Hi yall,
I've posted a shot of the two large sunspots that are currently on the sun.
It's at: http://www.astropix.com/HTML/SHOWCASE/SUNSPOTS.HTM
Although it was taken with a Nikon D1h digital camera, the image processing
may be of interest to the few film photographers left alive on this list.
A series of approximately 300 images were taken manually one after another
with the camera in anti-mirror shock mode and triggered with the self-timer
to reduce vibrations.
The raw images were then imported into Photoshop 7 with the Adobe Camera
Raw plug-in and were exposure adjusted, contrast increased and sharpened in
the ACR module. Because the images were low noise from having been shot at
ISO 200, noise reduction in the ACR module was set to zero.
All of the images were then opened in Photoshop and enlarged to 20! 0 percent
and examined for sharpness and the best image was selected.
The image was further adjusted in Photoshop for tonality, and sharpened
with an unsharp mask of 100 percent, 0.5 pixels and 0 levels. Another
unsharp mask of 100 percent, 2 pixels and 2 levels was applied. False color
was added with a layer in the darken blending mode.
Shooting 300 images was a method of hoping to luck out and get one with a
moment of especially good seeing. This technique goes back many decades and
has recently been advanced greatly with web cams for planetary photography
where videos are shot at a high frame rate and specially designed software
selects the sharpest frames and stacks them together to create a low-noise
image.
In the case of a web cam, the images are relatively low resolution in terms
of the total number of pixels, but the resolution of the seeing is matched
to the image size at the focal plane producing excellent res! ults. In this
case a larger file size of approximately 3.5 megabytes was produced by the
Nikon digital camera.
Jerry
Photoshop for Astrophotographers - http://www.astropix.com/PFA/PFA.HTM
_______________________________________________
Astro-Photo mailing list
Astro-Photo@seds.org
http://seds.org/mailman/listinfo/astro-photo
Dominic Cantin
http://spacew.com/gallery/DominicCantin
_______________________________________________ Astro-Photo mailing list Astro-Photo@seds.org http://seds.org/mailman/listinfo/astro-photo