StarStructure 24" f/3.3 | ServoCAT/Argo Navis
Astro-Physics 175EDF | AP1100GTO | ATS Portable Pier
Psalm 19.1 - A Psalm of David. "The heavens declare the glory of God, and the sky above proclaims his handiwork".
David-------David Lukehurst UP 20" f/4, Orion Optics ODK12, CFF 180, Borg 125SD, Wiliam Optics FLT98, Borg 71FL, TS 50EDLunt LS60THa + LS60FHa
~Suneet NexStar 11 (XLT) 279.4mm f/10.0
Homemade 14.5" f4.3 Truss Dobsonian
"I'd like to remind you at four in the morning my world is very still, The air is fresh under diamond skies, makes me glad to be alive." Randy Bachmann "Blue Collar"
“A mind is like a parachute. It doesn't work if it is not open.” ― Frank Zappa
Rob 18" f/4.3 Starmaster 8" Meade LX200 Classic Celestron 15x70 Skymaster Binoculars
22" f/4 Sayre Monocular, Tom Osypowski Equatorial Platform (since 1995), Assorted small telescopes 76-152mm; 25mm ES100°, 20mm ES100°, 13mm Ethos, 9mm ES120° (serial #18), 9mm ES100°, 8mm Delos, 6mm Ethos, 4.7mm Ethos, 3.7mm Ethos SX, 2.5mm Nagler Type 6, 2" 2X Powermate, 2" 1.5X Proxima Barlow, 2" GSO Coma Corrector, 18mm BCO, 10mm BCO, 6mm BCO and other 1.25" eyepieces. Zhumell 8x42 Nova Phase-coated ED Binoculars, Burgess 25x100 Binoculars
Quote:A barrel extender would protrude into the light path, causing diffraction.A simple light shield does the job without causing any extra diffraction and also serving the additional benefit of reduced dewing issues.
400mm f/4.46 self made Dobsonian on Tom Osypowski equatorial platform Skywatcher 130mm f/5 BlackLine (finder, widefield scope and solar continuum scope) Sumerian 250mm f/4.8 Alkaid (as travelscope without platform and on Tom O. platform above).
Quote:The thing that makes me lust for a Paracorr II is the proper correction for the 31 Nagler and 21 Ethos, which combined are 50% of my eyepiece collection. The Paracorr I does not perfectly correct either of these.
Quote:Rob et al,
The new Type 2 is better at EVERY focal ratio than the Type 1, not just fast focal ratios. As I understood Al Nagler, it really isn't optimized for a particular focal ratio.
I would definitely recommend the Type 2 over the Type 1 at F/3.7. Vic Menard could easily see the improvement in his F/4 scope at WSP. It not only improves edge correction, but also field curvature, so the outer part of the field is improved.
Lockwood Custom Optics
From: Peter Natscher
To: Mike Lockwood
Sent: Tue, April 20, 2010 9:52:10 AM
Subject: Paracorr Type 1 or Type 2 For F/3.7?
Paracorr Type 1 or Type 2 For F/3.7?
The Paracorr Type 2 was just officially announced. My 24” mirror that you made for me has a focal ratio of f/3.7 that is in between the two Paracorr optimizations of f/3 and f/4.5. Would there be any advantage in using the new Type 2 Paracorr over the Type 1 that I already use? I think a lot of Dob owners will want to know where their mirrors stand with regards to choosing either Paracorr.
woody a parsec farther out...
12.5" f/4.8 custom truss dob, EQ platform
Quote:However, I should note that the Skies Unlimited web site makes reference to somewhat different information to consider in choosing between the Type 2 and Type 1: "The original Paracorr has been optimized for f/4.5, whereas the new Paracorr Type 2 is optimized for f/3. This begs the obvious question of where to draw the line in choosing one over the other.
Darren in Bakersfield
Quote: As has been said, it really depends on your eyepieces. I'll upgrade before next summer. My 31n and 21e demand it.