Tell Me About Russian Mirror Lenses!

Started 3 months ago | Discussions
xaprb Forum Member • Posts: 92
Tell Me About Russian Mirror Lenses!

Hi! I’m a bit lost trying to research Russian mirror lenses and sort out their makers, brand names, focal lengths and apertures, history, and the like. I haven’t been able to find any comprehensive sources online for this topic. I’d love to have a website with a listing of all of them in one place, but that doesn’t seem to exist.

What do you know about them? Please reply and tell me!

For example: what’s MTO? What’s LZOS? What’s the difference or relationship, if any, between an MTO lens and a Rubinar? What’s a Tair mirror? What are the meanings of all the letter/number codes like “3M-6A” and what are common misspellings, given that there are Cyrillic characters involved (I’ve seen people freely interchange C and S)? Is there really an MTO 1000mm f/10 mirror lens, or is it mistakenly labeled and is really an MTO 1000mm f/11? Is there really an MTO 1000mm f/11 or are people mistyping the 1000mm f/10? (I’ve seen users write in some forum threads, “I have a Russian 1000mm f/11, it’s great” and then the same user elsewhere say “I have a Russian 1000mm f/10, it’s great”)? Why is the MTO 1000A apparently an 1100mm focal length, that’s either a mistake or a really confusing choice of model/brand, isn’t it?

… I have so many questions, but I’ll stop there! Looking forward to learning lots from you

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gatorengineer Regular Member • Posts: 132
Re: Tell Me About Russian Mirror Lenses!
1

Niet - or no in Russian.  Dont do it.  Russian Mirrors are extremely heavy and sloppy mechanically.  Get yourself a nice Japanese mirror lens and be happy.  I have owned a few RUssians thinking  the optics would be a cut above.  Didnt work out that way

MOD Tom Caldwell Forum Pro • Posts: 43,188
Just a few words based on “Maksutov”

xaprb wrote:

Hi! I’m a bit lost trying to research Russian mirror lenses and sort out their makers, brand names, focal lengths and apertures, history, and the like. I haven’t been able to find any comprehensive sources online for this topic. I’d love to have a website with a listing of all of them in one place, but that doesn’t seem to exist.

What do you know about them? Please reply and tell me!

For example: what’s MTO? What’s LZOS? What’s the difference or relationship, if any, between an MTO lens and a Rubinar? What’s a Tair mirror? What are the meanings of all the letter/number codes like “3M-6A” and what are common misspellings, given that there are Cyrillic characters involved (I’ve seen people freely interchange C and S)? Is there really an MTO 1000mm f/10 mirror lens, or is it mistakenly labeled and is really an MTO 1000mm f/11? Is there really an MTO 1000mm f/11 or are people mistyping the 1000mm f/10? (I’ve seen users write in some forum threads, “I have a Russian 1000mm f/11, it’s great” and then the same user elsewhere say “I have a Russian 1000mm f/10, it’s great”)? Why is the MTO 1000A apparently an 1100mm focal length, that’s either a mistake or a really confusing choice of model/brand, isn’t it?

… I have so many questions, but I’ll stop there! Looking forward to learning lots from you

Far from an expert on Russian mirror lenses but I will comment on what I have picked up.

A certain Russian lens designer Dimiti Maksutov designed a variant of the mirror lens - the technical difference of which confuses me. But his design was good enough for his name to be associated with a distinct mirror lens type and this design is used for some (at least) high magnification astro-telescopes. After all the principle of mirror based telescopes and mirror lenses for photographic purposes is much the same as far as I know. Maksutov type astro-telescopes can be bought.

That said the MTO range of lenses has a reputation for being very large and very heavy - built like tanks (?) This sort of flies in the face of the idea of lightweight compact mirror lenses. But they are said to be good if you can stand the weightlifting …. (Guess: “M” is for “Maksutov” type design?)

From my resources there is the MTO 500/8.0 (1955-1966); MTO-500A 550/8.5 (in versions 1970-1985); the “MTO-35M?” 350/5.6 (About 1958) said to be 39mm screw mount, “half format” - never heard of it other than in a book; and the gigantic MTO-1000 1000/10 (in variations 1955-1970)

Somewhere along the way their lens designers must have gone back to the drawing board and I have an excitingly named “MC 3M-5CA” which is a modern build-lens of excellent construction 500/8.0. As light as a Japanese type but physically longer and narrower in shape - presumably this is because of its Maksutov design. In any case I have a number of mirror lenses and have to admit that this particular one is my favourite. Especially as it was obviously “new” and never used. “MC”would be “multi-coated”?

Its logo (a “C” inside a circle and triangle) tells me that it was made by LZOS and its serial number starting with “89” tells me that it was made in 1989.

LZOS stands for “Lutkarinskii Zavod Opticheskogo Stekla” and is a satellite company of KMZ (Zenit) based in the city of Lytkarino.

I also believe they made a range of mirror lenses known as “ZM-*A” (type 500/8.0, 500/6.3 “with magnesium bodies”) (1971-1985) and also the Rubinar mirror lenses. In fact LZOS might be the only Russian factory to make mirror lenses. (But I don’t know).

There apparently was a MTO-1000A 1100/10.5 (1970-1990) No idea what its build was.

I have eyed off the idea of a Rubinar but they have always been too expensive for my flights of fancy. I have not checked their prices recently but they are certainly not in fire sale. Presumably they are a good product.

I think the Rubinars were successors of the “ZM” type from 1989 and that my MC 3M-5CA seems to somehow fit somewhere in-between - maybe an early Rubinar?

Of course lenses all should have “names” and not just awkward numbers. “Jupiter” and “Rubinar” seem a lot more buyer-friendly than “MC 3M-5CA”

The Russian lens numbering system is indeed weird - don’t fight it ….

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Tom Caldwell

OP xaprb Forum Member • Posts: 92
Re: Just a few words based on “Maksutov”

Thanks Tom, this is very interesting information. Between this and some other reading I've been doing, I'm starting to fit the puzzle pieces together!

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Ching-Kuang Shene
Ching-Kuang Shene Veteran Member • Posts: 6,356
Re: Tell Me About Russian Mirror Lenses!
2

There are in general four typical designs for photographical mirror lenses:

  • Schmidt-Cassegrain aka SCT: This type is usually used in telescopes such as Celestron, Meads, etc. There is a disc protrusion from the front glass, which is aspherical and thin. Usually, there is no more correction lenses in the lens tube, and, as a result, edge image quality is not so good, expecting more coma than usual. But, this type of mirror lenses usually have long focal length such as 1000mm and 2000mm and are light. They use knobs at the rear end for very accurate focusing.

  • Maksutov Cassegrain aka MAK: This is a lens type invented by Dmitri Maksutov, a Russian during WW2.  The front glass is a thick concave one, and, the lens is rather heavy.  At the center of the rear surface of the front concave element is a circular spot, some in silver while some others maybe in black.  This is the secondary mirror.  Due to size, weight and design, a MAK rarely has a focal length beyond 1000mm.  Celestron and Meads both make MAK lenses, and most Russian mirror lenses are of this type or variation.  Quastar is the most well-known American lens maker of this type.  Questar 700 is a very good photographical mirror lens of 700mm.

  • At about the same time of the MAK, A. Bouwers in Netherlands employed a concentric corrector concept in his design.  This technique was used by both East and West Germany CZ to build super fast 500mm and 1000mm mirror lenses, namely: Mirotar 500mm 1:4.5, Mirotar 1000mm 1:5.6, Spiegelobjektiv 500mm 1:4 and Spiegelobjektiv 1000mm 1:5.6.   In the front, there are two symmetrically placed meniscus glass elements with the secondary mirror as a circular spot mounted on the inner meniscus element.  Here is a post of mine about the Spiegelobjektiv 1000mm 1:5.6.  This one has the Mirotar 500mm 1:4.5.  Some Japanese mirror lenses also combined this technique and Mangin mirrors to yield more compact systems.  As far as I know, the Pentax 1000mm 1:8 and Sigma 500mm 1:8 are good examples.  Sigma also made a 500mm 1:4 with the same idea.  Please see here .  Unfortunately, this lens has rather poor image quality as many early Sigma lenses do.

Carl Zeiss Mirotar 500mm 1:4.5

  • Mengin mirrors: Normally, in classical mirror lens designs the reflective surface faces the incoming ray directly, and, consequently, the incoming ray will not enter the mirror.  A Mengin mirror, on the other hand, has the reflective surface coated on the other side of the mirror.  As a result, an incoming ray enters the lens to reach the reflective surface, and then exits the lens, resulting in TWO refractions (i.e., enter and exit).  The advantage of this design can shorten the lens tube due to the reflections.  If the main mirror can use Mengin mirror design, the same idea can also be applied to the secondary mirror.  Most  Japanese mirror lenses use Mengin design, although some older ones may use a combination of two different designs.  For example, the corrector of the Pentax 1000mm 1:11 is a combination of the Bouwers design and Mention design, while the primary mirror employs a Mention design.

Mengin Mirror

Hope this helps.

CK

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Dr JLW Senior Member • Posts: 1,314
Re: Tell Me About Russian Mirror Lenses!

Just a bit if history.

Maksutov's invention was a form of compact telescope made with only spherical elements.  Previously these compact used apsherics as in Schmidt Cassagrain.  The downside is that tolerances on Maksutov designs are very demanding so good example like the Questar are very pricey.

Making aspheres of the desired shape for a true Cassagrian got cheaper when someone discovered that pulling a vacuum on the blank, grinding it spherical, and then releasing the vacuum produced the required shapes.  This lead to cheaper but high quality  true Schmidt Cassegrains like the Mead .

There is third type kind of Russian since it was designed and built to spy on the Russians, the "Solid Cat"  The are called solid and weigh like a solid piece of glass but have many glass elements inside.  These were rejected by the CIA because they are very heavy and were sold by Vivitar as Series 1 solid Cats at about 1/10 of what they cost to produce.  I learned about these from the man who designed them.

A note about Bauers designs.  They have all  concentric surfaces.  This eliminates spherical aberration so they need correction only for color and astigmatism.   They work very well once you take into account that the focus surface is also concentric, that is section of a sphere,

OP xaprb Forum Member • Posts: 92
Re: Tell Me About Russian Mirror Lenses!

Very interesting — thank you both!

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MOD Tom Caldwell Forum Pro • Posts: 43,188
Type comparison

CK - I presume that there were hybrid variations of the main types.

My “1980’s” Makinon 300/5.6 has conventional proportions and I believe it to be Schmidt Cassegrain but it has correction lenses behind the main mirror.

My Russian 1989 build MC 3M-5CA 500/8.0 is not a particularly heavy lens 594gm* (unlike the MTO type).  I don’t know its internal construction as it is in perfect condition so I am not about to mess around with it.  It also has correction lenses behind the main mirror but the object lens is concave. The secondary mirror is (also) silvered on the forward facing surface.    The secondary mirror seems to be attached to another lens situated behind the concave object lens. Its shape is also less conventional being quite visibly longer and narrower 127(L) x 74(D)**  I regard this as my best mirror lens (out of several that I own) it is obviously of a different build type.

I have a very cheap recent purchase conventional (SC?) construction Kelda that is not very good but an easy-grab for comparison: 500/6.3 669gm*  90(L) x 97(D)** Also has correction lenses behind the main mirror- which seems to be par for the course on all the mirror lenses.

* weighed without caps.

** barrel measurement only in mm.

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Tom Caldwell

FrancoD Forum Pro • Posts: 15,601
Re: Tell Me About Russian Mirror Lenses!
Dr JLW Senior Member • Posts: 1,314
Re: Tell Me About Russian Mirror Lenses!

The JIm Chung blog state that the Vivitar Series 1 "Solid Cat" has shown disappointing results.  As mentioned in teh blog the rear blank filter has to be i place to deal with the spherical aberration.

There is another  sadder reason and it can vary from sample to sample.  Perkin Elmer made tehse to Military Specification including the front surface.  This surface was very precise but looked ugly.  Ponder and Best told Perkin Elmer to shine them up to look good.  The Perkin Elmer people told them it would reduce performance.  Ponder & Best, Vivitar, told them these were to be bought by doctors and lawyers who wanted a shiny impressive surface and would not notice the lost performance.  I heard this from the man who designed the lens when we were working together on something else.

Mine is decent but my superzoom often gets better results.  I suspect that the few out that have Perkin Elmer markings on them will do a lot better.

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