Quote:
Originally Posted by glend
I have a small stack of subs of the Horsehead taken early this morning, subs are 4 x 270", stacked with darks and offset frames. These were take through my SKywatcher MN190 with the Canon 450D (full spectrum modified - but not the cooled camera). What concerns me about this image is the dark donut artifacts at various places on the image - which is really annoying. I had cleaned the front anti-alysing filter prior to the shoot, as I had seen something like this from this camera before. The cooled camera doesn't show these. I suspect there is something either on the rear of the anti-alysing filter or on the surface of the sensor itself. Is there any way of processing these out, would Flats do that? I know I will have to disassemble the camera to clean the sensor and back of the front filter.
Here is the Astrobin full size link (in jpg of course as that's all Astrobin supports in the Gallery):
http://www.astrobin.com/full/205820/0/
Small version is attached here. |
Glen,
nice shot
There are only a few spots
Open a copy of the image in Photoshop
Duplicate the base layer
Gaussian Blur ~ 25 pixels
Blend mode on Lighten
Create a layer mask
select the mask
invert the mask or fill it with black
Get a blurry paint brush ~50 pixels 100% opacity. Dab white spots over each of the marks until they disappear
takes about 5 mins
cheers
Joe