· Get a Cloudy Nights T-Shirt · Submit a Review / Article Click here if you are having trouble logging into the forums Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User You are not logged in. [Login] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Equipment Discussions >> Binoviewers Previous   Index   Next   Threaded   Pages: 1 teskridg Pooh-Bah Reged: 01/15/08 Loc: PA Central obstruction shadow.       #4269951 - 12/24/10 04:50 PM Edit   Reply   Quote Quick Reply   Just got my A-P visual back for my CPC-1100 and installed my Earthwin binoviewers and power x switch and noticed the central obstruction shadow when daylight viewing some trees with a pair of Televue 32mm Plossls. Is this due to the daylight viewing and the smaller pupil and will it be visible at night? Tim Post Extras:       Arizona-Ken Pooh-Bah Reged: 08/31/08 Loc: Scottsdale, Arizona Re: Central obstruction shadow. [Re: teskridg]       #4270139 - 12/24/10 06:21 PM Edit   Reply   Quote Quick Reply   Be patient my friend! I have the CPC1100 and EarthWin combination like you and the views are dynamic at night. Be patient and have a Merry Christmas! Arizona Ken Post Extras:       hbanich scholastic sledgehammer Reged: 06/17/05 Loc: Portland, Oregon Re: Central obstruction shadow. [Re: teskridg]       #4272986 - 12/26/10 05:01 PM Edit   Reply   Quote Quick Reply   Hi Tim, I think you're right - your smaller daytime pupil diameter is the reason you're seeing the central obsruction at low power. With 32mm Plossls I doubt you'll notice this at night. Post Extras:       teskridg Pooh-Bah Reged: 01/15/08 Loc: PA Re: Central obstruction shadow. [Re: hbanich]       #4274409 - 12/27/10 12:55 PM Edit   Reply   Quote Quick Reply   Thanks all for the replies. I had 24mm Panoptics which I sold because of severe vignetting in the reduced mode of the p x s and got the 32mm Televue Plossls; for some reason there's less vignetting with these despite what I gather is the same field stop diameter. In addition, I like the appox. 100x magnification with these (considering the longer effective focal length of the 11" SCT rendered by adding the p x s diagonal and binoviewer) better than that provided by the 24mm Panoptics. Anyone else with an opinion on this? In the barlowed mode of the power x switch, the 24's would yield about 260x, which for my seeing conditions is usually excessive. Tim Post Extras:       Fred1 Carpal Tunnel Reged: 09/19/07 Loc: Somewhere in the Orion Spur Re: Central obstruction shadow. [Re: teskridg]       #4274460 - 12/27/10 01:33 PM Edit   Reply   Quote Quick Reply   Tim, the TV 32mm Plossl and the 24mm Pan provide the same TFOV, however the 32mm is probably giving about 50x less and a brighter image, so I imagine the vignetting is less noticeable because of the lower power, narrower "apparent" field and additional brightness. I'm sure others can provide a more technical explanation regarding how the eye/brain overcomes the vignetting. Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 0 registered and 3 anonymous users are browsing this forum. 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