Just out of curiosity, if aperture during the daytime does no good, then why are the professional solar scopes large aperture? Not as large as the night time scopes, but still bigger than anything I have owned. From: Chuck Hards <chuck.hards@gmail.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Tuesday, March 6, 2012 12:33 PM Subject: Re: [Utah-astronomy] solar filter On Tue, Mar 6, 2012 at 12:22 PM, daniel turner <outwest112@yahoo.com> wrote:
The central obstruction boogy man is a long held myth.
Not strictly true, Daniel, but in the case of solar observing it's usually not an issue so I'm going to agree with the gist of your post and just pick a minor nit. It can become so large as to be noticeable with large exit pupil diameters (very low powers), so much so that you end up with a shadow in the center of the field. But again, this isn't usually a problem with solar observing. Diffraction artifacts such as spikes and rings, being low-contrast, are typically noticed only on night-time bright and point-source objects. The central obstruction's destructive influence isn't noticed otherwise, unless it's huge. Daytime seeing conditions rarely allow diffraction-limited viewing with large apertures, so 4-6" is usually sufficient for even high-powered views. I have found 2" to be a good working minium. Just enough resolution to see smallish details, and bright enough for a pleasing view if your filter extinction isn't too great, or it's a weird color like green or orange or blue. Full-aperture filtration is desireable, for those occasssions when the seeing conditions will support it. Having the option of a hi-res view is nice. _______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options".