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[ATM] BAFFLES
RE: Baffles
Thanks, Andy for the input regards black painted surfaces. I have played around with different surfaces myslf and have found black cloth to work well but difficult to use on the inside of the tube. Many plack paints are anything but dark at low angles. I have conducted experiments on two "identical" 6in F/8 scopes and have found the larger tube nested with smaller to be significantly darker as judged by camera placed at the primary position and moon hidden behind secondary. Many "black" paints show plenty of reflections at low angles. Of course measurements at the focus with uniform source would be better measure but I did not get around to this. I could NOT appreciate the differnce visually, but I am limted to the bright skies outside of Philadelphia!
John
Andy Saulietis writes:
For my own scopes, I use Krylon 1602 Ultra Flat Black spray paint.
Works great if
applied just thick enough to cover the surface. Additional coats
actually increase the
reflectivity.
The blackest surfaces I've seen were acetylene soot (fragile &
messy), and a proprietary
anodizing process called Martin Black (horrendously expensive and
only works on some
aluminum alloys). Both of these reflect <0.5%. Black velvet or black
flocking is in the 1%
range but can be difficult to apply.
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