My First Non-Stock Eyepieces - Badder Hyperion

[CaptainKingsmill]

I've just invested in my first 2 eyepieces that didn't come stock as part of a telescope.
Despite owning a telescope in some form for many years, being more of a photographer than a visual viewer i've never seen fit to use my funds for visual stuff despite knowing my eyepieces were crap. - But I dropped my trusty 20mm Plossl and bust it up so it was finally time.
After a bit of looking around I settled on the Hyperion 68, I picked up a 10mm and a 21mm for now and I'll probably expand that as and when funds allow. 

.....My goodness they're HUUUUGE!! 

I'm not sure what I was expecting, but having no frame of reference and only ever using stock plossl's I just assumed that they would be similar in size just with better optics or something, How wrong was I.

But anyway, I'm very impressed with the build on these, and now just can't wait to get an opportunity to get out any use them, which feels like never with the weather at the moment. 

 

[Louis D]

The Hyperion line is more or less a lower cost, Chinese interpretation of the Japanese Vixen LVW eyepieces.  A comparison by our own @John of the two lines can be read here.

Both lines, along with the Pentax XL/XW, Baader Morpheus, Tele Vue Delos, Omegon Redline, and several other lines, use a two stage eyepiece design.  First, they all use a long focal length, positive upper section that forms the image seen by the eye.  It has both long eye relief and a 65 to 76 degree apparent field of view.  Second, they all use a negative lower section similar to a Barlow or Smyth lens that magnifies the incoming image for presentation to the upper section.  The larger upper section remains relatively unchanged across focal lengths, decreasing manufacturing costs while maintaining a similar viewing experience through each variation.  It is the lower, negative section that varies wildly from focal length to focal length.  Some of the most advanced designs actually use an intermediate lens group between the two sections to further refine the image correction.

Here's a diagram of the older Pentax XL line:

Ignore the XL40 design, it was a unique 2" design.

Here are two diagrams of the Pentax XW line:

Again, ignore the XW30 and XW40 designs as they are unique 2" designs.  Even then, it's clear the 30mm has a weak negative section feeding a near copy of the 40's positive section.

Take note of how similar the 1.25" eyepiece positive sections (the bigger ones on the right in each diagram made up of four lenses in 3 groups) are across all focal lengths.  Only the 20mm/21mm/28mm versions vary a bit in the field (left-most) lens of the positive group.  The other two groups remain basically unchanged, keeping down manufacturing costs.

Now notice how wildly different each negative section (the smaller ones on the left in each diagram) vary from focal length to focal length.  The shortest focal lengths actually split it into two groups to create what appears to be a telecentric magnifier like a Tele Vue Powermate (left-most group magnifies by divergence, right-most group brings the light bundle back together again, but at higher power).  This allows for high magnification without sending wildly diverging beams into the positive section.  Wildly diverging incoming beams can cause vignetting and eye relief extension, among other issues.

Also notice how the 7mm, 10mm, and 14mm XW versions each have an intermediate lens group not found in the earlier XL designs.  I believe they were added to improve field correction in going from 65 degrees for the XL line to 70 degrees for the XW line.

The upshot of all this is that to maintain long eye relief and wide field of view requires a large positive section with a somewhat distant negative section feeding it a magnified view.  This results in a rather large eyepiece as you discovered.

[CaptainKingsmill]

Thank you for such a detailed explanation of the reasoning. 

very interesting indeed! I've read that these EP's perform better with slower scopes, with some claiming they shouldn't go anywhere near anything faster than F5 so I'm interested to see if my amateur eye can tell the difference when I test it in my F5 newt vs my F9.8 refractor. 

I got a very brief window to use them last night for the first time, and the views are simply miles ahead of the my stock lens! 
Beautiful views of Jupiter before the cloud and fog rolled in,

[Mr Spock]

The stock eyepieces are usually inexpensive to manufacture and are there to get people started. They should always be the first upgrade. I'm sure you'll get a lot of enjoyment out of your Hyperions - they are a good eyepiece.

I use the LVWs. They are great at the f4.7 of my Dob. If one comes up for sale second hand they usually get snapped up in seconds!

[John]

3 hours ago, CaptainKingsmill said:

Thank you for such a detailed explanation of the reasoning. 

very interesting indeed! I've read that these EP's perform better with slower scopes, with some claiming they shouldn't go anywhere near anything faster than F5 so I'm interested to see if my amateur eye can tell the difference when I test it in my F5 newt vs my F9.8 refractor. 

I got a very brief window to use them last night for the first time, and the views are simply miles ahead of the my stock lens! 
Beautiful views of Jupiter before the cloud and fog rolled in,

Try observing an extended object such as the double cluster in Perseus at a magnification where both clusters are in the same field of view. This will show up star definition across a wide expanse of the field of view so will show any distortion being added by the eyepiece (eg: astigmatism) or the scope (eg: coma which faster newtonians generate). Sometimes you get a mix of distortion types, which can be hard to diagnose. This link is quite useful:

http://websites.umich.edu/~lowbrows/reflections/2007/dscobel.27.html

 

[Voyager 3]

Astimagtism and coma are aberrations , while pincushion and barrel are distortions . 

[John]

6 hours ago, Voyager 3 said:

Astimagtism and coma are aberrations , while pincushion and barrel are distortions . 

Apologies - sloppy wording from me !

 

Edited November 16, 2021 by John

[Voyager 3]

Ha , no apologies , as I'm no greater . You have to read my English to know the meaning of sloppy . 

[RobertI]

On 12/11/2021 at 20:20, CaptainKingsmill said:

I've just invested in my first 2 eyepieces that didn't come stock as part of a telescope.
Despite owning a telescope in some form for many years, being more of a photographer than a visual viewer i've never seen fit to use my funds for visual stuff despite knowing my eyepieces were crap. - But I dropped my trusty 20mm Plossl and bust it up so it was finally time.
After a bit of looking around I settled on the Hyperion 68, I picked up a 10mm and a 21mm for now and I'll probably expand that as and when funds allow. 

.....My goodness they're HUUUUGE!! 

I'm not sure what I was expecting, but having no frame of reference and only ever using stock plossl's I just assumed that they would be similar in size just with better optics or something, How wrong was I.

But anyway, I'm very impressed with the build on these, and now just can't wait to get an opportunity to get out any use them, which feels like never with the weather at the moment. 

 

Hyperions were my first step up from the standard eyepieces that came with my C8, and they are I still my main eyepieces ten years later! Not sure why I have not upgraded further, I guess I’m not that fussy, they generally just work and are very pleasant to use. The 10mm is my workhorse. I really do want to experience some premium eyepieces at some point, just not sure what focal length I would need and what brand/model to get. 🤔 Anyway enjoy your Hyperions. 👍

[LDW1]

On 12/11/2021 at 15:20, CaptainKingsmill said:

I've just invested in my first 2 eyepieces that didn't come stock as part of a telescope.
Despite owning a telescope in some form for many years, being more of a photographer than a visual viewer i've never seen fit to use my funds for visual stuff despite knowing my eyepieces were crap. - But I dropped my trusty 20mm Plossl and bust it up so it was finally time.
After a bit of looking around I settled on the Hyperion 68, I picked up a 10mm and a 21mm for now and I'll probably expand that as and when funds allow. 

.....My goodness they're HUUUUGE!! 

I'm not sure what I was expecting, but having no frame of reference and only ever using stock plossl's I just assumed that they would be similar in size just with better optics or something, How wrong was I.

But anyway, I'm very impressed with the build on these, and now just can't wait to get an opportunity to get out any use them, which feels like never with the weather at the moment. 

 

I just built up a set of 6 plus one Morpheus, they are great eye pieces, I use them in 6 various size refractors f6 - f11.4