Re: Planet X: FITS files (FYI Tholen)
Michael L Cunningham wrote in message <3DEA81A3.firstname.lastname@example.org>
> email@example.com wrote:
> > Shouldn´t these pixel defects be on all frames?
> > I searched for pixel defect and found this.
> > "At these prices, all CCDs will have lots of defective pixels - out of 3
> > million there will be hundreds of them that are substandard. The camera
> > maps out the bad ones and fills in the gaps with data from neighbouring
> > pixels. To get a perfect 3Mp sensor will cost you a small fortune. It is
> > not acceptable if you see a bad pixel - it means that during
> > manufacturing that this bad pixel was not properly mapped out or the
> > defect surfaced after manufacture (which is possible). Take it back
> > and demand a replacement."
> Big difference between a Powershot G! commercial digital camera and a
> CCD astronomical camera. I own a Powershot and would never dream of
> using it to image anything more than the moon of the bright planets thru
> my scope.
> Astronomical CCD's are imaging objects that are millions of times
> fainter than that of smiling faces in sunlight or even in your living
> room under the light of a lamp. Take an image in a darken room with your
> standard commercial CCD camera and notice how grainy it looks. This is
> called noise and comes from heat sources and the camera electronics.
> Commercial cameras rely on extremely bright sources when taking images
> where astronomical cameras are cooled to remove as much heat as
> possible. We also take dark, bias, and flat frames to remove as much
> noise from other sources while processing our images.
> The Zeta faithful REALLY need to read up on the technology of imaging
> and image processing as it relates to astronomical imaging! I have yet
> to hear that Dell, Nancy, or Havas have read up on any documented
> imaging processes printed by a reputable authority in the field! Duh!
> Havas is still grasping for straws and fails to grasp the simplest terms
> as offered to him when it comes to image processing. Lord help him if
> and when he ever attempts astrometry on his "object".
We were talking about pixel defects Michael, not the quality of CCD.
Does professional astronomical CCD´s process pixel defects as stated
in my previous article?