First Astro Photograph

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First Astro Photograph

Postby Russ.Carpenter » Sun Aug 10, 2014 10:38 pm

I was an earnest amateur astronomer 30 years ago and just returned to the hobby. Everything about it is better.

This is my first astro photograph. As a means of learning the ins and outs of StarTools, I decided to make it difficult. The subject, NGC7184, is relatively small and faint. I used just four frames and 19 minutes of imaging. 10 minutes of luminance and 3 minutes each of red, green and blue.

Of course, noise is the major issue. As I fiddled with StarTools I came to realize that the sooner one copes with noise, the better. Otherwise, wonderful tools like Wipe are dealt a fatal blow.

At the moment, I know of only three ways to address noise early in the workflow: RGB Blur, Ignore Fine Detail, and Dark Anomaly Filter. If there are other ways, I would love to know them.

I tried both the “standard” LRGB workflow and the synthetic luminance workflow. The second was clearly better. I’m sure that my photo has many flaws, but it certainly was a good learning experience.

I took the photograph with an iTelescope system in Siding Spring, Australia. These telescopes are high quality, and therefore the hourly rate can be fairly steep. Anything that can shorten imaging time is greatly appreciated. Which gets us right back to the issue of how to make sure that one uses StarTools as effectively as possible in reducing noise early in the process.

I hope you don’t mind if I put in a little plug for Mac computers. I use a MacBook Pro with Retina display. It has 16 Gb of RAM, a solid state drive, and a superb display. It seems just right for astro photography. These days, MacBook Pros are all over the place. I just got home from a trip and spent time in the San Francisco airport. There was the usual forest of laptops. Amazingly, every one of them was made by Apple. Thus, the promised upgrade of the Mac version of StarTools seems like a really good idea.

Russ Carpenter
Russ Carpenter
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Re: First Astro Photograph

Postby ancienteyes » Tue Aug 12, 2014 3:35 pm

Hi Russ!

As a rank novice, I'm reluctant to give any advice at all. I've only been imaging for 8 months now. And a Star Tools user for less than that.
But if there is one fundamental lesson I have learned, it's the more time you spend gathering data, the less post-processing you will need to do.

In particular, with lots of good signal, noise will often be so minimal, you can skip using NR algorithms entirely, thus preserving sharpness and detail.
Even a powerful program like Star Tools, can only do so much when working with data that has a low S/N content.
Looking at your image, I can only imagine what you would have had with, say, triple the integration time. It would be especially impressive given your access to high-end equipment.
You have a great start with that image; it's begging for more photons!

I have attached a shot I took of M16. It is a OSC (DSLR) image with only 2.5 hours of integration. The details are just starting to come in. With more time it could only get better, not to mention being much easier to process.

Regards,

ancienteyes :
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Re: First Astro Photograph

Postby Russ.Carpenter » Wed Aug 13, 2014 2:24 am

Hi ancienteyes,

Thanks for your comment and your willingness to help a newcomer.

In the case of a world-wide network of remote controlled telescopes, you don’t need to compromise on dark skies, excellence of equipment, variety of telescopes, suitability of the weather or even choice of hemispheres. But most of us do need to compromise on imaging time, because otherwise it can get pretty expensive. For example, the best telescope at Siding Spring costs more than $300 per hour. Your two and a half hours of integration would run around $750, which is kind of steep for an evening’s entertainment.

So the game becomes getting the best possible result within an affordable amount of imaging time. Inevitably, along with short imaging times comes noise.

That’s why I’m motivated to learn how to use the noise tools in StarTools as effectively as possible, especially the ones that are applied at the beginning of the workflow. As long as I stick with remote telescopes, I’ll need to use those tools a lot.

Best regards,

Russ Carpenter
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Re: First Astro Photograph

Postby admin » Fri Aug 15, 2014 12:20 am

Hi Russ,

Welcome back to the hobby!
Indeed, much has changed, and almost all of it for the better. :)

Noise is the bane of the astrophotographers's existence and dealing with *aspects* of it early on is indeed the best strategy. These aspects, however, are mostly acquisition and pre-processing related (e.g. stacking, debayering, color balancing and compositing related), rather than post-processing related.

You're right that it is generally the case that the lower the noise, the better StarTools' modules can get a handle on the true signal/detail in your image, just like a human would. Uniquely, however, StarTools is constantly battling the noise in the background on your behalf with its Tracking abilities - constantly pin-pointing its evolution as the various modules bring it out, and also constantly feeding back this data the modules so they know where to back off or where they can be be more aggressive. When it comes down to it, almost every module deals with noise in one way or another, since virtually any operation (bar simple operations like cropping or rotating) will alter the noise characteristics.

Wipe is indeed susceptible to anomalous 'dark noise', so filtering this out with the Dark Anomaly filter is usually a good idea. Beyond that, let Tracking do the heavy lifting and perform your final noise reduction at the end (by switching Tracking off). You'll notice it will be much less aggressive in parts of the image where it was able to find a good SNR, versus parts where the SNR was poor.

When working with high-noise data that contain non-field filling objects (like the galaxy in your image), you may be interested in the Life module's Isolate preset (preferably used with a full mask). It gives priority to larger scale objects and 'pushes' back smaller detail (such as noise or busy star fields) that is not embedded in the larger scale structures.

Your plug for MacOSX is noted; we've commenced an overhaul of the cross-platform development kit that ST is based on, which, amongst exciting other things, should bring MacOSX support up to scratch. I cannot give an ETA on this, as it's a considerable task.

Clear skies!

Russ.Carpenter wrote:I was an earnest amateur astronomer 30 years ago and just returned to the hobby. Everything about it is better.

This is my first astro photograph. As a means of learning the ins and outs of StarTools, I decided to make it difficult. The subject, NGC7184, is relatively small and faint. I used just four frames and 19 minutes of imaging. 10 minutes of luminance and 3 minutes each of red, green and blue.

Of course, noise is the major issue. As I fiddled with StarTools I came to realize that the sooner one copes with noise, the better. Otherwise, wonderful tools like Wipe are dealt a fatal blow.

At the moment, I know of only three ways to address noise early in the workflow: RGB Blur, Ignore Fine Detail, and Dark Anomaly Filter. If there are other ways, I would love to know them.

I tried both the “standard” LRGB workflow and the synthetic luminance workflow. The second was clearly better. I’m sure that my photo has many flaws, but it certainly was a good learning experience.

I took the photograph with an iTelescope system in Siding Spring, Australia. These telescopes are high quality, and therefore the hourly rate can be fairly steep. Anything that can shorten imaging time is greatly appreciated. Which gets us right back to the issue of how to make sure that one uses StarTools as effectively as possible in reducing noise early in the process.

I hope you don’t mind if I put in a little plug for Mac computers. I use a MacBook Pro with Retina display. It has 16 Gb of RAM, a solid state drive, and a superb display. It seems just right for astro photography. These days, MacBook Pros are all over the place. I just got home from a trip and spent time in the San Francisco airport. There was the usual forest of laptops. Amazingly, every one of them was made by Apple. Thus, the promised upgrade of the Mac version of StarTools seems like a really good idea.

Russ Carpenter
Russ Carpenter
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Re: First Astro Photograph

Postby Russ.Carpenter » Fri Aug 15, 2014 11:52 pm

Ivo,

Thanks for your comments. Your postings are always thoughtful and I really appreciate all the hard work you do for StarTools.

Russ Carpenter
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