Halpha is in the red while O3 is in both green and blue
> >> >
> >> > the other major emission line in blue is hbeta and that looks
> >> identical to halpha but weaker by a factor of 2.92:1
> >> >
> >> > so a reasonable approximation of the placement of the major emission
> >> lines is:
> >> >
> >> > Synthetic RGB prescription:
> >> > red = halpha
> >> > green = o3
> >> > blue = o3 + hbeta =~ o3 + 0.3*Halpha
> >> >
> >> > spectrogram showing the major emission lines:
> >> > http://www.narrowbandimaging.com/images/brazell_emission.jpg
> <http://www.narrowbandimaging.com/images/brazell_emission.jpg>
> >> <http://www.narrowbandimaging.com/images/brazell_emission.jpg
> <http://www.narrowbandimaging.com/images/brazell_emission.jpg>>
> >> >
> >> > explanation of why to assign the lines as outlined in the above
> >> prescription...
> >> > http://www.narrowbandimaging.com/synthetic_rgb_page.htm
> <http://www.narrowbandimaging.com/synthetic_rgb_page.htm>
> >> <http://www.narrowbandimaging.com/synthetic_rgb_page.htm
> <http://www.narrowbandimaging.com/synthetic_rgb_page.htm>>
> >> >
> >> >
> >> >
> >> > -----Original Message-----
> >> > From: chris1011@...
> >> > Sent: Jul 7, 2009 8:04 AM
> >> > To: ap-ug@yahoogroups.com <mailto:ap-ug%40yahoogroups.com>
> <mailto:ap-ug%40yahoogroups.com>
> >> > Subject: Re: [ap-ug] Re: M17: amateur and ESO
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> > In a message dated 7/7/2009 9:59:12 AM Central Daylight Time,
> >> > rdcrisp@... writes:
> >> >
> >> > > it is interesting to me how few people shoot M17 in tricolor
> emission
> >> > > line and shoot M16 instead.
> >> > >
> >> >
> >> > http://geogdata.csun.edu/~voltaire/roland/m17b.html
> <http://geogdata.csun.edu/~voltaire/roland/m17b.html>
> >> <http://geogdata.csun.edu/~voltaire/roland/m17b.html
> <http://geogdata.csun.edu/~voltaire/roland/m17b.html>>
> >> >
> >> > Not tricolor, but duo color narrow band.
> >> >
> >> > Rolando
> >> >
> >> > **************
> >> > An Excellent Credit Score is 750. See Yours in Just 2
> >> > Easy Steps!
> >> >
> >
> >
> >------------------------------------
> >
> >
> >To UNSUBSCRIBE, or for general information on the ap-ug list
> >see http://groups.yahoo.com/group/ap-ugYahoo
> <http://groups.yahoo.com/group/ap-ugYahoo>! Groups Links
> >
> >
> >
>