PST Basic Disk Imaging (14 images) Imaging the solar disk with a PST Cak or Ha and a Meade Electronic Eyepiece
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Notes
The basic imaging technique show here is suitable for beginners to become comfortable making low-resolution documentation style PST Ha and CaK images without purchasing expensive advanced gear.
PST Ha imaging is effective within 18° of the meridian transit - about one and one-half hours around solar transit. PST CaK imaging will return detail up to 25 to 35 degrees off the meridian. However, the best detail, particularly in the PST Ha, is seen in the 15 minutes on either side of transit. That one-half hour window is the best time for solar Ha and CaK visual observing and for imaging.
Imaging as the Sun transits also simplifies other orientation tasks. At transit, Sol can be easily aligned in the video chip to drift east and west across the screen. North and south on the local horizon easily can be detected by pressing the back of the scope up or down or side-to-side with a finger.
Some initial interpolation of default brightness, contrast, hue and saturation settings will need to be done. Once useable settings are found, write them down for future reference. It is possible to have a functioning setup, but you will be unable to focus because the brightness and contrast settings on your S-video capture device initially is causing the disk to white-out. For initial testing, set the preview image to dim and high contrast. The interface for an S-video capture device varies between manufacturer. A moleskin component setup field notebook is useful to make sketches and notes on your successful component layouts and software settings. For the Belkin S-video capture device shown here, the settings used were: brightness - 10, contrast - 29, hue - 13, and saturation - 4.
The Meade electronic eyepiece (MEE) is not suitable for prominence imaging. First, the MEE, in conjunction with the Belkin S-video capture adapter shown here, has an automatic gain control that cannot be disabled. The camera always adjusts the gain to image the brighter disk. Second, the MEE captures avi. Avi format does not have enough dynamic range to capture the bright disk and prominences.
Once you are confident using this basic setup and Registax operation, upgrades can include: 1) substituting a tracking mount for the fixed mount and 2) substituting a TeleVue 2x Powermate and/or a high megapixel digital SLR camera for the MEE.
If the Sun is imaged as it transits, other observing note-taking tasks are simplified. With a time and date note, resources such as the U.S. Naval Observatory online astronomy applications and Les Cowley's Tilting Sun desktop application can be used to estimate the rotation of the Sun on its north-south axis and the approximate latitude and longitude of features - even if you are using a non-tracking, fixed alt-az mount.
