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September Competition Theme - Star Clusters (2006)

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Replied by ayiomamitis on topic Re: September Competition Theme - Star Clusters

Okay, Dave, I will supply the AP160 (and Greek weather) and you supply the AP1200GTO. :wink: :lol:


Done!

Seanie - whatever Anthony submits for this months competition is a joint submission :D

Woo hoo - how can we lose eh Anthony? :lol:

Dave,

Indeed how can we lose?! I made some slight modifications to the processing of our test photo at www.perseus.gr/Astro-DSO-NGC-6913.htm which I hope you approve. If so, we can use the new and improved processing for our official entry shortly involving NGC 457 in Cas.
Anthony Ayiomamitis
Athens, Greece
www.perseus.gr
15 years 2 months ago #33166

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A couple of questions Anthony:
1. Why no flat?
2. Why 1:1:1 RGB ratio?
3. Where do the diffraction spikes come from?

Dave
15 years 2 months ago #33167

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Replied by ayiomamitis on topic Re: September Competition Theme - Star Clusters

A couple of questions Anthony:
1. Why no flat?

Unfortunately I am not an electronics guru ... in fact more like an ignoramus! I asked a friend who is quite active with electronics to construct me a light-box but he has dragged his feet quite a bit. I have asked another friend to get me the electronics only done but he is busy with a baby coming due shortly.

Yes, we have t-shirt and sky flats but I am not sold on them. The problem with flats is that they can do more damage than good if not taken properly.

2. Why 1:1:1 RGB ratio?

That is only for the exposures themselves. I weigh each of the master RGB files prior to constructing my master RGB using calibration results from a G2V star and which I describe fully at www.perseus.gr/Astro-Tips-G2V-Star-Calibr.htm . The weights I use are 1.531:1.000:1.279 for prime focus using the AP160. If any change is done to the optical train (ex. a 2x Barlow), the calibration must be redone.

3. Where do the diffraction spikes come from?

I used a couple of strings perpendicular to each other and attached to the dew shield. As a result, the horizontal/vertical spikes you see are due to this contraption. I expanded the spike pattern by adding another two spikes at 45-degree angles using Photoshop (there is a brush tool for this).

As for the latter - the artificial spikes - it is something that is very commonly employed by some of the biggest names in the world of astrophotography to great effect and is something which I like as well. A couple of people I have asked locally have expressed mixed feelings about the 'enhanced' spikes. Any thoughts?
Anthony Ayiomamitis
Athens, Greece
www.perseus.gr
15 years 2 months ago #33168

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I hear you on the flats - still, with your combination I'd assume that good flats would offer only a minor improvement.

The RGB article is very good!

As for the spikes - I'm really not sure. I'd have to see the image without the spikes to express a preference. That said, I think the spikes look good and give the image a sense of movement and life.

I think we're onto a winner :wink:
15 years 2 months ago #33169

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Replied by Seanie_Morris on topic Re: September Competition Theme - Star Clusters

I'm monitoring this very closely...

:lol: :lol: :lol:
Midlands Astronomy Club.
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Former IFAS Chairperson and Secretary.
15 years 2 months ago #33172

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Replied by ayiomamitis on topic Re: September Competition Theme - Star Clusters

I'm monitoring this very closely...

To follow-up, Dave, the photo was taken with my Tasco 60mm refractor and at 675x during average seeing. A firm tripod allowed for the simultaneous mounting of my one-time use and throw away camera. The flash was used to produce the beautiful spikes around the brighter stars.
Anthony Ayiomamitis
Athens, Greece
www.perseus.gr
15 years 2 months ago #33178

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And didn't Spectra Photo do a good job of the film processing?

Just so you know, when I scanned it here in Celbridge before mailing it to you, I made sure I cleaned the scanner glass with a bit of spit and paper towels. Worked a treat!
15 years 2 months ago #33181

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Replied by Seanie_Morris on topic Re: September Competition Theme - Star Clusters

Don't make me enforce a ban on the pair of you... just for the hell of it! :P
Midlands Astronomy Club.
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15 years 2 months ago #33183

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15 years 2 months ago #33184

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Replied by ayiomamitis on topic Re: September Competition Theme - Star Clusters

Dave,

Thanks for the scans ... I managed to remove the odd dust mote and proceeded with an LRGB combine. I hope you approve of our final result: www.perseus.gr/Astro-DSO-NGC-0457.htm . :?
Anthony Ayiomamitis
Athens, Greece
www.perseus.gr
15 years 2 months ago #33226

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Replied by Seanie_Morris on topic Re: September Competition Theme - Star Clusters

That is an absolutely beautiful picture Anthony (and Dave :P). I will say though that the only 'fault' I can initially see is the tiniest apparition of trailing from top right to bottom left corners.

I love the twinkle effects, especiialy as it is diffracted!
Midlands Astronomy Club.
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Former IFAS Chairperson and Secretary.
15 years 2 months ago #33228

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Replied by ayiomamitis on topic Re: September Competition Theme - Star Clusters

Hi Seanie,

I am glad you like the result!

Please note that it is not trailing you are seeing ... honestly! This is a VERY rich star field and there are countless doubles/binaries which give the false illusion that there is trailing when, in reality, there is overlap in the disks.

I did have some wind last night but I do not think (and hope) it impacted the result.
Anthony Ayiomamitis
Athens, Greece
www.perseus.gr
15 years 2 months ago #33230

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Replied by ayiomamitis on topic Re: September Competition Theme - Star Clusters

Seanie,

I just loaded my full-blown version into Photoshop and I honestly cannot believe how rich the star field is and the MANY faint stars being captured left, right and center!

The resampling (50%) perhaps may be giving the impression that there is some trailing when faint and the very small stars are reduced further by the resampling.
Anthony Ayiomamitis
Athens, Greece
www.perseus.gr
15 years 2 months ago #33231

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Replied by ayiomamitis on topic Re: September Competition Theme - Star Clusters

Seanie,

I tried using AIP4Win (V1.4) to count the number of stars and the program overflowed (too many stars?). I then went to Registar and found over 910 stars. I also checked the FWHM and it is around 1.5"/pixel which means really good seeing!
Anthony Ayiomamitis
Athens, Greece
www.perseus.gr
15 years 2 months ago #33232

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Replied by Seanie_Morris on topic Re: September Competition Theme - Star Clusters

Glad you counted them Anthony - I certainly wasn't going to!

I wonder if I could use that as a theme... see who can take the most (proven) star field shot.... I wonder.... 8)
Midlands Astronomy Club.
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Former IFAS Chairperson and Secretary.
15 years 2 months ago #33240

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Replied by ayiomamitis on topic Re: September Competition Theme - Star Clusters

I wonder if I could use that as a theme... see who can take the most (proven) star field shot.... I wonder.... 8)

Oh oh. I see all of us flying to the equator for a shot at the mother of all globular star clusters and which covers the equivalent width of the full moon! :lol:
Anthony Ayiomamitis
Athens, Greece
www.perseus.gr
15 years 2 months ago #33241

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