Sun in H-Alpha
The following images of the Sun were taken with my Coronado Personal Solar Telescope (PST) and also my SolarMax60 filter mounted on my undriven Zeiss Telementor refractor. The images were acquired using my Starlight Xpress SXV-H9 CCD camera. See also my Solar webcam images.
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Coronado SolarMax60 filter and Zeiss Telementor |
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The image processing steps I used for the CCD solar images are detailed at the bottom of this page.
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17th Feb 2008(SolarMax60 on Telementor) |
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8th April 2007(SolarMax60 on Telementor) |
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24th Sept 2006(SolarMax60 on Telementor) |
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10th Sept 2006(SolarMax60 on Telementor) |
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8th Sept 2006(SolarMax60 on Telementor) |
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29th June 2006(PST) |
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| 23rd June 2006 (PST) |
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| 11th June 2006 (PST) |
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10th June 2006 (PST) |
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7th June 2006 (PST) |
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When using the PST, in order to for the solar image to fully cover the CCD chip, I used a lens elements from a cheap 2x barlow lens screwed directly into the camera nosepiece. Using AstroArt 3.0 the shortest exposures available fully saturated the chip. A neutral density filter allowed me to dim the image sufficiently to get suitable exposure settings. Solar images are taken with an exposure time that is sufficient to cover as much of the 16bit dynamic range of the CCD as possible. With my setup of a 2x barlow lens and neutral density filter, an exposure of between 300ms and 500ms works well depending on the altitude of the sun in the sky. The level histogram is used to make sure that as much of the dynamic range is used as possible. Once suitable images are acquired they are converted from FIT images to 16bit TIFF files for use in Adobe Photoshop CS.
Once a suitable image has been acquired, a copy is made for use in creating a pseudo-flat field image. The flat field image is loaded into Photoshop and the clone tool used to remove any of the details in the image (i.e. flares, prominences and filaments etc.). A gaussian blur is applied to blur out the details, and the brightness is reduced by about 50 percent. This is then saved as the flat field image.
The main image is loaded into Photoshop. An unsharp mask is applied to help bring out any details. The levels are adjusted to cover as much of the dynamic range as possible. A new layer is created and the mode changed to "difference" and opacity is set to 50%. The flat field image is the loaded into this new layer and helps correct the solar edge dimming or hotspots in the image. The opacity and brightness of the flat can be adjusted to give a pleasing result.
Once you are happy select "Image/Mode/RGB Color" to allow you play with colours. Now select "Image/Adjustments/Curves". For the RED channel move the curve up, for the GREEN channel move the curve down, for the BLUE channel move the curve further down. You can play with these until you are happy with the colour then flatten the image and save it in whatever format you want.