Staunton River State Park, an IDA Dark Sky Park in our backyard

September 21, 2015

The Charlotte Observer and Raleigh News and Observer just published my article about the latest IDA Dark Sky Park, Staunton River State Park. This new Silver-tiered Dark Sky Park is a fantastic resource to all those in the region. Make a trip up to view their skies, they are well worth it! 

http://www.charlotteobserver.com/news/science-technology/article35431416.html

Hopefully it helps, even just a little, to bring some more awareness to the preservation of our dark skies!
 
The IDA re-posted my article on their Facebook and Twitter: 

Some kind words about Staunton River State Park, one of the newest IDA Dark Sky Parks, by the N.C. Museum of Natural...

Posted by International Dark-Sky Association on Monday, September 21, 2015
 

Comparing NB filters

October 27, 2014  •  1 Comment

I just recently got a great deal on a couple Astrodon 3nm filters (H-alpha and OIII) which I am very excited about. I have had 12nm filters for a while now (Astronomik), which I have loved and are great filters, but I have always wanted to get some narrower wavelength filters for all the narrowband I tend to image. Cutting out extraneous light should greatly improve the signal I am getting in my images as well as allowing me to image a bit further into moon's cycle. While I plan on comparing these for a while during various conditions and will do additional writeups with photos, I got to image through the new filters for the first time at the Staunton River Star Party this past week and was mightily impressed with the 3nm filters.

I did some initial comparisons using Messier 16, the Eagle Nebula, the last evening out. The skies there were lovely (Sky Quality Meter (SQM) reading of 21.08 that night) and we were doing a public observing night as well, which gave an opportunity to introduce imaging and astronomy to adults and kids alike. I decided on 10 min exposures for all 4 filters and refocused between each filter with the Moonight Focuser. This time around I did not do a whole lot to compare, as I wanted to get onto my proper imaging for the night as it was the light night of the Star Party and the skies were so great, so I will do much better testing soon with many more #s and calculations, and exposure times.

To start, here is the setup and details for these comparisons:

Imaging scope: Orion EON80ED
Camera: Atik 314L+
Filters: Astronomik Ha 12nm, Astronomik OIII 12nm, Astrodon Ha 3nm, Astrodon OIII 3nm
Exposure time: 600s
bin: 1
Calibration: Darks and Flats

Location: Staunton River State Park, Virginia
Sky Quality Meter reading: 21.08
Date: 25 November 2014 

To start off, Hydrogen-Alpha 600 second single sub, unstretched comparison

Ha-1Ha-1 At first glance, the stars appear slightly larger in the 12nm as well as the overall background levels are higher (mean pixel stat value of 709 vs 540), although with a single unstretched sub it is hard to tell whether there is will be a noticeable difference in the nebulosity and overall image but it does appear as if there is more in the image already. With that said, on to stretching. 

For the stretches I used only levels and curves and as opposed to doing identical stretches with the levels on both (which would have resulted with a much brighter/washed out image with the 12nm due to the extra light let in), I adjusted the levels to keep the background of both images comparable and any curves I used, I did identically on both. I determined this would be the fairest way to compare the final results in the filters.  Ha-2Ha-2

After the stretches, the difference is very noticeable. While the physical size of the stars is similar (with the 12nm only being slightly larger), the brightness of the stars (especially the fainter stars) is noticeably less. Stretching to similar overall background levels brings out much more nebulosity in the 3nm filter vs the 12nm even though the exposure times were identical. The amount of nebulosity that is shown in a single 10 min exposure without having to do extreme stretching and risk introducing extra noise and without having to worry about stars bloating was just amazing.

I really wanted to see just how much was in there by having cut all the other wavelengths out so I did an inverted image comparison for a portion of the image where I removed the stars and used ONLY levels to do a linear stretch. Here is the result: 

Ha-invertHa-invert

The difference in contrast and extent of nebulosity between the two filters was quite impressive on this single exposure. While I cannot fault the Astronomik 12nm filter as I have gotten great results out of it, the narrower passband of the Astrodon 3nm just shows the advantages of going narrower. 

I also did the same comparisons with the OIII filters, here are those images:

OIII-1OIII-1

The initial star difference in the single unstretched sub is the main thing that is noticeable in this comparison, now on to the stretch:

OIII-2OIII-2

The comparison shows similar effects as the Ha: slightly smaller, although comparable, star size but with a noticeable difference in brightness for fainter stars creating the appearance of a less dense star field and increasing the nebulosity to star contrast, lower overall background light levels which allow for a higher nebulosity to background ration through. The result is more nebulosity, more contrast, and smaller-appearing/less bright.  stars. 

While I need to do more extensive comparisons, I am really impressed so far. I realize that the 3nm Ha filter will also cut out the NII line that the 12nm filter will allow through, which might be a reason to use the wider passband filter on certain targets. However, the advantages of the 3nm over the 12nm, despite the price jump, make it well worthwhile. 


Step by Step processing of the Orion Nebula

December 05, 2013  •  4 Comments

I have gotten several requests as to how I processed my latest M42. Before I go into that I want to mention that my processing of this was done using Adobe Photoshop CS5 and includes a few different processes layered together. This is snowballed a little by M42 and its high dynamic range from the core to the outer dust, which adds layering to avoid blowing out the core.

I will include photos as I go so you can see how the steps progress. I started with several stacks as I took multiple exposure lengths. I took 5 different sets and ended up making 2 master stacks: one for the core with the 60s and 120s exposures, one with the 480s, 600s, and the 900s exposures for the rest. I would normally use each set as its own process and layer the 5 together but started with the two to try to save time and it turned out well so didn't go back and do the individual stack processes.

Here are the two master stacks:

Core Stack
Long Exposure Stack

I started with a process of the core stack. I didn't focus on stretching it too much as I was just going for the detail in the core as the other stack would cover all the rest of the detail. A few levels, curves, and the enhance dust lanes action from my set and here is the final core stretch:

I saved this and then pulled up the long exposure stack and for the first run-through on it I removed the stars (action in the set) and some additional fine tuning using the clone tool for the brighter stars resulting in a starless main stack. I also ran GradientXTerminator for the image as I had a little bit of gradient showing from shooting in the south where there is a town about 15 miles away:
From here I ran the Channel Process action followed by a couple small manual rounds of curves, as well as the dust & scratches filter to take care of a few of the star remnants that pop up when you stretch which left me here:
I opened up the Color Efex Pro plugin and used the Detail Extractor as well as the Color Contrast Range selections which brought out a good bit of the dust. I did a little additional touchup with Dust & Scratches and the clone tool for the star remnants again (especially for the two larger stars just at the bottom on M42): 
The colors were beginning to get a bit muted so I did some selective color boosting to bring out the reds that had gotten dulled down when I balanced the background with GradientXTerminator:
I ran my Enhance Dust lanes action and then pulled the image back into Color Efex Pro and did a mild Detail Extractor along with Tonal Contast and Pro Contrast: 
Now I opened the original stack and began processing with the Channel Process action and the GradientXTerminator plugin (basically started the processing the same way I did with the starless version):
I ran Enhance Dust Lanes and some selective color boosting via Match Color (Image>Adjustments). To do this I used the lasso tool, feathered, on the two nebulas individually so I could customize each one a little better. After this I ran the Reduce Star Size action followed by Boost Star Colors. I then did a small amount of curves:
Now I brought the starless processing up and made it a layer on top of the starred semi-process and set the blending mode to lighten to bring through the stretched dust of the starless version and the stretched stars of the lower layer. I pulled up the lens correction filter and used it to counter some of the coma I had from forgetting to use my field flattener. I cropped as well just a small bit to focus the attention more on the nebula and the immediate surrounding dust: 
I did a little more color boosting with Match Color and the Brighten Color & Sharpen action and used some layered contrasting on the dust. This helped to make the browns in the dust pop compared to the background and the colors and details in the nebula to show up a bit better:
Now I opened up the core processing and layered it into the core section of M42 (using this method) to show the detail of the core in the parts that got blown out in the longer exposure stretching. I toned down the blue a little around M43 as well since the previous color boost had made it a bit more of a focus than M42. Finally I ran the star color boosting action and ran Noise Ninja on the image to produce the final image: 
Here is a larger version of the final image: 
 
 
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