ES 9mm 100° doesn't like my barlow

  1. Benjamin
    Benjamin
    Had a check tonight of a few things which have been bothering me. My 30mm 82° has a little field curvature and I wanted to see how much I'd exaggerated in my mind. It turns out it was highly exaggerated. Stars are good to the edge and if I focused in about half way between middle and edge everything looked more than fine. Then I wanted to reaffirm that the 9mm 100° was terrible with my GSO ED 2x Barlow. It was! Even if I screwed off the end and magnified 1.5x (200x) with a 1mm exit pupil it sucked (dark, dull image). I thought maybe too much glass (9mm fine on its own) but when I tried the 14mm with the barlow the results were amazing and easily compared to the 6.7mm 82°. I was using Saturn as the testing object. I also compared the 4.7mm 82° and this eyepiece provided great results although at 255x it was pushing limits. I've tended not to use barlows but was keen to see if I could extend the 100° views at higher mags. Wonder if others have had the same experience with the 9mm?
  2. Benjamin
    Benjamin
    Actually, ignore this thread. Tried again the 9mm with both the 1.5x screw on and the 2x Barlow and everything worked well. I assume it was an aberration in seeing somehow: something to do with staring too long at a very bright Saturn. I found as soon as I gave my eye a rest or looked around the eyepiece more the dullness dissipated. It is a darker eyepiece too and is one of the few eyepieces I have to rack out a long way to get into focus (unlike the 14 and 20). Clear skies to all.
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