Astronomy Tools - USD $21.95 Super Value! Carboni's actions, a popular, easy to use set of tools for Adobe Photoshop® (full version) designed for use by astrophotographers in all parts of image processing. Beginners to advanced amateurs and pros, polish up your astrophotos for a beautiful, natural-looking presentation. Hence Astronomy Tools were born. Beginners: Ever shoot your own images of the night sky, then find yourself wondering how other astrophotographers make such breathtaking images while yours don't seem to have quite the same sparkle or magic? Chances are they do more digital editing of their images than you think. Astrophotography by Noel Carboni On this page you'll find some of the astrophotos I've taken. Unless otherwise noted, these images were captured with my Canon EOS digital cameras or Meade Lunar/Planetary Imager and Meade 10' LX200 GPS UHTC 2500mm f/10 telescope from my light-polluted south Florida home. Enterprise Astronomy & Photography. These are user-friendly tools for Photoshop that help beginners and advanced imagers alike in processing their astrophotographs. Detailed instructions are included and t here is also a 30 day money-back guarantee if you have problems and I cant help get you sorted out. Noel Carboni's Astro Tools for PhotoShop / Carboni's Astronomy Tools Carboni's Astronomy Tools by Noel Carboni's Astro Tools for PhotoShop. Some images (view more) IC 1318 HaRGB Ron Cygnus Wall Ron SH2-114 - Flying Dragon Nebula (HOO) Ron.
Unless otherwise noted, these images were captured with my Canon EOS digital cameras or Meade Lunar/Planetary Imager and Meade 10' LX200 GPS UHTC 2500mm f/10 telescope from my light-polluted south Florida home. I used my own Astronomy Tools actions, AstroFlat Pro plug-in, and StarSpikes Pro 4 plug-in on these images.
Click here to learn more about the astophotography software I've written to process astroimages:
My Astrophotography Software
My Latest Astrophotos
| Two Days Past a Super Moon, September 10, 2014 A Super Moon is when the moon happens to reach Full stage at the same time it's closest to the Earth, and so it looks large in the sky. This image was taken almost 2 days past the Full phase, and you can see the edge starting to fall in shadow at the upper-right. This image is a mosaic of 18 separate and overlapping 10 megapixel images from my Canon EOS-40D digital SLR set to M (manual) mode, captured as raw .CR2 files and converted and stitched together in Photoshop CC 2014.2. I mounted my dSLR to my Meade LX200 GPS UHTC 10' Schmidt-Cassegrain telescope via my 2x Televue Powermate - a focal length doubler, similar to a teleconverter, which also serves to mate the camera to the 2' telescope eyepiece tube. Effective focal length in this configuration is 5000mm f/20. Using Live View mode on the camera to frame the images, I swept across the surface in a zig-zag fashion, trying for about 1/3 to 1/2 overlap between frames. I triggered the shutter 8 times manually at each position with my TC80-N3 remote timer/controller, allowing the telescope to settle (stop vibrating) between shots. After I chose the sharpest image from each set, Photoshop CC's Photomerge feature made quick work of the stitching. Since it was taken at the camera's most noise-free setting (ISO 100), the data is highly accurate, and thus I was able to strongly increase the color saturation via Photoshop's Image - Adjust - Hue/Saturation function. Thus the colors are real, indicating different mineral compositions of the lunar surface. |
Previous Astrophotos
| The Moon in Hypersaturated Color Stacked from 15 exposures of 1/5 second at ISO 100 This image is a mosaic of 15 separate and slightly overlapping 8.2 megapixel images from my Canon EOS-20D (unmodified), taken in Raw mode and converted and stitched together in Photoshop CS2. The exposures were each 1/5 second at ISO 100. I mounted my 20D to my Meade LX200 GPS UHTC 10' Schmidt-Cassegrain telescope via my 2x Televue Powermate. Effective focal length was 5000mm f/20. Looking through the viewfinder I swept across the surface in a zig-zag fashion, trying for about 1/3 overlap between frames. I triggered the shutter with my TC80-N3 remote timer/controller. I did the stitching by hand in Photoshop. Since it was taken at the camera's most noise-free setting (ISO 100), the data is very accurate, and thus I was able to strongly increase the color saturation via Photoshop's Image - Adjust - Hue/Saturation function. APOD (Astronomy Picture of the Day), September 7, 2006: A high resolution 1600 x 1200 image with stars added, makes a great desktop background. |
| M45 - The Pleiades Cluster Stacked from every image I've taken of the Pleiades over a year and a half. I digitally combined all long and short, high and low focal length images I've ever taken of the seven sisters and came up with a result better than that from any individual set of images. |
| M57 - The Ring Nebula Stacked from every image I've taken of the Ring Nebula over a year and a half. I digitally combined all long and short, high and low focal length images I've ever taken of M57 and came up with a result better than that from any individual set of images. |
| Polaris - the north star. Stacked from 16 exposures of 30 seconds at ISO 200 plus 14 exposures of 30 seconds at 1600 with 0.63x focal length reducer / field flattener and IDAS light pollution filter on my LX200 telescope. Shot in Raw mode and converted in Adobe Photoshop using -20% color saturation so as not to clip the black point. |
| M68 - Globular Cluster. Stacked from 34 exposures of 15 seconds at ISO 1600 with 0.63x focal length reducer / field flattener on my LX200 telescope. |
| M13 - Globular Cluster. Stacked from 30 exposures of 30 seconds at ISO 1600 at prime focus of my LX200 telescope. M13, also called the Great Globular Cluster in Hercules, is one of the best known globulars of the Northern hemisphere. This image isn't deep enough to show nearly all of the several hundred thousand stars in M13. |
| M43 Nebula. Stacked from 132 exposures of 20 seconds at ISO 1600 at prime focus of my LX200 telescope. M43 is the roundish nebula with the star in the center. Part of the M42, the Great Orion Nebula, also shows at the lower-right of the image. |
| M104 - The Sombrero Galaxy. Stacked from 30 exposures of 30 seconds at ISO 1600, some at prime focus and some using my 0.63x focal length reducer. Photographed at my dark site near Lake Okeechobee in Florida. |
| The Coma Bernices star cluster. Wide starfield shot stacked from 7 exposures of 2 minutes at ISO 3200, using my 100-400 zoom lens at 200mm piggybacked atop my LX200 telescope. Photographed at my dark site near Lake Okeechobee in Florida. |
| The Rosette Nebula. Stacked from 29 exposures of 2 minutes at ISO 3200, using my 100-400 zoom lens at 400mm piggybacked atop my LX200 telescope. Photographed at my dark site near Lake Okeechobee in Florida. Unfortunately, the deep red color of Hydrogen Alpha emission in this nebula is all but blocked by the unmodified Canon 20D's internal filters. |
| Wide field shot of NGC4559, NGC4565, NGC4494 in the Coma Berenices constellation. Stacked from 7 exposures of 2 minutes at ISO 3200, using my 100-400 zoom lens at 300mm piggybacked atop my LX200 telescope. Photographed at my dark site near Lake Okeechobee in Florida. Several galaxies and a globular cluster are visible. NGC4565 is an edge-on galaxy sometimes called 'The Needle Galaxy'. |
| Very wide shot of the Corvus constellation. Stacked from 3 exposures of 2 minutes at ISO 3200, using my 100-400 zoom lens at 100mm piggybacked atop my LX200 telescope. Photographed at my dark site near Lake Okeechobee in Florida. |
| The bright star Aldebaran and the Hyades open cluster. A wide starfield image, stacked from 11 exposures of 10 seconds at ISO 1600 using my 100-400 zoom lens at 200mm piggybacked atop my LX200 telescope. The Hyades cluster is very close to Earth and thus the stars are quite widely dispersed. |
| Wide starfield shot in Auriga, showing M36, M38, NGC1907. Stacked from 9 exposures of 10 seconds at ISO 800 using my 100-400 zoom lens piggybacked atop my LX200 telescope. |
| The Big Dipper asterism, part of the Ursa Major ('Great Bear') constellation in the northern sky. I shot this image by mounting my camera with 17-40 zoom lens at 31mm atop my telescope and using the mount to track the stars. As long as I keep the exposures fairly short, circular trailing is kept to a minimum even though I'm using the telescope in altitude-azimuth configuration for ease of setup. If you look carefully in the high resolution image, there are quite a few tiny deep sky objects (galaxies and nebulae) visible. |
| Orion the hunter. One of the most recognizable constellations in the winter sky. Another wide angle high resolution shot through my 17-40 zoom lens, which is proving to be a great performer for astrophotography. |
| Messier Objects 82 and 81 Wide Field. I shot this image by mounting my 20D with Canon 100-400 zoom lens at 300mm piggybacked on top of my telescope. If you look carefully in the high resolution image, there are a few galaxies besides M82 and M81 visible. |
| The Double Cluster, NGC 869 and NGC 884. Canon EOS-20D and Canon 100-400 zoom lens at 300mm, piggybacked on top of my telescope. |
| A high magnification image of the planet Saturn and five of its satellites. The upper atmosphere was moving around early on, but by about 10 PM it had really settled down. It was great looking at the moon and planets with super-high magnification through still air. About the time Saturn's Encke division showed in the eyepiece I figured I'd better break out the LPI and do some imaging. The optics in my LX200 continue to amaze me. There's some odd 3 point flaring when the scope is warm, but man when it cools down (to 65 degrees F in the case of last night) there just don't seem to be any limits! I was quite comfortable looking at Saturn with my 2x Powermate and 9mm Nagler... What's that, 556x? Amazing! Right at diffraction limits. |
| NGC 2392, the 'Eskimo Nebula' or sometimes known as the 'Clown Nebula', a 'planetary' type nebula so named because it is round and about the size of a planet. It's really the outer shell of a star not unlike our sun that's been blown off at the end of the star's life. Not long ago I decided I'd try to concentrate on photographing small, bright objects, insofar as I have a lot of light pollution here at my home, and I have a long focal length scope (10' LX200 GPS UHTC, 2500mm f/10) with great tracking. Thus, the 'Eskimo Nebula' seemed a good fit. I did some exposures of this object about a year prior, before I had a Powermate and knew much about processing. I decided I needed to do it better. This is stacked from 60 Canon 20D JPEG images at 15 seconds, ISO 1600 plus 55 Raw images at 20 seconds, ISO 3200 through my 2x Powermate, which made the telescope 5000mm f/20. Note that this is unguided in alt-az configuration. I took one dark frame to calibrate all images, and it greatly reduced hot pixels in both sets of shots. |
| M45 - The Pleiades, Wide Field. My second attempt at this cluster with my 20D and 100-400 zoom lens piggybacked on my telescope, this time from a site with darker skies. I was able to sustain 2 minute exposures at ISO 3200. The only thing keeping me from going deeper and getting a cleaner shot was that clouds moved in before I had finished the exposure set. |
| A closeup of the Trapezium region of M42. Stack of 242 exposures at ISO 200, 400, 800, 1600, and 3200 and various exposure times. |
| The Belt of Orion, Wide Field. A stack of 23 ISO 3200 images taken at a dark site, piggybacked through Canon 28-135 zoom lens @ 135mm, f/5.6, 1 minute per subexposure. In this image you can see the flame nebula and horsehead nebula area near Alnitak, the leftmost belt star in Orion. |
| M31 - The Andromeda Galaxy Most folks don't realize how large the Andromeda Galaxy is. It requires a wide-field setup - in my case a camera lens on my dSLR, piggybacked on my telescope to track the stars. Visible also in this shot are M32 (the small blob left and a bit up from the main galaxy's center), and M110 (the blob to the lower-right). Canon EOS 20D at ISO 1600 through Canon 100-400 zoom lens @ 300mm, f/5.6. 92 x 30 second subs stacked in Images Plus, and processed in Photoshop |
| The Sword of Orion I piggybacked my Canon 20D and 100-400 zoom lens on top of my LX200 and got this wide field shot. This is NGC1977 (the Running Man nebula), M43 (the little mostly round nebula), and M42 (the Great Orion Nebula), all making up the sword of Orion. Canon EOS 20D at ISO 1600 through Canon 100-400 zoom lens @ 300mm, f/5.6. 22 x 30 second subs stacked in Images Plus, and processed in Photoshop |
| Saturn 161 of the best frames of Saturn chosen by Meade Autostar software, taken with Meade LPI (Lunar/Planetary Imager) through Powermate 2x on Meade 10' LX200 GPS UHTC, stacked in Registax, upsampled in Photoshop, Adaptive Richardson-Lucy sharpening in Images Plus, color balance in Photoshop, final sharpening with my dSLR Fractal Sharpen actions. Moments of reasonably good seeing that night. |
| M45 - The Pleiades Piggyback my 100-400 lens on my LX200 - check! Tighten zoom ring so no slippage - check! Find best focus (not at infinity mark) - check! Determine max exposure time at 300mm f/5.6 - 30 sec ISO 1600, limited by LP. Took a bunch of exposures for half an hour before the battery died. The LX200 unguided alt-az tracking was great, at 300mm I was able to use EVERY SINGLE exposure in the stack; all had pinpoint stars and no trace of rotation. Woohoo! Problem is I could *BARELY* coax any nebulosity out of the resultant image. I got more out of two exposures during the power outage after the hurricane. I really need to get to a dark sky site for this one. |
| Mars When I got my LX200 almost a year ago, included in the package was the Meade Lunar Planetary Imager (LPI). I tried it out exactly once, but because I was having USB connector problems on my laptop I put it away and never tried it again. Until Now. Meade 10' LX200 with Televue Powermate 2x, Meade LPI, 41 frames chosen by the Meade Autostar software, stacked in Registax with wavelet enhancement, Adaptive Richardson-Lucy sharpening in Images Plus, final processing in Photoshop |
| Moon-Mars Conjunction, November 14, 2005. Single ISO 100 image taken handheld through Canon 100-400 zoom lens @ 380mm, f/5.6, 1/125 second. |
| Mars on November 8, 2005, just past opposition. Eyepiece projection for high magnification, stacked from 5 particularly sharp ISO 200 dSLR images out of a set of 45 exposures at 1/3 second each. Kind of like a webcam, but with far fewer frames. |
| NGC 1977, the 'Running Man' nebula in the sword of Orion, just up from the big, bright M42/M43 complex. Taken through my Meade f/6.3 focal length reducer, stacked from 10 ISO 3200 exposures of 30 seconds each. |
| APOD (Astronomy Picture of the Day), November 18, 2005. The answer to life, the universe, and everything... Douglas Adams was off by 5! NGC 2169, The '37' Cluster. 26 x 30 second ISO 3200 subs, with f/6.3 FL reducer. |
| Saturn, early in the morning of November 8th, 2005 (3:48 am EST to be exact). I captured 8 satellites, according to Cartes du Ciel, and a few stars too! With Televue 2x Powermate. This was a combination of 3 exposures, 0.4 sec at ISO 100, 10 sec at ISO 400, and 30 sec at ISO 3200. I overlaid the three exposures in Photoshop, then erased through the overexposed parts to combine the data and show much more dynamic range than the camera is capable of in any one exposure. Click here to see a medium resolution image. |
| Messier 42, the 'Great Orion Nebula', and Messier 43. A combination of a stack of 11 x 5 second ISO 3200 shots for the bright Trapezium area, and a stack of 19 x 30 second ISO 3200 shots for the rest. |
| The Moon and Venus, November 5, 2005. Shot at ISO 800 through my Canon 28-135 zoom lens @ 135mm, f/6.3, 3 seconds. The diffraction spikes are optical, from the aperture vanes. |
| A 60 degree wide-field shot showing Cassiopea, Andromeda, Pisces, Perseus, Triangulum, and Aries. The Andromeda galaxy, the Double Cluster, and several other DSOs are visible, as well as Mars in the lower-right. This was a single, non-tracking 30 second ISO 1600 shot with my Canon EOS-20D through my Canon 10-22 zoom @ 22mm. Taken on October 25, 2005, just after Hurricane Wilma blew out all the power and darkened the skies. Click here to see a medium resolution image. |
| An almost 90 degree ultra wide-field shot of the dark south Florida skies on October 25, 2005, just after Hurricane Wilma blew out all the power. We've never seen stars like this here before! Taken through my Canon 10-22 EF-S lens @ 10mm, 30 seconds, ISO 1600, f/3.5. Click here to see a medium resolution image. |
| NGC 869, one of the Double Cluster in Perseus. Just a very small image I prepared quickly for a photo contest. |
| Mars, on a background of stars. Combined from two stacks of exposures, one for the planet and one for the stars. |
| Albireo, a beautiful blue/yellow double star, taken as a test shot to determine the optical quality of a new TeleVue Powermate 2x lens I had purchased. This makes my Meade into a 5000mm f/20 scope. |
| The Moon. A 15 image ultra high resolution mosaic, stitched in Photoshop. Each sub-image was an ISO 100 shot through my Powermate 2x. |
| Messier 57, the Ring Nebula. Shot taken through Meade 0.63x focal length reducer / field flattener. |
| A combination of two exposure stacks, one for the planet and one for the background stars and moons. |
| M27 - The Dumbbell Nebula By coincidence, when I imaged this object there was a new star showing, which is highlighted with the two lines in the image. The forums were abuzz with talk about whether it was a supernova, a nova, or just a variable star. Most ended up agreeing it was a variable, but I didn't hear for sure, so I labeled it a nova in the image. 40 x 30 second ISO 3200 subs, Canon EOS-20D on Meade LX200 GPS UHTC 10', f/6.3 FL reducer, unguided, alt-az mount. Click here to see a medium resolution image. |
| Messier 37 - Open Cluster |
| Messier 36 - Open Cluster |
| Messier 35 - Open Cluster 3 x 30 second ISO 1600 subs at prime focus (2500mm f/10). |
| Several shots with different exposure parameters overlaid to capture both the Earthshine and sunlit portions. |
| A sequence of 7 images of the moon taken with my Canon EOS-20D and Canon 100-400 zoom lens. |
Click here to learn more about the astophotography software I've written to process astroimages:
My Astrophotography Software
All Content Copyright © 1995-2010 Noel Carboni
Current Astrophotography Capture Equipment
Advanced blending in Photoshop is discussed on my page here
Nikon D810A Capture and Image Processing Workflow
I have struggled a bit in finding a suitable image processing workflow with the Nikon D810A. Here's what I do right now, followed by a discussion of what did not work.
I shoot 5-minute RAW sub-exposures at ISO 400 using Backyard Nikon or the camera's built-in intervalometer. I take as many dark frames as I can at similar temperatures and the same ISO. I take flat frames (at least 12) using an EL panel at ISO 200, with the same aperture for the lights if using a camera lens. ImagesPlus and DigiCamControl also can control the Nikon D810A. I believe you may need to purchase a special module with IP.
I focus with a Bahtinov mask, usually just using live view image on the back of the camera (super convenient!)
I usually capture flats with an EL panel but I used sky flats on my Andromeda image from 2016 and they worked pretty well.
I use Deep Sky Stacker for 'reduction.' E.g., DSS manages the application of the flats and darks to produce a calibrated image. DSS now supports D810A .NEF files natively, which I didn't realize until recently. I was needlessly converting the .NEFs to .dngs.
Image stacking is with DSS (for sequential images of the same target if I'm feeling lazy) or with Registar. Registar handles mosaics much better than DSS, and is generally awesome.
DSS is the only software I have found that can properly apply flat frames, at least with the way I'm doing things. Flats were better with the telescope at f5.4 than with faster and wider-angle camera lenses.
I then process in Photoshop as discussed later on this page.
What did not work for the D810A?
ImagesPlus does not do a good job with flat-fielding for me. DSS does a good job with exactly the same images. The IP support people took a look at this problem and their best suggestion was that my flat frames are not similar enough in luminance for IP.
This page has a discussion of the flat-fielding problems with IP.
In fairness to IP, I tried flat-fielding with Nebulosity also with poor results.
In 2016 I processed some of my Andromeda Galaxy frames with IP and it was OK. So there's still a bit of mystery here.
Do you have a workflow for the D810A that produces good results? Please post to the D810A Yahoo Group!
My Image Capture and Processing Workflow with the SBIG ST-8300 Monochrome Camera with the FW8-8300 Filter Wheel & Astrodon 5nm 36mm filters
I shoot 5 minute images (sub-frames), and lots of dark frames (16-50) if possible. I also a shoot flat frames (8-32) with an EL panel, with each filter if time permits, but it looks like flat frames can be somewhat interchanged. The panel is shown on my 'other astro equipment' page. I make darks and flats on the same night as I shoot if clouds permit, but I avoid wasting time shooting darks and flats under clear skies.
I focus with each filter when using the fast focal ratio FSQ-85 scope. My Astrodon 36mm filters are supposed to be parfocal to f/4, however: a) my FSQ-85 is f3.86, and b) I wasted many hours of images by not focusing with different RGB filters; proving they are not reliably parfocal on my equipment. Having said that, there is almost always a temperature shift after an hour or so, meaning you should refocus frequently in any case for best results.
Focusing is accomplished manually with use of Bhatinov masks using the focus routines in MaximDL. The Bhatinov mask approach is simple, accurate, and highly recommended.
I switched to Maxim DL for image focus/capture and image reduction (flats fielding, dark frame subtraction) on the SBIG. Previously I used CCDSoft. CCDSoft is not being regularly updated in my opinion, and I had to go to a beta/daily build version of the software to use my filter wheel. Maxim's business is largely Maxim DL and they are much better at staying current with equipment. Software Bisque is focusing on a new package integrated into 'The Sky.'
I use Registar to stack each reduced FITS image of the same type object and framing. Where complex blending is needed, or when I'm going to turn a set of narrowband monochrome images into color, I align the different versions in Regisar, then use the Crop/Pad Image feature to make the images the same pixel dimensions.
I then copy and paste the monochrome images into my RBG color channel of choice to create a rough color image.
I will usually paste the H-Alpha image into the Luminosity channel in Lab mode, then then back that off to taste. I used the H-alpha version at about 50% in the red channel of my recent (2014) M8 & M20 area RGB H-alpha image here.
It's Photoshop CS6 from there as described below.
'Natural Color' Technique from Narrowband Images (RGB optional)
Here's a detailed description of how I processed my Lagoon Nebula natural color image (located here).
First I get each image aligned and processed so it's reasonably 'bright.' I used Registar to align each image, and padded each image to exactly the same size so I can do the remaining work in Photoshop.
I blended the narrowband images using the formula below. (I paste the narrowband data into the desired color channel with Photoshop, then fade the previous result based on the blending formula.)
I worked on the image with curves so it had a neutral background and nicely showed some color.
I added the RGB filtered data using Photosohop same as before, (fading the true color data to roughly set it to be the proper contribution based on the exposure time and judgment).
Once again, work on the image with curves looking for a neutral background and nice colors.
Towards the end, to deal with low-level noise, I blended in a modified version of the bright and smooth Ha data for luminance (e.g., paste Ha, sent blend mode to luminance, then fade that to maybe 25-33%).
I kept interim versions of everything to deal with blown-out highlights that resulted from enhancing the dim areas so they could be easily seen. Towards the end I went back, modified interim images to nicely show the highlights, and blended just the highlights in with layer masks.
Finally, I selectively blended in an interim image that helped enhance the contrast of the dark areas.
For Reference: I start with something similar to below, but then freelance... An approximation of natural colors may be achieved by the following narrowband blending:
Red = H-alpha + Sulfur II (approx 75% / 25%)
Green = Oxygen III
Blue = Oxygen III + H-alpha (approx 85% / 15%)
Another formula found on a PixInsight page says:
Red = 0.5*S2 + 0.5*Ha
Green = 0.15*Ha + 0.85*O3
Blue = O3
This is a popular color combination as well; I will create both Hubble Palette and Natural Color images from narrowband sub-frames in most cases.
Red - Sulfur
Green = Hydrogen Alpha
Blue = Oxygen
My Image Processing Workflow with the QHY8 'One Shot Color' Camera
I am using the recommended workflow in Nebulosity and then use Registar and Photoshop as outlined below:
Capture in Raw (using 5 minute sub exposures) in Nebulosity
As of late 2010 I need to fix Bad Columns and I'm using Sander Pool's fixfits utility. Update, 2011, by getting good bias and dark frames at very close to imaging temperatures my bad column issues are greatly reduced. In 2013 I am no longer using bias frames.
I previously used Nebulosity's Bad Pixel Map feature, but due to the bad column issue I'm using darks more often in 2013. I had two cloudy nights on a fall 2013 trip and took 150 darks for the trip, where all the nights had similar temperatures. The results combining the darks with a 1.75 sigma combine appear to be quite good.
Apply a Flat (which is done in the same step as using the dark)
Demosaic each image
Covert to Tiff format (I do this because Registar can't seem to handle the FITS files that Nebulosity puts out)
Stack using Registar
Process in Photoshop as noted below.
When using a H-alpha filter, I use the channel mixer to turn the image to monochrome using only the red channel. (See more info on narrowband filtering with this camera at the bottom of my Narrowband Imaging page.)
May, 2010: I sometimes use Deep Sky Stacker, Drizzle Image Processing, and AIP4Win's deconvolution filter to enhance the detail in dust lane areas.
DSLR Workflow
I still shoot (as of late 2012) astronomy images with a Digital Single Lens Reflex (D-SLR) camera, namely the Canon EOS 20Da. This camera has a modified design especially for astrophotography. I always shoot RAW format images.
I shoot 4 minute exposures at ISO 1600, now with a 15 second delay between exposures (instead of 45 seconds which I used before) to let the camera cool down a bit. Through 2007 I shot at ISO 800, but 1600 is best! Make sure your darks are at a matching ISO!
I am using ImagesPlus v. 2.82 to convert the Raw images from the 20Da, and for calibrating my images with a 'dark frame' and a 'flat frame.' I shoot darks while I'm changing targets, just getting them in here and there through the imaging session, and as I'm packing up. I then median combine the darks from the night and use them in my processing. I shoot flats during twilight, shooting about 16-20 and median combining them. (Update 11/2006, I am not currently using bias frames!) (Update 2013, I am gravitating towards a library of many darks from similar temperatures, rather than trying to get darks during the shooting night. I find that a very large # of combined darks works quite well. One thing to note is that the camera changes temperature as it starts shooting, seeming to stabilize after 30 minutes or so all else being equal. So, it's important to get darks capture during the same type of lengthy shooting scenario.)
In general, the dark frame is subtracted from each image frame, and the flat frame is calculated in to reduce vignetting. I'm using the IP workflow per the tutorial, but...
I often use Registar to combine images. Registar is easier to use than IP for images with different camera locations, and can handle radically different frames of the sky easily. Registar has a means to calibrate the levels of the combined frames that can work well for mosaics.
Then to Photoshop as noted below.
Photoshop rules for my final image processing.
I use Curves to manipulate the image.
I've started using the 'Standard Curve' in Photoshop as described in 'The New Astro Zone System for Astro Imaging' by Ron Wodaski and Russ Crowman. I saved one of these as an action I can run. After each run you need to set the black point in each color channel.
(Pre-2014) I have build an action that makes a series of small curve adjustments on the dark end of the image. The adjustments boost the low end but leave the stars end of things largely unchanged. I will run what amounts to around 10 small curve adjustments very rapidly to 'pull the image out of the muck' and get the image in a good, workable range.
NR: Aside from 'pulling the image out of the muck,' additional noise reduction techniques must be applied to most images image due to the extreme 'stretching' of typical astronomy images.
Noise reduction approaches: There several approaches/tools that can be used for noise reduction. Great results and ease of use are my top priorities. While some free tools may be available, I'm willing to pay for tools that meet my needs in this area. I use a couple of plug-ins. Neat Image is my favorite, and it is easiest to use when there is a fairly blank area of sky (no stars, galaxy, nebula, etc.) to select. I also use Grain Surgery in cases where I can't easily use Neat Image.
Aside: The best noise reduction in Photoshop alone (i.e., if you just using what comes with Photoshop) is based on strategic selection of areas to blur, with application the Gaussian blur. You can select a color range, or use the wand tool with a small # tolerance like 4. You can do this differently in each color channel.
Some images have issues with gradients, and I use and recommend the GradientXterminator plugin.
A few more (basic) details regarding what I do in Photoshop is at this link: Basic Image Processing in Photoshop.
Also, see the LAB curves technique I'm using, described below. This helps bring out the colors.
Star Shrinking: In 2012 or so I investing in Noel Carboni's 'Astronomy Tools' for Photoshop which was $22 very well-spent. Previously, in late 2008 I began to include star size management using a technique similar to the one on the top of this page.
The HDR toning feature in Photoshop CS5 & CS6 is useful for final color enhancements.
Star Selection
Astronomy Tools And Equipments
There are many ways to select stars and Noel Carboni's tools have an action that works well. The trick is to properly expand & feather the selection.
Tight stars? Expand about 3-4 pixels and feather about 50% of that.
Bloated stars? Expand up to 7 pixels and again feather around 50% of the expansion.
Photoshop Tip: LAB Curves can help add color to flat images
There are lots of ways to 'add color' to a flat DSLR astronomy image. A classic: apply an 'S' curve to the image. (Image->Adjustments->Curves, pull up the right/bright part of the curve, and pull down the left/dark part of the curve.) You can use Image->Adjust->Hue/Saturations, but purists shudder at this.
However, using this LAB technique has advantages as enumerated in Dan Margulis' books including 'Photoshop Lab Color' and 'Professional Photoshop.' It's pretty simple.
Convert Image into Lab. Alt-I-M-L gets you there (Image->Mode->Lab).
View the 'a' channel. Ctrl-2 gets you there. It will look very strange.
Here's a trick: Hit the ` key to the left of the # 1. This displays the image in color, but with a channel selected for any manipulations.
Bring up the curves function. Now, make the curve steeper, but keep the center point the same. The curve is a straight line. Do the same with the b Channel. See example below.
How far to go is a judgment call. If you'd like the subtly change the overall color balance, you can vary the line so it doesn't exactly cross the center point. Don't go too far with this!
Blur a/b channels? Other things you may wish to do in lab include blurring the a and b channels a bit, or maybe a lot, to help get rid of noise. This can help keep star colors under control (see caveats.)
Adjust the Luminosity channel. Be aware, thought, that pulling up the luminosity curve to better show the dim parts of your image will tend to flatten colors/reduce color saturation. (You can go back to step 4 again, if you want.)
Ctrl-' gets you back to all channels selected
Convert back to RGB. Alt-I-M-R gets you there.
Example: check my M31 page, including the images at the grid at the bottom of the page, showing where I started color-wise, and where I ended up.
Caveats: There are many, but the main caveat is that this best with images that are not already highly colorful. This technique also tends to exaggerate chromatic aberrations around stars, so this may need to be mitigated. (I should note that blurring the a/b channels in lab helps with this as described in step 6.)
Recent Update: The HDR toning feature in Photoshop CS5 & CS6 is a good alternative for adding color, especially for adding the finishing touches on a good image that could stand additional saturation.
Above: Adjusting the b channel by equal amounts. By making the curve steeper, you increase the visible differences between colors, increasing the color range of flat images.
Below Left: notice how flat this DSLR image seems; little color.
Below Right: Some color is starting to show after using the lab technique described here.
A starting point for the M31 images on this page: Pretty Flat! | 1st Cut 20Da image stack. 1200 pixels wide. Some Photoshop Lab processing to accentuate the color differences by steepening the 'a' and 'b' curves. |
| Excellent Photoshop Astro Techniques Link | Matt's Star Shaping |
| Selecting Stars | More Photoshop Tricks including shrinking stars |
Current Astrophotography Capture Equipment
Advanced blending in Photoshop is discussed on my page here.
Copyright © by Dick Locke. All Rights Reserved. Last update: October 2013
Contact and Image Use Information
hits.
As of 2012 I tend to use Noel Carboni's Photoshop actions to select and shrink stars.
For Reference: Wei-Ho's star subtraction technique
Neil Carboni Astronomy Tools
Instead of (de)selecting stars, what I do is to subtract stars, enhance
everything else, and then add the stars back. Stars can be subtracted
using a high-pass filter. The basic steps are like this:
1. duplicate the image
2. high-pass filter the dup, with a radius about 4-10 times the size of
the faintest stars.
3. level the high-passed image. Change the lower input level from 0
to 128, and the higher output level from 255 to 128.
4. subtract this high-passed, leveled dup from the original.
5. enhance the star-subtracted nebula image
6. add back the high-passed, leveled dup.
There are several variations. For example, you can very easily
select the non-stellar components in the product of step 3, set
the background to black, then push the 'delete' key. This will
prevent nebula components being subtracted in step 4. You can
also do more than two times of star subtractions with increasing
radii in the high-pass filtering. This will get rid of stars more cleanly.
Color Processing DSLR & CCD Astrophoto Images- different than film? (Yes...)
Noel Carboni 60s Astronomy Tools For Sale
I've often thought that DSLR and CCD images seem relatively flat and monochromatic when compared with the film images from back in the old days This is true especially in the reds, where DSLRs generally have a relatively weak deep red channel. Popular astrophotography films have had a strong red response, including Kodak's PJ400, LE 400, and Supra 400 (all out of production), as well as Kodak E200 and Fuji's SHQ 200. A reason red is so important: Hydrogen Alpha nebulae glow at a wavelength of about 656 nanometers. Any sensor, be it film or a CCD/CMOS chip, that has poor response in this area will be omitting a critical component of the image of the sky where H Alpha is present. My previous DSLR, a Nikon D100, had a weak H-alpha response, along with relatively high noise. The Canon EOS 20Da was dramatic improvement in both these area. That camera had a modified design especially for astrophotography, but still shoots perfectly good daylight images without any special filters. (Good info on H alpha here.) In early 2008 I had my 20Da modified to further improve its H Alpha response.
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