The theme for the evening was suggested by @Lady Fraktor who noted that the Antares version of the 15mm pseudo Masuyama seemed to have less scattered light than the Orion version. The Antares was marketed as an ‘Elite’ Plössl while marketing for the Orion called it an Ultrascopic. Both are based on the Zeiss Astroplan design.
So, the equipment for this session consisted of:
Orion SS IV mount
Orion EZ Finder
TeleVue 27mm Panoptic, magnification = 21, TFOV = 3.3 deg, exit pupil = 3.9,
Orion 15mm Ultrascopic, magnification = 37, TFOV = 1.43 deg, exit pupil = 2.1,
Antares 15mm Elite Plössl, magnification = 37, TFOV = 1.43 deg, exit pupil = 2.1,
Inspection prior to setup showed the Antares and Orion to have identical appearance except for brand marks. In their ongoing efforts to discourage my observing, my back neighbor has severely cut back the branches on the two trees that provided some shade from their floodlights. Apparently budgetary constraints (?) prevented removal of the tree trunks so I was still able to find a shaded micro area from which I could see Polaris. Set up aligned on Altair and Polaris.
I’m a great believer in impulse response functions (
) so my first comparison of the 15mm eyepieces involved Vega and looking carefully at the extent of the scattered light compared to the separations from nearby stars. I could occasionally talk myself into there being a slight difference with the Antares being a tad better, but it seemed that the intensity of the scattered light was less though the extent was the same. I noticed that the Antares and Orion are just a touch not parfocal with each other. This is not a surprise, focal lengths of eyepieces from the same plant have minor differences. Achieving foces with one or the other while swapping required just the smallest nudge on the focuser.A better test would be provided by Jupiter which was not yet clear of an apple tree to the east. So I entertained myself with the 27mm Pan and viewed:
M57, the Ring Nebula, found in the 27mm and better with the 15mms
M13, the Great Cluster in Hercules
M39, an open cluster in Cygnus
The Double Cluster in Perseus
The
The Dumbbell, M27, a planetary in Vulpecula
The dumbbell or apple core shape was well seen. However, the sky background was noticeably brighter than in the past, for this and all the other
Finally, Jupiter cleared the apple tree. At first only the big three Galilean moons were visible but then Io cleared the disk later. The difference in the two 15mm eyepieces was most marked in viewing Jupiter’s equatorial cloud bands and polar caps. The Antares provided definitely crisper views with deeper color saturation than the Orion version. It was now getting on from 3am so I declared victory and ended the session.
