This agrees with the axiom that smaller scopes fair better with a UHC filter, and it takes a larger scope having more light gathering power to make full use of an OIII filter. You use what you have but it's a general guideline in contemplating a purchase. In going from a 10" to a 14.5" I kept the UHC. Jack Jones Saguaro Astronomy Club Lunar List Awards and Messier Marathon Coordinator Phoenix AZ spicastar@xxxxxxxxxxxxxxx When I observed this with my 15cm telescope in 1989, I found it better with a UHC filter than with the [OIII]. I noted that it "needs critically-averted vision to see much at all." Marling's 'true-visual' magnitude for this is 13.0, probably about right, but the large size makes it a classic low-surface-brightness test. \Brian -- This message is from the AZ-Observing mailing list. See this message's header if you want info about unsubscribing or the list's archive. This is a discussion list. Please send personal inquiries directly to the message author. In other words, do not use "reply" for personal messages. Thanks.