Image ComparisonBelow is a comparison of my work for the Horsehead and Flame Nebula dating back to 2006. This represents the difference that experience with equipment and software makes when it comes to astrophotography. Click on each thumbnail for the full-size view.
|2006 Image||2010 Image||2011 Image|
.For comparison, here are the details for each of the three photos:
|2006 Image||2010 Image||2011 Image|
|Telescope Mount||Meade LX200||Celestron CGEM||Celestron CGEM|
|Telescope Optical Tube||Orion ED80||Orion ED80||Orion ED80|
|Imaging Camera||Canon Digital Rebel 300D||Canon XSi 450D||Canon XSi 450D|
|Autoguider||None||Orion Awesome Autoguider Package||Orion Awesome Autoguider Package|
|Final Image Editing Software||Adobe Photoshop 7.0||Adobe Photoshop CS3||Adobe Photoshop CS3|
|Light Frames Stacked||10 x 5 min at ISO400||8 x 6 min at ISO1600||5 x 10min at ISO1600, 10 x 5min at ISO800, and 5 x 8min lights at ISO800|
|Dark Frames Subtracted||Yes||Yes||Yes|
Number of Frames and Exposure TimesMy 2011 photo is much improved over the other two. An obvious difference is the increased number of light frames and exposure times. The frames for my 2011 image were taken over the course of two nights and combined in DeepSkyStacker (free download). In astrophotography, it is very important that the final composite image be composed of as many frames as possible. The more frames, the better the signal-to-noise ratio (more signal, less noise). My 2006 image and 2010 image both suffer from a lot of noise. They would have benefited from more frames. My 2011 image had some noise too, but much less than the other two images. I was able to remove most of it with software as I mention later. The final result of stacking yields a richer, more natural-looking photo.
AutoguidingThe ability to take long exposures can be attributed to the use of an autoguider. I use the Orion Awesome Autoguider Package as shown in my review here. I did not have this capability in 2006 with my LX200 so my polar alignment had to be extremeley accurate and my exposure times were very limited. I could do 5-minute exposures, but had to sort through them for the few good ones that were suitable for stacking. With the Orion autoguider, I get to keep almost every exposure I take. Plus, I can capture much longer exposures which is important for acquiring fainter detail such as nebulosity. I took 10-minute exposures for my 2011 image with no problems. I have taken up to 20-minute exposures while using this autoguider with perfect frames each time. I continue to endorse the Orion autoguider since it is a low cost system and has worked really well for me.
Noise RemovalEven with stacking numerous frames, there was still some amount of noise in my image. To help on this, I used a free program called Noiseware Community Edition from a company called Imagenomic. I found it to be relatively easy to use and it did a pretty good job of removing the noise in my image. Below is a video from my good friend Jeff Turner from DaltonSkyGazer. He provides a nice overview of using this tool. [youtube]http://www.youtube.com/watch?v=i_HUlhNYr3s&feature=player_detailpage[/youtube]
Processing in PhotoshopSome of the real magic occured in the final phase of image processing. I used some of the techniques that Adam Block teaches in his DVD tutorial for processing astro-images. Some of the filtering methods explained in the video really brought out the finer details that were hidden in the original photo. For instance, the Flame Nebula was soft and dim before using Adam's techniques. The final photo shows nebulosity that is sharp and full of fine details. The Flame really blossoms out with a 3-dimensional effect. The entire image is very rich and really comes to life! Adam's DVD tutorial available here.
DSLR Astrophotography MethodI am continually refining my methods for acquiring and processing images. For my recent Horsehead and Flame Nebula photo, I followed my latest tutorial for DSLR astrophotography very closely. This tutorial covers the following:
- Astrophotography Equipment
- Telescope Setup
- Attaching the DSLR to the Telescope
- DSLR Computer Connection
- EOS Utility Instructions (automatic shutter control)
- Object Centering and Focusing
- Autoguider Setup
- Collecting Light Frames and Dark Frames
- Processing in DeepSkyStacker, ImagesPlus, and Photoshop
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