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H-ortho (Highly Othoscopic) eyepiece


markse68

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In another thread Gerry posted a very interesting chart of eyepiece optical designs and their ray tracing analysis taken from this webpage:

https://www.telescope-optics.net/eyepiece_raytrace.htm

5A6A079A-B75B-4909-B913-A168A3B7FE6E.png

Despite not really understanding what I was looking at (what do those ray trace patterns (splodges) mean- worst aberrations? need to do more research!) I noticed a schematic for a type of eyepiece i’d never heard of- #9 in the chart- the H-ortho.

32BF79FB-BE4E-4E76-95C8-6760C2E73E7C.jpeg

1DDBADAD-D7A5-4A11-8C3F-57C52BDA26CE.jpeg

This seems to be a variation on the Abbe design- still 4 elements in 2 groups but the triplet is quite different. The ray trace seems to suggest it is sharper for wider than the Abbe- if i’m reading it right, and presumably it is better corrected for distortions too, hence the name.

This is what the page has to say:

”9 - The "highly orthoscopic", or H-Ortho has somewhat different triplet configuration, resulting in a highly corrected field, similar to that of the monocentric eyepiece, only significantly wider. In part, this exceptional of field astigmatism correction is a trade off for the significantly curved best image surface. However, while the standard orthoscopic would also have astigmatism reduced with more strongly curved best field, it doesn't seem it could achieve the same level of correction.”

Anyway, google turns up a complete blank on this design. Anyone heard of it before? Is it just theoretical or do they exist? Maybe as a microscope ep? Did the curved field put the kibosh on the design?

Edited by markse68
typo
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5 minutes ago, johninderby said:

A pic or the Hi-Or 4mm.

382919D2-3E0C-417C-AF61-47E9045E3B00.jpeg

yea but it’s not an h-ortho 😉 not the same thing at all from reviews i’ve read- they used a built in barlow to give decent eye relief as it would have been impossible to use at those fl otherwise- hi= high eyepoint (not highly orthoscopic)

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5 hours ago, markse68 said:

Despite not really understanding what I was looking at (what do those ray trace patterns (splodges) mean- worst aberrations?

The spot diagrams show a star image at best focus (I think it ignores curved focal planes) in an f/5 system.  The black is simply a green wavelength since it's in the middle and our eyes are most sensitive to green.  The red/blue plots show chromatic effects on the image.  Horizontally, you are moving from center (axis) to edge.  The degree increments vary by actual field width. The ExP numbers refer to exit pupil separation at midfield and edge.  The greater the difference, the greater the SAEP (kidney beaning).  Normally a circle of known size is drawn around each plot for scale so you can judge whether or not the aberrations would be visible to the eye.  However, they are missing from those plots and is only shown at the top.  Here's another set of plots from the webpage previous to the linked image with more discs shown:

spacer.png

In these, the center color is explicitly shown as green instead of black.  The plots are also shown for f/10 and f/5 systems so you can compare the performance as the scope places more stress on the design.

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This diag points out why I was separating the true Plossl from the achromat pair... we can see what happens to the colors and spot size as we veer off axis. This really does show why I like orthos- excuse me I better be specific- Abbe ortho lol! as we all know that orthoscopic is not a design but a condition :grin:

Even the beloved very narrow monocentric suffers "bigly" off axis. I'll take an Abbe any day.

Never heard of the H orthos being around- true ones.

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45 minutes ago, jetstream said:

This really does show why I like orthos- excuse me I better be specific- Abbe ortho lol! as we all know that orthoscopic is not a design but a condition :grin:

Even the beloved very narrow monocentric suffers "bigly" off axis. I'll take an Abbe any day.

would be interesting to see comparison plots for the Pentax XO design which appears to be a very carefully executed, corrected plossl (to my ignorant eyes ;))

07236880-4EBF-4BAE-ADF0-91E4A32C0A66.jpeg

Edited by markse68
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26 minutes ago, markse68 said:

don’t we all! 😉 Maybe we should petition Ricoh to re-release them 🤔

I think that has been done quite a few times by our friends in the USA. They are like hens teeth to find pre-owned, even the 2.5mm.

I guess the Vixen HR's are the nearest we have today that are at least vaguely obtainable ?

 

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11 minutes ago, John said:

I think that has been done quite a few times by our friends in the USA. They are like hens teeth to find pre-owned, even the 2.5mm.

I guess the Vixen HR's are the nearest we have today that are at least vaguely obtainable ?

 

Or the TOE’s? Were they petitioned about the 2” XWs do you know John?

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1 minute ago, markse68 said:

Or the TOE’s? Were they petitioned about the 2” XWs do you know John?

Don't know about the 2" XW's. Personally I don't think Ricoh are that bothered by the astro market and consumer demand from it :dontknow:

The TOE's do have a great reputation.

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33 minutes ago, jetstream said:

Maybe they should make some Pentax XO design eyepieces- are they patented?

it’s only one extra lens by the look of it 😉😂 very similar approaches to stray light control 👍

54264D6D-CB60-4167-865E-4DBF6AB6847E.png

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3 hours ago, mikeDnight said:

Looking at the engineering that's gone into the HR body as well as the obvious high quality of the optical components, its a wonder their cost isn't much higher. It makes me love them even more.

When they go out of production their cost will be much higher !

 

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I guess if Don hasn’t come across this design in reality then it must be theoretical. I’ll try contacting the author of that website or maybe Chris Lord. There are a few archaic designs I’ve seen mentioned like the single solid element types that don’t seem to exist except maybe in museums-seems odd though when this one seems to offer real benefits 🤷‍♂️

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I guess there will be some designs that never made it into production and some that were intended for a very specific purpose, maybe military, so we don't see them ?

 

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7 hours ago, markse68 said:

I guess if Don hasn’t come across this design in reality then it must be theoretical. I’ll try contacting the author of that website or maybe Chris Lord. There are a few archaic designs I’ve seen mentioned like the single solid element types that don’t seem to exist except maybe in museums-seems odd though when this one seems to offer real benefits 🤷‍♂️

Could have been some made.  Timing is everything where sales are concerned.

The Takahashi Hi-LE eyepieces (2 focal lengths) were Abbe orthoscopics with 2 element barlows added in the bottoms.  They're now out of production.

An improved design for the Abbe ortho is a nice idea for the modern world, where edge sharpness is more valued.

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