Amature webcam capures
The PST does not show maximum contrast of Hα features across the entire solar disk at one time features visible on one side of the disk will disappear when the scope is turned to show details on the other side.By shooting a series of exposures that record features at different tunings, you can combine them to create a portrait showing detail across the entire Sun.I had to shoot my photos using either eyepiece projection or a focal imaging (aiming a camera's lens into an eyepiece).My first afocal images were taken with a borrowed Nikon Coolpix 990 and a Tele Vue 19-millimeter Plössl eyepiece.In addition to the uneven illumination, the PST has limited back focus.While not a problem for visual use, the focal plane is very close to the top of the 1¼-inch eyepiece holder, and there is not enough back focus for an SLR camera.In this magazine's February 2005 issue, page 96, I reviewed Coronado's Personal Solar Telescope (PST) a groundbreaking instrument that brings hydrogen-alpha observing to amateur astronomers at an affordable price.
I use from 3 to 20 frames, but I tend to capture at least three images at each setting of the tuning ring in an effort to get at least one during a moment of good seeing.
The three images shown above have been contrast stretched to better display the differences between them.
To overcome the PST's uneven illumination, I capture several exposures, turning the scope's tuning ring slightly between each one.
I found that a small video monitor attached to the camera made focusing easier, because the larger image made it easier to see when the best focus point was established.
When a monitor isn't available, I use the small screen on the back of the camera, placing a dark cloth over my head to shield the screen from bright sunlight and help me see low-contrast features.
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Thus the entire solar disk isn't evenly illuminated, and prominences are visible on one side of the Sun while not on the other until the PST's tuning ring is turned to display that area properly.