jm-fluo

Anciens oculaires

Recommended Posts

Posted (edited)

Bonjour les astrams

 

Testé ce matin trois OR coulant 24.5mm sur les taches solaires avec un filtre verre  ND5Thousand Oaks optical sur la Vixen 102M sans filtre de couleur.

  • OR double circle V Vixen 6mm
  • OR Carton 6mm A (don de @lyl)
  • Stellarion OR HD 6mm

 

Première constatation: les deux premiers sont parfocaux dont il est fort probable qu'il s'agisse de versions 2+2. La définition est équivalente.

La mise au point est différente avec le troisième, mais la douille 24.5mm et la position du bloc optique est différente.  La définition est équivalente aux deux premiers. Dans les trois cas, le visuel était assez mauvais, même si j'ai pu observer les taches solaires les plus petites. Le filtre verre n'est pas ce qu'il y a de mieux mais il offre la sécurité et la durabilité. 

 

A suivre....

 

ClaudeS

 

  • 17165423623173652058973103219378.thumb.jpg.62a863bd2873086d5d931b29af8103a5.jpg
Edited by ClaudeS

Share this post


Link to post
Share on other sites
Posted (edited)
il y a 19 minutes, ClaudeS a dit :

Première constatation: les deux premiers sont parfocaux dont il est fort probable qu'il s'agisse de versions 2+2

Le Carton est un true Abbe 3+1, j'ai démonté.

Les conditions chez moi sont très mauvaises aujourd'hui et globalement il y a des perturbations partout, je n'ai même pas pu observer la Lune hier soir à la 60mm, ça ne présage rien de bon.

Vixen peut avoir utilisé du 2+2 comme du vrai Abbe. Il ne faut pas avoir de préjugé sur les versions, ça dépend grandement du talent de celui qui monte le triplet quand c'est un Abbe, Il y a des moyens, des corrects et des excellents.

Carton a fait des excellents plössls asymétriques et des Abbe de différentes qualités.

Vu le nombre que j'ai cotoyé, les valeurs sûres du point de vu fabrication sont Zeiss, Leitz, Pentax (fait en interne), Nikon (Ohi Optical ou en interne), Tani (Ohi Optical mais pas que)

Edited by lyl
  • Like 2

Share this post


Link to post
Share on other sites
Il y a 1 heure, lyl a dit :

ça dépend grandement du talent de celui qui monte le triplet

Bonjour Myriam,

 

Qu’entends tu par monté le triplet ? Polissage des verres? Placements des lentilles? Car dans ce cas là, peu de risques de se tromper étant donné que chaques lentilles à son emplacement avec les spacers! Je me trompe sûrement, je ne demande qu’à comprendre😉

Share this post


Link to post
Share on other sites

Il s'agit du collage des trois verres du triplet. Cela semble assez critique sur les courtes focales pour le centrage. Je ne me souviens plus où je l'ai lu. De ce fait là une préférence pour les doublés collés.

  • Like 1

Share this post


Link to post
Share on other sites
il y a une heure, Milkomeda a dit :

Qu’entends tu par monté le triplet ? Polissage des verres? Placements des lentilles? Car dans ce cas là, peu de risques de se tromper étant donné que chaques lentilles à son emplacement avec les spacers! Je me trompe sûrement, je ne demande qu’à comprendre

Il n'y a pas d'ambiguïté, monter un triplet collé comme l'indique ClaudeS c'est aligner les lentilles lors du collage, j'ai posté au fil du temps plusieurs articles sur le sujet.

 

Par exemple, de la commission des instruments de la SAF, ce problème est à l'origine de la création des plössls Clavé

ou l'ancien président de Vixen qui justifie l'abandon des orthoscopiques Abbe pour la production en grande série et l'adoption de la formule Abbe duplet symétriques (ou des plössls assymétriques chez Carton).

 

Je vous mettrais en PJ dans ce message des passages clefs, vous comprendrez pourquoi les orthoscopiques ont une telle différence de prix, justifiée par les performances supérieures quand on les utilisent à f/D plus courts et de manière générale d'autres critères.

De façon générale les plössls modernes (Televue compris) fonctionnent correctement entre f/D 10 à 16 et les orthoscopiques descendent jusqu'à 8 en utilisant les critères complets, pas seulement le piqué central ou le bord mais tout le champ visuel nominal. 

  • Like 2
  • Thanks 1

Share this post


Link to post
Share on other sites

Je comprend mieux, merci beaucoup 👍

c’est vrai que l’alignement des lentilles est essentiel en optique afin de réduire au maximum toutes formes d’aberrations mais j’imagine que les personnes pratiquant cette activité doivent avoir des outils et ordinateurs leur permettant d’atteindre les critères demandés pour un excellent Orthoscopique, ils ne font pas cela à main levée 😁

Share this post


Link to post
Share on other sites
Posted (edited)
Il y a 5 heures, Milkomeda a dit :

ils ne font pas cela à main levée

Sisi ! mais il faut avoir la main sûre et un timing de précision.

 

La SAF de 1949 à 1954, le projet orthoscopique puis la naissance du Clavé.

SAF-oculaire1.JPG.8538c372a33cb8155db4710005d652f8.JPG

 

SAF-oculaire2.JPG.b8c2c0e4b7d0a47039ef294ae8e3d3ce.JPG

 

SAF-oculaire4.JPG.7f8212adbb15eb28c911e7a58018e2e0.JPG

 

SAF-oculaire7.JPG.12155a9b9f0ce176ec35b7363d81a38e.JPG

 

SAF-oculaire9a.JPG.e89f61677fe5afbdca745b5c13bb95eb.JPG

SAF-oculaire9b.JPG.48b3dfa3c121da6327497fede16de5c6.JPG

SAF-oculaire9c.JPG.41b65b7b288f74cb7418299c8cf967f9.JPG

 

Edited by lyl
  • Like 1

Share this post


Link to post
Share on other sites
Il y a 3 heures, lyl a dit :

les orthoscopiques descendent jusqu'à 8 en utilisant les critères complets, pas seulement le piqué central ou le bord mais tout le champ visuel nominal. 

Même jusqu'à 7 avec la TEC180 FL :-)

Share this post


Link to post
Share on other sites
Posted (edited)
Il y a 4 heures, jm-fluo a dit :

Même jusqu'à 7 avec la TEC180 FL :-)

Pas sûr que la TEC 180 ne vienne modifier la spécification très stricte de Zeiss pour parler du niveau du ZAO de 1994, mais on voit plus loin dans la réponse d'Aki Saito que f/6 est dans la norme d'utilisation et même plus bas pour le joyau de 4mm.

image.png.0f22ce90a57344a14f7955c06d37017b.png


A l'époque vintage (~1955-1985), les séries étaient complètes.

Vixen.jpg.3d1b8c1d7bf9c6980d160af220671127.jpg

De Roland Christen, qui connaissait bien vu ses accointances avec Bausch & Lomb.

Les premiers, les plus anciens orthoscopiques sont conçus pour f/20.

ZeissOrthos.JPG.d2ad825e32e5ea0fc58474c302072eb5.JPG

La période intermédiaire les place à f/10 et je rajoute f/7.7 (source Uwe Laux, Astrooptics) et mes rétro-conceptions sur CN section ATM & DIY, le sujet agrafé sur les conceptions.

AbbeCZJOrthos.JPG.fad7ec4ffeecc77ad06e19d9b956e98c.JPG

Un autre avis éclairé.

AbbeOrthos.JPG.ddbd330ef4eaff32b23645fb98551b81.JPG

L'époque moderne (post-vintage).

 

Le président de Vixen à propos de la modification de la série des orthoscopiques, uniquement le 4mm reste fabriqué suivant la formule Abbe.

 

Abbe Ortho's Unchiku Astronomical Telescope Parts and Astronomical Goods Store Scope Town

 

Excerpt from "Tweet of the Elderly" by former president Akira Saito of Vixen Optics Co., Ltd.

 

Abbe Ortho's Prank

Réussites et difficultés de l'ortho Abbe

 

The mainstream eyepieces these days are dominated by American size 31.7 size, and the 24.5 size Zeiss type seems to be declining.

However, among them, only the 4mm Abbe Ortho shows its outstanding strength, and its power has not diminished in response to the harsh eyes of all enthusiasts.

Then, what kind of eyepiece is Abbe Ortho is described in a technical book as follows.

 

"To measure angular distances within the field of view of a telescope, you need an eyepiece that has particularly little image distortion. For example, an orthoscopic eyepiece is that, and orthoscopic means image alignment and no distortion. In order to do so, the image shaping condition must be satisfied. However, in reality, there is an example of naming it orthoscopic even if there is about 30% distortion around the field of view .

 

Generally, what is called an orthoscopic eyepiece has a structure as shown in the figure, which is E. It was invented by Abbe in 1893. The usual design is that the field of view lens is BK7-F3-BK7, and the eye lens is a plano-convex lens of BK7, but there are also glass lenses that are different from this. With this glass combination, the eye clearance is about 78% of the focal length, and the apparent field of view is

inside and outside 45 °.

 

The orthoscopic eyepiece is one of the best eyepieces and can be used with short focal length reflectors such as F6 and F8. It is suitable for high-magnification observation and measurement because it has relatively little distortion, good achromaticity, and little surface reflection.

I don't make many low-magnification lenses because the lenses are thick and troublesome. (Telescope Optics Shotaro Yoshida Seibundo Shinkosha S53 Edition)

 

There are various types of orthoscopic, such as the Abbe type, the Prozel type, and the achromatic Ramsden type, which are sold by taking advantage of their respective characteristics, but the origin of the Ortho is still the Abbe type.

Even with Vixen eyepieces, Abbe type production is limited to this 24.5 4mm eyepiece and the graduated OR-12.5 reticle 31.7 eyepiece, especially for 4mm eyepieces only when custom-made.

 

Abbe Ortho is quite awkward when it comes to actual production. The biggest problem comes from the structure of three-lens bonding, and first of all, the accuracy of curvature polishing becomes extremely troublesome. This is because if there is a curve error that causes a gap on the laminated surface, it will not fit in the specified lambda. Also, when joining three lenses, the yield is poor due to the high craftsmanship required, so mass production is not possible.

The design is completely unsuitable for mass sales. Each one is literally a handmade product.

 

The 4mm is 24.5 size, so unlike the LV type, there are strict restrictions on the selling price, which is also a weak point.

 

Why don't you re-examine the Abbe Ortho made by the world's best Japanese, keeping the design values of the German genius firmly from 100 years ago ?

 

Q. How do you judge the quality of a lens at the manufacturing site?

 

First, inspect whether it is polished to the same curve as the design value. The inspection is performed by applying the [original] that has been polished to a predetermined curve in advance, but the original that is made of a concave lens is used for the convex lens, and the original of the convex lens is used for the concave lens. The prototype is always made with zero error, so it is very expensive.

 

When the lens and the prototype are overlapped, usually several interference fringes appear on the overlapped mating surface, and the fringes appear as a pale rainbow-colored ring. Interference fringes are also known as "Newton's rings", and the quality of the lens is determined by the number of lenses, about 3 depending on the object, the position where the ring can be seen, and whether the ring is a perfect circle. .. A distorted ring will not pass.

 

When the curve is almost perfect, the ring disappears and the whole lens is slightly yellowish, so-called "one color" is the best lens.

 

One color is evidence of complete polishing when the combination lenses are separated, such as the objective lens of an astronomical telescope, but one color is used for the above-mentioned three-piece laminated Abbe ortho lens. Color is not always considered the best. It is due to the following reasons.

 

When laminating uneven lenses, pre-match one or two Newton's rings outward so that the bonding agent (Canada balsam, resin adhesive, etc.) flows out from the mating surface of the lens at the time of bonding. It is intentionally polished to open the surface.

On the contrary, if the gap between the mating surfaces increases toward the center, the bonding agent will not flow out, and therefore the bubbles (air) accumulated inside will not easily escape and bonding will not be possible.

(In this industry, it is usually disliked as "middle plow" and fails the inspection, and in the opposite case, it is called "coro eyes" and it is OK because the air is well released.)

 

Then, what if the unevenness is perfect, at first glance it seems that a matching lens of excellent quality can be made, but I never see it at the production site.

 

The reason is as follows.

 

If the unevenness is adjusted to the surface, the lenses will momentarily stick to each other and will not come off. This is a terrifying phenomenon called "air bonding", and in this case, we have no choice but to throw away high-quality lenses.

 

Since the expansion differs depending on the material of both lenses, it may come off if it is soaked in hot water for a while, and I have tried it several times, but I have never succeeded. That's why one-color lenses aren't always considered good lenses in production. It's awkward to handle. Especially in the case of a three-lens lens, the risk ratio is higher, so it is usually avoided unless it is too late.

 

In short, is the polishing craftsman the secret of "rolling eyes"? Whether or not you have mastered.

 

Next is the bonding, but when the lenses are bonded unevenly, the lenses must be bonded accurately so that the optical axes of both lenses match. It seems that there is no problem if the centering work performed after polishing is done properly, but that is not always the case. For that purpose, usually, a centering microscope or the like is used to perform joining while centering.

In the case of a three-lens lens, it is not possible to join three lenses at a time, so first perform only two lenses, and then add another lens to finish the optical axis with three lenses. I heard that this work also had a lot of trouble at the stage of pasting the third piece because I used to use only Canada balsam that melts when heated.

Currently, it is easier to use a resin-based bonding agent that does not melt even when heat is applied after bonding (although that alone cannot afford to fail).

--- In any case, it is only a few millimeters in diameter like the OR-4 lens, and it is very difficult to use it as the optical axis of a three-lens laminated lens, so few people have this technology at present. It is.

 

It is a masterpiece to finish the lens polishing to "roll eyes" within the range of several Newton's rings. It's not easy.

In addition, master craftsmanship is required for joining. Both are difficult.

 

With all that hard work, Abbe Ortho is still alive and well in the astronomical world, because Ernst Abbe's design was so outstanding, and at the same time, the Japanese people's commitment to "manufacturing" was extremely strong. Can be said.

 

Je vous laisse lire et traduire au besoin.

Une petite vidéo : un doublet.

 

Un triplet :

 

Edited by lyl
  • Like 1
  • Love 1

Share this post


Link to post
Share on other sites

Bonjour 

 

Cela semble être un ancêtre de des or Zeiss 24.5.

Équipait la lunette Asiola premiere version, la noir, pas tout jeune donc.

 

Étonnamment, le coulant est 23.2, il est tres léger.

Je n'ai pas trouvé sur internet d'infos sur ces oculaires, on les vois bien équipant la première Asiola dans la recherche, mais aucune info sur les oculaires en question.

 

Des idée sur ca conception optique ? 

 

PSX_20240714_234020.jpg

PSX_20240714_234009.jpg

PSX_20240714_233956.jpg

PSX_20240714_233937.jpg

PSX_20240714_233923.jpg

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now