Imput requested

[Guest]

Has anyone given this eyepiece a try?  Basically it is a  Long Perng eyepiece with Orion's name on it.  Thinking about trying one in a 10 in f5 dob.

[Don Pensack]

I have, and extensively compared it with a 14mm Baader Morpheus and several other eyepieces at a dark site (m.21.4+ skies)

It has some issues:

1) It does not have 20mm of eye relief with the threaded-on eyecup provided.  That eyecup sticks up about 8mm above the lens, reducing the eye relief to about 12mm.

That would be fine if you don't use glasses at that focal length.  Unfortunately, I do, and it was inadequate for glasses use.

Removing the eyecup exposes your glasses to being scratched by the aluminum top of the eyepiece.  The thread is 50mm, so finding an eyecup to fit isn't going to be easy.

I stretched a smaller eyecup onto the eyepiece and folded the rubber inward to cover the aluminum top of the eyepiece with rubber about 0.5mm thick, and the eyepiece was usable with glasses at that point.

2) The eyepiece has some highly reflective surfaces inside the eyepiece and the eyepiece has some edge of field brightening I did not see in the Morpheus.

 I took the LHD eyepiece apart and blackened the internal spacers, lens edges and housing and this reduced, but did not eliminate, the edge of field brightening.

I communicated with LongPerng about it, but they admitted the eyepiece had a bit of a problem with scattered light but that they were "working on it to do better".

 

Other than those two issues (I kept the 14mm Morpheus and gave away the LHD), the eyepiece is nice and sharp to the edge.  Color rendition is good, and the eyepiece works fine

at f/4.5.  It's a very modern eyepiece, but I have to admit to being mystified why someone would design an eyepiece with enough eye relief for glasses and then put it in a housing that eliminates

its suitability for glasses, and that applies to the entire series.  I guess the outer shell designers paid no attention to the results of the optical designers.

[Guest]

3 hours ago, Don Pensack said:

I have, and extensively compared it with a 14mm Baader Morpheus and several other eyepieces at a dark site (m.21.4+ skies)

It has some issues:

1) It does not have 20mm of eye relief with the threaded-on eyecup provided.  That eyecup sticks up about 8mm above the lens, reducing the eye relief to about 12mm.

That would be fine if you don't use glasses at that focal length.  Unfortunately, I do, and it was inadequate for glasses use.

Removing the eyecup exposes your glasses to being scratched by the aluminum top of the eyepiece.  The thread is 50mm, so finding an eyecup to fit isn't going to be easy.

I stretched a smaller eyecup onto the eyepiece and folded the rubber inward to cover the aluminum top of the eyepiece with rubber about 0.5mm thick, and the eyepiece was usable with glasses at that point.

2) The eyepiece has some highly reflective surfaces inside the eyepiece and the eyepiece has some edge of field brightening I did not see in the Morpheus.

 I took the LHD eyepiece apart and blackened the internal spacers, lens edges and housing and this reduced, but did not eliminate, the edge of field brightening.

I communicated with LongPerng about it, but they admitted the eyepiece had a bit of a problem with scattered light but that they were "working on it to do better".

 

Other than those two issues (I kept the 14mm Morpheus and gave away the LHD), the eyepiece is nice and sharp to the edge.  Color rendition is good, and the eyepiece works fine

at f/4.5.  It's a very modern eyepiece, but I have to admit to being mystified why someone would design an eyepiece with enough eye relief for glasses and then put it in a housing that eliminates

its suitability for glasses, and that applies to the entire series.  I guess the outer shell designers paid no attention to the results of the optical designers.

Thanks for the input I appreciate it.  I do wear glasses for reading.  The come off when I am looking through the eyepiece.