The more I look for faint details in DSO's, the more I turn to DSF
Just worked out an observation in September for planetary nebula NGC7027 in Cygnus, a.k.a. the "Green Rectangle" or the "Magic Carpet Nebula".
A notable feature in this nebula in my 12" SCT is a bright knot on the NW edge of the NW part. Pumping up the magnification revealed further detail. Detail I beforehand would not have expected to pick up in a 12" scope. Below is my observation using different magnifications, filtered and unfiltered. One could perhaps conclude that filters wash out detail in this nebula using a scope of this aperture.
I look forward to hearing whether or not you observed similar detail in comparable or larger scopes!
12" SCT, rated the PN 8/10:
179x / 27': A NW-SE elongated nebula, without using AV clearly brighter on the NW side in a small, round knot with a fainter, elongated nebulous part to its SE. The color is clearly bright turqoise, towards green. Larger when using AV and even in brightness, the rectangular shape (NW-SE) is clear.
OIII: Without use of AV it is clear that the bright knot is on the west side of the NW part. Using AV brighter in the NW part where the nebula was even in brightness without use of this filter. UHC: Same effect as OIII but not as strong.
277x / 18': Using this magnification, both with and without AV, the NW and SE part of the knot on the NW side appear, very faintly, to be just separated from one another by a small dark part running NE to SW.
OIII: Almost even in brightness, just a little brighter in the NW part. UHC: As with OIII.
436x / 11': Using this magnification the knot on the NW side of the NW part is notable, a fainter part running ENE to WSW appears to be discernable, just before the start of the fainter SE part of the nebula, as an separation between the NW and SE part of the nebula.
OIII: When using this filter an interruption appears to be visible, too, to the south of the knot in the NW part. UHC: Using this filter the interruption that appeared to be visible using the OIII filter is not visible, the knot remains notable.
A quick Google search for images reveals both the bright knot and a dark separation in both the knot and between the NW and SE parts of the nebula. A nice and rewarding observation indeed!
Victor, I can put in two sketches, one with the 16" as a comparable aperture and one with the 27". Beside the brighter knots or better the dark lane you can find a bright halo around the PN. Perhaps you have seen it also. In the past I always thought that the brightening around the PN was because of the brightness of the PN and the stray light around it but it is for real the halo.
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