Astronomy stacker

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Autopano Pro as an Astronomy Stacker

Contents

If you want to use Autopano Pro for stacking astrophoto images, you need to know a few things to get good result :

  • When taking pictures of deep sky objects (galaxies, nebulae, etc.), you will need an equatorial mount with a clock drive. During the exposure, errors in the clock drive should be corrected using an auto-guider or by manually tracking a guide star.
  • Always make and process photos in RAW or 16 bit TIFF for better dynamic range.
  • Rotating the camera around its focus axis will reduce periodic error. For the best results, different frames of the same object should have different orientations.
  • Use a linear type blending when stacking images together.

When taking astrophotos, there are two cases to consider:

  • Photos of deep sky objects (nebulae, galaxies and so on)
  • Photos of the Sun, Moon and planets.

Deep sky Images

Deep sky images are difficult because they often require multiple exposures made with exposure times measured not it seconds, but in minutes. Individual images can even be taken at different times and locations. For a good final image, each of the individual images need to be carefully aligned and stacked together.

Open all RAW(16 bit TIFF) images.
Open all RAW images

Check all settings as shown (check lens distortion)
Detection Optimization

Set Planar projection
Panorama settings

Render this "panorama" into one stacked image, 16 bit TIFF.
Render Settings

Results
Result Image

Post Processing

We can correct the initial result using Photoshop (Image->Adjustments->Levels). Set the "black point" to get a dark sky background.

Result Image Levels

Here is the result with the black point adjusted.
Image:Deepsky_result2.jpg

Моve the middle point to the left to bring out more detail.
Image:Deepsky_result2_levels.jpg Image:Deepsky_result3_levels.jpg

Here is the result with the black point set and the middle point adjusted.
Image:Deepsky_result3.jpg

And here is the image after rotating and cropping.
Image:Deepsky_result4.jpg

Result Image corrected and cropped Levels
Image:Deepsky_result4_levels.jpg
If you use Noise Reduction Software (like Neat Image) before setting the black point and adjusting the levels, you will get a better, cleaner result. If you don't want to use noise reduction software, you can use internal level correction in AutoPano Pro before rendering the stacked image. You can reduce noise either by increasing the number of frames or increasing frame quality. For better frame quality, you need a good clear, dark sky away from city lights (like in the mountains for instance). You can also try to use special filters that reduce the light pollution spectrum. My source images are really very average. They were made in an area with strong city light pollution and without any special filter.

Final result

M31 The Andromeda Galaxy. Noise reduction in NeatImage 5
M31 The Andromeda Galaxy, Noise reduction in NeatImage 5

Sources for training

M31_2006_09_20.zip M31_2006_09_21.zip M31_2006_09_22.zip

Sun, Moon, planets

Stacking photos of Sun Moon and planets usually need for avoid atmospheric turbulence(that blurring image) and get more details and sharpness on surface.

Sun stacking

WARNING you need a special SUN filter to make a photos of the SUN. If you don' have it DON NOT ever turn your telescope or camera direct to the SUN. It will damage your eyes, you can become a BLIND and your equipment will be burned up.
Special Sun filters you can make from BAADER Astrosolar Safety Film.
BAADER Astrosolar Safety Film
Open all images, RAW is Really not necessary for SUN photos, because the SUN is very bright object. But if you want maximum quality you can make photos in RAW.
Open all images
Check all settings(uncheck lens distortion).
Detection

Optimization

Set Planar projection to correct perspective and geometric proportions.
Panorama settings
Render this "panorama" in one stacked image, 16 bit Tiff.
Render Settings
Output result.
Output result

Post processing

Rotate and crop image to make a right position and orientation of the Sun.
Rotate and crop
For better resolution on surface you can use special Wavelet Sharp filter in asto software like Registax. Left - not sharped, Rigt - sharped with Wavelet filter in Registax
Left - not sharped, Right - sharped with Wavelet filter in Registax
Example of Registax Wavelet post processing. This program is FREE, you can get it from http://registax.astronomy.net/
Example of Registax Wavelet post processing

Final result

Final result looks like that. Sun 2006/08/26.

Sun 2006/08/26

Moon stacking

Open all images. There is one tip - if images stacking incorrectly(because of low contrast), just cut it for square proportions.
Open Moon images
Check all settings: Detection, Optimization - the like in Sun stacking. Projection set to Planar.
Planar Projection

Post processing

Stacked image looks like that.
Stacked Moon
Crop it to square proportions, correct color (in Photoshop Image->Adjustments->AutoColor) and levels.
Stacked Moon, corrected color levels
Stacked Moon, corrected color
Increase surface resolution by Registax Wavelet filter. Left - not sharped, Right - wavelet sharped in Registax.
Left - not sharped, Right - wavelet sharped in Registax

Final result

Final Moon photo
All other planets processing is a similar, i don't have yet any source images for test this method on Jupiter or Saturn. For taking good pictures of far planets you'll need a really BIG telescope. If your telescope is small you can try to make a video of this planets and stack video frames in Registax.
That's all.
Sorry for grammar mistakes and hello from Russia :)
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