Thanks for the reply gb,
I have already done a lot of research on the subject.
Please visit the following thread to see where I am up to.
http://www.ufonv.com/viewtopic.php?f=19&t=916
There you can see a comprehensive comparison of ISS with various configs.
At the moment I am left with the couple of questions mentioned previously.
I would like some expert help with suggestions please based on past experience with telescopes and astrophotography.
If you know someone that could be of help, it would be great if you could please point them here.
Thanks again
Telis