Re: [APML] Sunspot Picture

[<apml@andreasroerig.de>]

Hi Jerry,

do be honest, I don't have much experience about sun photography but
your images are simply fascinating. Very good detail!
Thanks for sharing your detailed description of image aquisition and
processing.

Best regards
Andreas


:=============================
: Andreas Roerig
: http://www.andreasroerig.de

Jerry Lodriguss <jerry@astropix.com> schrieb am 31.10.2003, 10:44:14:
> 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 200 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 results. In this 
> case a larger file size of approximately 3.5 megabytes was produced by the 
> Nikon digital camera.
> 
> Jerry
>
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