Foundations of Imaging Observing Program Coordinator:
Appendix 1: Bright Solar System Objects
(Software references as of May, 2020)
The following is presented to develop key concepts of imaging and astrophotography, including terminology, equipment used, software used, fundamental concepts of image processing, and common vocabulary. You are encouraged to seek out more detailed works that can be found in print and on the internet. Suggestions and tips follow the text. Free software is indicated as (free).
Photographically interesting bright solar system objects include the Sun, Moon, Jupiter, Saturn, Venus, and Mars. The other solar system objects are either too small, dim, or produce featureless results. While you may capture and stack multiple images using a DSLR, the bright objects are best captured with video capture software utilizing the highest shutter speed possible while retaining detail in the exposure. Video allows thousands of frames to be captured in a relatively short time while high shutter speeds will help minimize the effects of atmospheric turbulence (poor seeing). The resulting frames are then stacked with software to produce the best results. You should try to avoid video modes that are lossy or overly compress the final movie. The resulting files may be huge. The larger the file, the longer it will take to process later. If available, use the Region of Interest (ROI) feature of your camera to create smaller files and allow higher frame rates.
The video files can be processed with AutoStakkert! (free), RegiStax (free), or similar software. A Google search should produce tutorials for using the various packages. Processing will produce the best single image of the object from the video by combining the best parts of the best frames. If the software is unable to read your video file it probably means that there is a codec (translator) missing on your computer. It may be easier to use a product like VirtualDub (VDub free) or Planetary Imaging PreProcessor (PIPP free) to translate the video to the acceptable format than to find the correct codec on the Internet.
The resulting image should be post processed with other software to improve the final results. RegiStax offers wavelet sharpening. Astra Image offers both wavelet sharpening and deconvolution. The image may also be processed in PhotoShop, GIMP (free), PixInsight, or other program. WinJUPOS (free) has the ability to correct for planetary rotation during long exposures. Multiple programs may be used to process your images.
Suggestions and Hints:
- Never point your camera/scope at the Sun without suitable filtration in place. The filter should be placed so that the light is filtered before it enters the telescope or lens. White light solar filters can be purchased from a variety of vendors.
- The software to capture, stack, process, and post process is constantly improving. New versions are frequently released. The software mentioned here, reflects what was available in May, 2020.
- Online sites like CloudyNights, The SkySearchers, etc. have active forums that will announce the latest, greatest software. Check these sites if you are interested in using these offerings.
- Most software will have a groups.io or other forum site. You are encouraged to seek out these sites, to join, and to post your questions there.
- Many online sites have provisions for you to upload your work for critique. Self criticism is always difficult, particularly for beginners. Sometimes you will not notice a problem with your work, while others who are more advanced will. An example might be having out of round stars in the corners of your work. Take the comments with a “grain of salt,” but do be open for suggestions to improve your work.
- Seek out other astrophotographers in your area for sharing.
- Consider attending star parties and workshops with astrophotography sessions.
- Equatorial and Alt/Az mounts both work well for capturing the brighter solar system objects. While not required, a tracking, GoTo mount is suggested to make finding and centering easier, particularly at higher magnifications.
- For Prime Focus Astrophotography mount your camera to your scope using a T2 adapter for your particular camera brand and nosepiece (1.25” or 2” depending on your scope). (Google prime focus astrophotography for more information.)
- Use third party software like Backyard EOS, Backyard Nikon, Sequence Generator Pro (SGP), Nighttime Imaging ‘N Astronomy (N.I.N.A) (free), etc. to control a DSLR.
- Use third party software like SharpCap (free version), FireCapture (free), etc. to control planetary/solar system/low light video cameras.
- In planetary imaging, “video” refers to uncompressed high frame rate .SER or .AVI format files and should not be confused with compressed .mpeg or .mp4 files generated by a video camera or DSLR.
- Jupiter is best when it includes the Great Red Spot, moons, or moon shadows. Go to Sky & Telescope’s interactive tools and check for Red Spot and moon transit times, and plan your recording sessions accordingly.
- Filters of various colors can enhance detail. A filter lightens its own color and darkens the opposite. To darken Jupiter’s Great Red Spot, you’d use a blue filter. It will turn the rest of the picture blue too! An ultraviolet filter will show cloud formations on Venus.
- Virtual Moon Atlas is very helpful in locating features on the Moon. It also suggests when it is the best time to photograph various features based on phase.
- The magnification of the object depends on focal length and the camera’s pixel and sensor size. For a given camera, the longer the scope/lens focal length, the bigger the object in the image. Likewise, the more densely packed the pixels, the bigger the object will be in the image. Consider using a Barlow to increase your focal length to achieve at least a focal ratio of f/11, but do not exceed f/22. Faster exposures time freeze motion blur caused by seeing and often result in more image detail than excessive focal length. JohnDudak’s online FOV calculator is helpful in determining what to expect from your setup.
- Use a histogram to ensure the highlights are not clipping. Clipping is evidenced by a spike in the far-right side of the histogram.
- Better images should result when the object is high in the sky vs. low and near the horizon. Use an Atmospheric Dispersion Corrector (ADC) when imaging planets below 45º altitude. Infrared filters help mitigate seeing.
- It may be difficult to record both detail in the planet and the planet’s moons. You may need to combine two images, one for correct planetary detail and a second for the moons.
- Single images of the Moon or Sun (with proper filtration) can be taken with the camera on a tripod and a telescope/telephoto lens.
- You may need to put your drive in lunar or other drive mode to track for long sessions.
- Focusing is critical. It is easier to focus using a computer screen than looking through the camera’s viewfinder or at the camera’s LCD display. A good manual focusing procedure is to use a Bahtinov mask (or other suitable mask) to focus on a nearby star and then slew to the object.
- Hydrogen-alpha telescopes like the Coronado PST are designed for visual work. You may need to use a Barlow in the path to achieve focus. It is also easier to focus on the Sun in monochrome than in color. You may also need to do a mosaic to get an image of the entire Sun. Many solar imagers combine multiple black & white images to get the final result, adding color later in Photoshop. Surface detail and prominences are difficult to capture with the same exposure, so consider multiple exposures a few f/stops apart and then combine.
- Turning up the saturation of lunar images will produce areas with different colors.
- Bright solar system objects do not require particularly dark skies compared to DSOs. You can capture images from light polluted urban environments.
- The coordinates (RA/Dec) for dwarf planets, comets, and asteroids can be estimated by the same means presented in the Astronomical League’s Solar System Program under Asteroids. For better results consider plate solving and using software like MuniWin (free), AstroImageJ (free), or Astrometrica, etc. to precisely measure their position.
- Many great ideas and helpful hints for wide field photography can be found at The World at Night (TWAN) website.
- Depending on your equipment, some tasks (solar and lunar disks) may require assembling individual frames into a mosaic. Microsoft ICE is one of many free programs that can do mosaics. Nearly all photo editors such as PhotoShop and Affinity Photo perform nearly flawless mosaics using their panorama function.
- Predicting when lunar occultations and grazes will occur at you location is easily done with the International Occultation Timing Association’s (IOTA) program called Occult4 (free). The IOTA has a manual for timing occultations that describes Occult4.
- Sites like YouTube will have video tutorials for software that will both demonstrate its use and answer many of your questions. Be sure you are looking at current videos.
- You are encouraged to submit your best images for possible inclusion in the Astronomical League’s Reflector magazine – firstname.lastname@example.org.
- Most importantly, have fun!
Fundamentals of Imaging Observing Program Coordinator: