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Subject: Re: vote by xxx.xxx.169.37
By: Anonymous (xxx.xxx.86.249)
In Reply to: Anonymous (xxx.xxx.169.37) (Original Vote)
Date: 02/09/2003 04:40:42 pm PST
Recently, I tried out one version or another of all Orion's new sub-Ultrascopic priced eps - Expanse, DeepView and ED2's. All had one optical problem or another - on axis coma and off axis astigmatism (DeepView), off axis coma and astigmatism at field edge (Expanse) off axis coma (12.3mm ED2). The Expanse and Deepview had problems with extra-field stray light either reflecting around through the barrel, or as a result of light strking the field lens and obscuring field contrast. The ED2 was free of off-axis reflections (more or less) and had optics perhaps a tad sharper than the Expanse but not quite as sharp as the Ultrascopics. The ED2 (12.3mm) had superior edge correction to the Expanse (no astigmatism, minimal coma) - but I was operating at higher magnifications.
Basically I kept the ED2 and returned the others. The ED2 came closest to the Ultrascopics in all aspects of performance but seem to be slightly "softer" - although quite acceptable in terms of clarity.
The ED2 shows some "kidneybeaning" so eye position is more critical than through the Ultras (even more than the 25mm version of the Ultra.)
Finally you should keep in mind that the Ultras are 40 dollars more expensive.
Of all the eps tried only the ED2 came close to being an acceptable lunar-planetary eyepiece. The Expanses however would make satisfactory deepsky eps. Especially with their 65 degree plus AFOV.
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