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John

New Orion (USA) 80 Degree Range

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22 hours ago, 25585 said:

Have the 20mm Orion now. Due for a test against a Celestron 22mm Ultima LX (also 2 inch) 70 deg and my new Takahashi 28mm Erfle, which is 1.25 inch fit. All 3 have very close AFOV, but in the Tak's case less magnification.

The Orion 14mm is also 2 inches, but has a smaller FOV than APM's 13mm 100 deg, both prices close enough to consider either. Usable eye relief and bean/cut-off-free less exact positioning would be the deal maker for me. 

How are you finding these? I originally bought the 20mm because it was "all I needed" to fill a gap in the collection but after using it to resolve a few double stars and look at the moon I realised "all I needed" was the 14mm to get a bit extra from the viewing. I then decided that if I just got the 9mm as well I could get rid of some of my older EP's....

After looking at Jupiter last week and watching Europa transit across I just needed the 6mm to complete the collection!

They're big and heavy but I think they give some stunning views and the 20mm is my favourite.

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Looked at M13 through mine. Low mag 25x as in my 500mm TV Genesis but very chuffed, though if eye relief is OK I'm lenient on other optical issues. Got to try in a different scope for more analysis. Not sure if actually 80 deg AFOV as I don't know how to measure that or TFOV either. 

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3 hours ago, 25585 said:

Not sure if actually 80 deg AFOV as I don't know how to measure that or TFOV either.

The projection method with a flashlight (torch) and using a bit of trigonometry that I've described elsewhere on SGL is the most accurate way to measure AFOV.

Edited by Louis D
clarified answer
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Took a chance on a new 4mm LHD at 180$ three weeks ago (amazon us). Unfortunately weather since then is terrible. So if it becomes better(and it got to because of the 0.8mm exit pupil and 380x on my 12inch dob) I'll try a review. At the moment I only can confirm that it is heavy glass but well processed.

Clear skies

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Actually I did some measurements and calculations. In several attempts I've determined a FOV of roundabout 83 degrees(82 with fully-lifted eyecup, 84 in its lowest position). The eyelens-diameter is indeed 30mm. Together this yields a calculated eyerelief of ~17mm. Its concave eyelens got a depth of 3.5mm. All in all the eyerelief is indeed roundabout 20mm.

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7 hours ago, san andreas said:

Actually I did some measurements and calculations. In several attempts I've determined a FOV of roundabout 83 degrees(82 with fully-lifted eyecup, 84 in its lowest position). The eyelens-diameter is indeed 30mm. Together this yields a calculated eyerelief of ~17mm. Its concave eyelens got a depth of 3.5mm. All in all the eyerelief is indeed roundabout 20mm.

Is it usable with eyeglasses?  I just picked up a used 22mm NT4 and measured the usable eye relief at 16mm, but it feels more like 14mm with eyeglasses since I have to really cram them deep into my eye socket to see the field stop.  Needless to say, I'll be living with less than the measured 85 degree AFOV in a single view since I'd be constantly pushing the scope off target or vibrating it excessively.  It has a 30mm eye lens yielding 16.5mm of calculated usable eye relief.  I'll be comparing it to my 22mm AstroTech AF70 to see which I prefer in the long run.  The NT4 may have different characteristics at night when my pupil is fully dilated.  Based on an artificial star, there's a tiny amount of astigmatism, chromatic aberration, and field curvature in the last 10% at the edge.  Since I can't see the edge easily with eyeglasses, this may not be an issue for me.

One of the two 22mm eyepieces will live on in the A-team case, the other will be relegated to the B-team case.

I had hoped for a 22mm to 25mm ES-92 by now, but it doesn't appear to be in development at the current time based on the latest rumors on CN. 

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Hi Louis, I use to observe with contact lenses, but I'll think on a try with my glasses as soon as i can start a firstlight. By the way I also own a 22 NT4 and it's a real keeper?

Edited by san andreas

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I compared the 22mm NT4 on the Orion complex against the 17mm ES-92, 24mm APM UFF, 27mm Panoptic, 30mm APM UFF, 35mm Baader Scopos Extreme, and 22mm AT AF70 in my field flattened AT72ED.  The biggest surprise was that it was the most difficult to get it to snap to focus of the 7 eyepieces.  It was sharply focused when that point was found, but the out of focus stars were spiky rather than fuzzy as in the rest.  That, and I had to refocus for the edge indicating field curvature.  Despite refocusing, there was really noticeable astigmatism (not subtle at all).

  1. I really couldn't take in any more TFOV with the 22mm NT4 than with the 17mm ES-92 due to the lack of usable eye relief.  Stars were also much sharper to the edge without no refocusing needed in the ES-92.  Win definitely went to the ES-92 in that head to head despite the two costing within $30 of each other new here in the states.
  2. The 24mm APM UFF had a much more pleasingly sharp image across the entire field despite having a narrower AFOV.  Again, it didn't give up much TFOV to the NT4 due to the latter's lack of usable eye relief.  For a 1.25" eyepiece, it held its own surprisingly well.
  3. The 27mm Panoptic had almost exactly the same TFOV and for once, it had the better eye relief, so it appeared to show more field than the NT4.  I could just take in the entire field without pushing my glasses into my face.  Again, the field was sharper edge to edge without refocusing in the Panoptic.  The AFOV just feels narrow at 68 degrees.
  4. The 30mm APM UFF showed way more TFOV than the NT4 or Panoptic, was sharp to the edge, and easy to take in with eyeglasses.  Definitely a growing favorite of mine.
  5. The 35mm Scopos is incredibly sharp and constrasty in the center 75% of the field of view, possibly more so than the 30mm APM UFF.  It is difficult to see the last 20% without tipping your head to align ones eyeglasses properly to avoid inducing astigmatism into those edge stars.  However, it was splitting the Trapezium into 3 bright stars at 12x all the way to the edge once properly aligned.  The 30mm APM UFF was close without any contortions.  The biggest downfall to this eyepiece is the 64 degree AFOV which feels very narrow in comparison to most of this field of eyepieces.
  6. The 22mm AF70 was no worse astigmatism wise relative to the NT4.  It seemed just as sharp in focus and had a much flatter field than the NT4.  The NT4 was showing more field without pressing my eyeglasses into my face, so it might have the win here.  I'm still undecided and will have to try each out in the Dob with the coma corrector.

Overall, I was bit underwhelmed by the 22mm NT4.  I was expecting to be blown away by TV perfection equaling the ES-92, but was instead treated to difficult focus, astigmatism growing from 70% out to unacceptable levels by the edge, and noticeable field curvature.  It was better at controlling edge of field brightening than the AF70, but it also costs 4.5 times as much.  However, the ES-92 had near next to no EOFB at all.  The Orion nebula was distinct and separated from the background to the edge whereas it faded away in the NT4.  I'll hang onto the 22mm NT4 for now and keep comparing it to see if it grows on me.

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I tried out the same eyepieces as above in my 8" f/6 Dob with GSO CC last night.  The most notable difference was the nearly complete lack of edge of field brightening in any eyepiece!  I have no idea if it was the sky conditions or the telescope type making the difference.  The Orion nebula was distinct to the edge in pretty much everything.

The other notable difference was that I was easily able to take in the entire AFOV of the 22mm NT4 in the Dob where I struggled in the frac.  I popped in the 17mm NT4 as a double-check; but no, I still can't take in the entire AFOV with eyeglasses with it.  The 22mm really does have more usable eye relief than the 17mm.

I also noticed that because I have to focus so far inward for the 22mm NT4, it throws off the coma correction.  I'd have to remove the spacer and try again to see if it improves.  This isn't much of a long term solution, though.  As a result, I deferred on making any judgement calls about it's edge correction.  I tried it without the CC, and the view was so miserable, I moved right along.

I added the 30mm ES-82 to the mix to recheck center sharpness, and while it works great on dim stars, the dimmest stars seem to disappear altogether as in the Double Cluster.  They are quite visible in the 30mm APM UFF, but barely detectable with great effort in the ES-82.  So I stand by my original conclusion that the ES-82 fails to achieve as sharp a central focus as other 30mm eyepieces that are available.  Those stars were also quite visible at lower power in the 35mm Baader Scopos which, once again, is incredibly sharp and contrasty in the inner 75% of the FOV.  I also didn't have to play games at the edge to avoid astigmatism with that eyepiece in the Dob as with the frac.

The 24mm APM UFF looks really narrow in this company, but it still delivers a wide TFOV with excellent edge to edge sharpness with very little field curvature.  The only wierd thing is the fuzzy edge when used with the CC that goes away when used natively in the Dob.

The 27mm Panoptic reminded my why I've kept it.  It still delivers a very sharp and wide view from edge to edge with very little field curvature.

Once again, the 17mm ES-92 was the star of the show.  Wide TFOV appearing to be about the same as the 22mm NT4, sharp focus everywhere, high contrast, and easy to take in the entire view with eyeglasses.  The 12mm ES-92 was just a bit too much power for most objects I viewed (Orion complex, Pleiades, and Double Cluster) to be pleasing.  Otherwise, it views about the same as the 17mm.

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Öhm, since I've repeated the measurements on the ORION LHD 80 4mm with more accurate tools I have to apologize for some mistakes:

1. AFOV is 80°

2. eyelens-diameter is 30mm

3. concavity of the eyelens is 2.5mm

so calculated eyerelief is 17.9+2.5=20.4mm

Hope you can forgive therefore?

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