Quote:
Originally Posted by freespace
I have a 4" scope, and I observe until moderate light pollution 90% of the time - would love to know if it helps.
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Steve,
I have tried the Orion Ultrablock both in my ED80 and my 8" f/6 Newt (under mag 5.5 skies) - while it improves contrast and detail dramatically in both scopes the view in the ED80 is so dim that on nebulas fainter than say eta Car or M42 it might not leave much to look at. Some filter manufacturers recommend not using UHC or anything like it on scopes smaller than 8".
I have also tried Astronomik CLS on both scopes, and for the 80mm I actually prefer it over the Ultrablock, also because it does not add the blueish hue to the colour of the stars. Astronomik also have the UHC-E (with a slighty broader passband than UHC) which they recommend for smaller scopes, but I have never tried it:
http://www.astronomik.com/english/eng_uhc-e.html
Tom