School USSR refractors. The path of “perfection”

The author of the article is Alexey Petsyk, an astronomy lover from Moscow.
The material was published on the website star-hunter.ru at the personal request of the author of the article.
All rights to text and illustrations belong to Alexey Petsyk.
The author of the translation into English is Ruslan Ilnitsky
Translator’s note is in italics.

Perfect is the worst enemy of Good Enough!

But if we pick up … a telescope and look at the sky
with an assisted sight, we will see two stars,
three stars, four stars …
Best of all, of course, five stars!


Chapter 1

Small school refractor

Small School Refractor (MShR) RTM-60 - modifications

Small School Refractor (MShR) RTM-60 – modifications

After completing work on the history of the School meniscus telescopes of the USSR, somehow it turned out by itself that I was interested in school refractors of which in the USSR, as everyone knows, 2 types were produced – Large Small school refractor (Bol’shoy Shkol’nyy Refraktor  – BShR) and Small School Refractor (Malyy Shkol’nyy Refraktor – MShR).
It would seem that there is not much to collect here – well, there are two – but this turned out to be true only at first glance. Having dealt with the topic more closely, I found out that the MShR was produced in at least 6 modifications (and the BShR – probably more, until I counted seven), and the development did not go as expected “from simple to complex”, but for some reason the other way around, with what something with an increasing degree of simplification. This article is devoted to the description of the history of the release and “improvement” of the MShR.
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SVBONY SV171 Zoom Eyepiece 8mm-24mm review

I received an SVBONY SV171 Zoom Eyepiece 8mm-24mm (SKU: W9131A). for testing. The zoom eyepiece is very convenient for quickly selecting the optimal magnification, or for cases when you need to quickly change the magnification without having to change eyepieces. The focal length in the zoom eyepiece is changed by rotating the body. Along with the focal length, the angular field of view of the eyepiece also changes.

Declared characteristics:

Focal Length  8-24 mm
Eye Relief 18-19.5 mm
Apparent Field of View 38°-56°
Barrel Size 1.25″
Lens Structure  7-Elements/4-Groups
Filter Threads Standard 1.25″(M28.5 x 0.6)
Coatings Fully Multi-Coated
Blackened Lens Edges Yes
Barrel Safety Recess Yes
Eyecups Twist-Up, metal

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SVBONY SV152 20mm SWA Illuminated eyepiece review

SVBONY SV152 20mm SWA Illuminated eyepiece

SVBONY SV152 20mm SWA Illuminated eyepiece

I received an SV152 20mm 70 Degree SWA Illuminated Eyepiece (SKU: W9115A) for testing.
The manufacturer positions this eyepiece for the following applications:
-setting the exact alignment of the telescope and finder
-polar alignment (by drift method)
an invaluable aid to centering guide stars and astrophotography target objects
-the perfect eyepiece for alignment of computerized GoTo systems

Declared characteristics:
Field of view 70 degrees
Focal length 20 mm
Eye relief 16 мм
Crosshair – laser engraved
Lens group – 4 Group / 5PCS
Power – 2PCS 1.5V (AG5)
Lens Coated – FMC .
Field Stop – 25 mm
Thread – M28.5*0.6
Net Weight – 221g/ 7.8oz
Dimension – 75*53*102 mm

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