What I Don't Know About Image Processing...

... can fill a warehouse.

I revisited my earlier M42, M3 and M51 image sets to give them another go around in software.

As it turns out, there's a lot more detail in there which I simply don't know how to extract.

These images are the results of my experiments.  I included both the old and new for comparison.

M42

First pass

Second pass

M3

First pass

Second pass

M51

First pass

Second pass

For each of them, more noise is apparent.  This isn't surprising giving how the image data is being stretched.  These image sets have bias frames applied against them, but no flat frames.

In each of them, I had to brush out dust mote imprints and subtract vignetting in Photoshop as a postprocessing step.  I'd like to try minimize this by pre-processing the raw frames with flat field images. I haven't taken any of those yet.

The two biggest changes I made in processing these images was to:

1. Not overdo the levels stretching.  Watch that histogram closely.  It's more important to get a nice bell-ish curve going (depending on the image) than to try make your background deep and your stars pop. The moment any "blackening" or "popping" occurs, you've probably lost data.
2. Curves!!!  Holy smokes, this made a big difference!  Being able to recognize what you want to draw out, and then manipulate the curves to reflect it, has had the biggest impact.  The same rules with stretching the levels applies.  Avoid any clipping (if reasonable) so cores aren't blown out and faint stars aren't lost.

The Orion Nebula - Redux

If a particular DSO can be considered a cliché, M42 is probably it.... but, frankly, I wait all year for The Great Nebula in Orion to appear in my skies.    It can be seen with the naked eye, it's a staggering sight in any telescope of reasonable aperture, and it's an easy target for imaging!

It's a pity it only appears (high enough) in mid-winter.

I couldn't let this winter go by without taking a picture of it with my C6-NGT.  My last shots of Orion were with my Meade ETX 125.  While they weren't horrific, they also weren't great.

Suffice to say, my first attempt at imaging M42 with my C6-NGT went vastly better.  I wouldn't classify this image as "fabulous" (not by a long shot), but for a beginner I would certainly call it "great".

Messier 42 (NGC 1976) - The Great Nebula in Orion

There's a lot wrong with this image, from the ever-present coma, to the overexposed and blasted out trapezium and the lack of whispy volume as the nebula fans out across space.

However, I'm also getting more comfortable with my hardware and software.  Nebulosity by Stark Labs along with tutorials and guidance from sources like the Astronomy Shed on YouTube, the Astronomy Forum and Cloudy Nights has been invaluable.  I learn something new every time I take a picture.

This outing has convinced me that an autoguider would be a very useful addition to my toolkit.  So,  I've picked up the Magnificent Mini Autoguider package from Orion Telescopes and Binoculars.  The included guide scope should work well with the newt, but my mak's 1900mm focal length is likely too much.

The Mak and the CG-5

Since getting the Meade ETX 125, I'd wanted to try take photos of the sky using it.  When I got the C6-NGT, I suddenly had a good mount to try it!

Since the ETX 125 OTA already has a mounting block with dual 1/4-20 holes in it, I just had to find an adapter to marry the scope to the CG-5.  Luckily, ScopeStuff sells just the thing!

Given how much slower the Meade mak (f/15) is to the Celestron newt (f/5), it's not a surprise that the images produced by the mak were much "dimmer".  All things equal, from the camera's perspective (exposure length, ISO), the C6 produced much brighter images.

What I don't recall, and what will necessitate another trip out with the mak, is how much coma was present.

My first shot with the mak and CG-5 was Albireo:

Albireo - Double star in Cygnus

I don't have a good grip on photographing stars yet.

My second shot was a single frame of M57:

Messier 57 - Planetary nebula in Lyra

As an experiment, I decided to do a comparison between a 30 second exposure and a 60 second exposure with all other things being equal:

Messier 57 - Planetary nebula in Lyra

Once I get an autoguider, I'd like to try thing experiment again, bumping up the exposure time incrementally to see how things are affected.

The C6-NGT and Astrophotography Take 2

On this night I decided to try image two targets.  One that I could clearly see with the telescope and another that I couldn't.

This round, two things were different:

1. I spent the time ensuring I had a better alignment.  It took a great deal longer, but the results blew away my first shoddy attempts at taking pictures with this gear.  Instead of doing a simple two-star alignment with an additional calibration star, I did a two-star with several calibration stars AND I performed Celestron's All-Star Polar Alignment routine.
   
   Assuming the All-Star routine really works (which is evidently does), it's really amazing how far off my mount was in pointing to the north celestial pole.  I don't have a polar axis scope, and given other amateur astronomers feedback on the All-Star routine it looks like I may not really need it!
   
   On a good night, the alignment routine will take me 15 minutes.  This is a far cry from the 45min+ needed for a good drift alignment.  I also assume it's not as accurate as a carefully applied drift alignment.  Regardless, the All-Star routine gave me one minute exposures with virtually no trailing.  Maybe I was just lucky!
2. I bought a bahtinov mask from Farpoint Astro.  This took all the guesswork out of focusing and as far as I'm concerned, is a cheap no-brainer accessory to add to your imaging toolkit.  I couldn't imagine focusing without it.  I first tried to make my own, but I eventually decided that $18 bought me a piece of equipment vastly superior to what I could make.

The Easy Target

M92, a globular cluster in Hercules is nice and bright in the eyepiece.  You can easily see it in a short exposure and is therefore easy to locate and center.  You don't have to spend hours imaging and processing to discover that your target is being clipped accidentally.

M92 - Globular cluster in Hercules.  4 x 30"

The alignment is definitely better, with little to no trailing.  However, evidence of coma clearly shows around the edges of the image.  Darn newt.  Well, maybe when I get better at this I can look into a coma corrector.

The Hard Target (for me)

Caldwell 34 -- the Veil Nebula in Cygnus -- is a DSO I can't see from my home with my telescopes, although I have seen it in my 10" newt at a dark(er) site.

I only took one sub of the Western Veil (30 seconds at ISO800) and at first glance I could see nothing...

C34 - Veil Nebula in Cygnus

... but it's there!  This was my first face-to-face with a DSO that would need more subs, a longer exposure and heavier processing to draw out the details.

Here's a Photoshopped version of the same image to help draw out the nebula:

The C6-NGT's First Terrible Pictures

A couple of days after I took my brandy new C6-NGT out for first light, I decided to try hook up my DSLR to it.  The first series of pics weren't great, entirely due to a hasty and beginner's alignment.  The exposures were about 30 seconds each.

My first shot was of M13, a globular cluster in Hercules.

M13 - Globular cluster in Hercules

Compared to my first shot of M13 using the MallinCam, this image's detail is much higher, but trailing is clearly visible from a lousy equatorial alignment.  I was still quite excited about my first shot, though, on a real equatorial platform.

I then decided to slew over to M57 in Lyra.

M57 - Planetary nebula in Lyra

Just like the first shot of M13, field rotation from a bad alignment is obvious; even more so in this picture... I wonder if I bumped the mount after my first imaging of M13.  However, the color from this picture was great.

Overall, I was quite satisfied and excited about my first outing with a more capable beginners imaging set up!

Poconos and the XT10i

The Orion XT10i is a marvelous performer under many skies, but during a week-long vacation I was amazed at the difference between the North East Philly sky and those found only 3 hours north around the Poconos and Greentown, PA (Promised Land State Park).

On this night the Wild Duck open cluster (M11) was incredible.

The contrast of the DSO's virtually exploded in my eyeball (in a good way), and things I had only seen faintly before (like M51 - Whirlpool Galaxy) or not at all (like C34 - Veil Nebula), were RIGHT THERE!  Clear as day! (So to speak.)  Globular clusters resolved with thousands more stars and the milky way appeared (dimly) crossing the sky.

This was around the time I decided I had to try astrophotography with a more capable set up than my Meade ETX 125.

The Orion Nebula and the ETX

Ever since I got my Meade ETX 125 as a quick(er) grab 'n' go scope for camping and other traveling excursions I'd wanted to try shift the mount into equatorial mode so I could take a few longer exposure pics.  A nice bright target was available, M42, which can readily be captured with a relatively short long exposure.

Speaking of camping with the ETX, here's a quick diversionary picture of the ETX in camping mode:

The time of day here is actually around 8pm.  The camera did a great job of lightening the scene.  The only problem with astronomy and state parks (I think this was French Creek State Park in Pennsylvania) is that there are a lot of trees.

My first attempt at DSO photography with my Meade was pretty rough.  While the mount is able to shift into an equatorial configuration, you can tell that it doesn't really want to and is much happier as an alt-az mount.

Using approximations and trial and error, you adjust the mount plate to your current latitude, orient the scope as described in the manual, switch the hand controller to Polar mode and align just as you would in alt-az mode.

All things given, tracking in polar mode is great.  After slewing to the target, the mount then only uses one motor to keep track of the object.  One the plus side, for visual use, the object stays in the viewfinder for a good long time.  On the negative side, the standard eye piece sometimes gets into awkward positions.  On the other hand, if you're using the visual back, the scope can't slew to everything it would like to since the diagonal would hit the mount.

Despite tracking being better in polar mode, it's still not really good enough for astrophotography.  The mount simply isn't built for it.

First Attempt

Here's my first image of M42 using the ETX in polar mode with my Canon Digital Rebel hanging off the visual back:

Elongated stars point to a crummy alignment, but look at that color!  After using the MallinCam, even this blurry image was tremendous.  This was about five 30" frames processed using Registax, then post-processed using Photoshop.

Second Attempt

The alignment this time was a vast improvement over my second attempt, and I dare say this image is quite decent for a beginner!

Apart from my alignment being much better, I pushed up the ISO of the camera.  The image is definitely grainier, but there's also a lot more detail.

The LX200 and MallinCam Experiment - M57

Messier 57 was my second attempt at astrophotography.  This DSO is Relatively bright and well within reach of the Meade LX200 I was lucky enough to have access to.

Messier 57 (NGC 6720) - Ring Nebula

At this point in my experience, I didn't know whether to expect color in my photographs, but as it turns out, this particular MallinCam couldn't do long enough exposures to get any color.  I forget exactly how many frames this particular video was, but probably several thousand.  Stacked with Registax and then roughly processed in Photoshop.