On Tue, 21 Nov 2006 23:23:22 GMT, "Terry B"
wrote:

I have recently borrowed a ST7 with an KA0401E chip with antiblooming. My
camera is a Genesis CCD with the non antiblooming version of the same chip
that I build many years ago. I have been amazed at the difference in the
sensitivity. Some of this may be related to using different programs to take
the pics. Is it due to the antiblooming or just different design of camera?

With the KAF chips, the antiblooming system works by draining away
excess electrons. By its nature, a certain percentage of all electrons
are lost. In addition, the antiblooming requires a gate structure on top
of each pixel that reduces the collection area (the newer chips with
microlenses largely compensate for this loss). The QE of the NABG sensor
is a good 50% higher than the ABG. In addition, the ABG sensor isn't
linear, so it isn't a very good choice for some scientific work,
especially photometry.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com