Quote:
Originally Posted by kinetic
Wow Greg that is deep isn't it! Beautiful capture.
I compared your shot to one I got a week or two back with
a 12" and DSI II and you have a whole 2nd set of spiral arms
showing!.... 
http://www.iceinspace.com.au/forum/s...ad.php?t=41268
Mine only shows the bright inner set, no sign at all of the outer ones!
Wow again.....As you say , the stars don't look too bloated without the
IR filter either.
Steve |
Here is a quote from Roland Christen of AstrPhysics where he explains why
a refractor can extract deep data more easily. He disagrees about the fluorite and he may well be right as Mike Sidonio's Centaurus A shows a non fluorite triplet will also do this.
"Lenses in general, and oil spaced triplets in particular, have very high light transmission efficiency. Refractor tubes can be ideally baffled to prevent stray light. If the figuring is good, then you can get very good focused energy into the image, which allows you to stretch it to extract ectremely faint detail. It has zero to do with the fluorite, but everything to do with the way the scope is built.
Tony Hallas discovered this himself when he was experimenting with various refractors at his deep sky site. He found that he could go far deeper with a refractor than he could with his 14.5" Cass before background light intruded into the image. Example is his latest M81/82 image, among others, which shows extensive faint extra-galactic dust around those galaxies. His scope is a 206mm F8 triplet apo, non-fluorite:
http://www.astrophoto.com/M81M82.htm
I also have a preliminary Rosette which he has not published yet, but which he will show at NEAF. It has faint detail in the core that I have not seen in any amateur photo. No fluorite was needed, just a well baffled oil spaced triplet refractor.
Rolando "
Quote:
Originally Posted by Ric
Lovely work Greg, you have brought out the best in that galaxy. The spiral arms are a real treat.
Cheers
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