Quote:
Originally Posted by gregbradley
Yes same. Best views were always with a refractor. Stars can be pinpoints and better contrast and cuts through the seeing better.
Eden, that's a great comparison graph you've got there. Thanks for that.
Where did you get that from?
Gee the 11002 is very insensitive to Ha. Also I thought the QE of the 8300 was more like peak at 60%. That's what FLI rates theirs at.
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You're welcome, Greg. I thought that you might find it to be of some interest.
The QE graph attached was done by Philippe Bernhard (
http://astroccd.eu) however I sourced it from
http://blog.astrofotky.cz/, which has some excellent CCD related articles.
Having looked at many such graphs, both independent and vendor-supplied, I have found that QE sensitivity tests done by independent 3rd parties tend to give a much more realistic "real world conditions" assessment of CCD performance. A lot of this has to do with the fact that many camera vendors simply provide the default QE graph supplied by the CCD sensor manufacturer and if you read the fine-print which accompanies these sensor manufacturer QE graphs you will find that the test conditions under which they were generated not only vary between sensors, but also deviate wildly from the typical astrophotographical conditions in which these sensors are often used. Sensor manufacturer QE graphs also fail to account for other factors such as the coatings found on refractor lenses and camera windows.
This is where the CCD sensor comparisons provided by Point Grey are particularly reliable -- they use industry standard test conditions which are consistent right across all test articles and give you an accurate assessment of the performance of an actual camera, not just the sensor.
If star size is of concern in a photographic setting, I would definitely suggest at least investigating UV suppression. I have observed a noticeable decrease in star bloat after switching from a Baader filter with relatively low UV suppression to an Astronomik filter with high UV suppression. This is with an OSC camera with relatively poor UV blocking at the sensor window. Obviously in a narrowband setting the luminance channel would be the culprit.