STF Mirage 7" - need help from brothers from Russia.

[alinoe]

Hello,

I'm Marcin from Poland. I have very big problem with my STF Mirage Maksutov-Cassagrain 7" (180/1800mm), which I bought about 2 years ago (2003 year of production). All the time, which I used it I have had suspicions, that something is wrong, because I had strange flares on single frames, which I made. I decided to open optics, clean it and check, if something could create these flares. When I detached meniscus I found, that secondary mirror has lot of scratches on it. I didn't know, if these scratches were on aluminium layer or on mirror. I send it to company, which aluminizes mirros to aluminize it. They told me, that these scratches were on aluminium layer, which they removed but there is another, adhesive layer under aluminium, which they cannot remove. They suspected, that this layer can contain some chromium molecules (or not?) . They tried to remove it with Hydrochloric acid or Aqua regia but with no success.

Meanwhile I contacted with @Fidel here from this forum, who was an optical specialist in STF. He told me, that he'll check if he has some secondary mirror somewhere or if he doesn't have, he will mechanicaly remove layer, figurize and polish again if I'll send him secondary mirror or whole telescope.
I decided to go to Brest in Belarus and send him the telescope, but the contact was gone

So I have big asking for you: Does anyone have (for example) broken STF Mirage 7" and can send me secondary mirror? Or is here anyone, who is able to mechanically remove layer from secondary mirror and polish it again with keeping curvature of spherical convex side? Of course I'll pay for everything

I send a picture, how the mirror looks like before and after aluminizing.

Sorry for my English, but my Russian language is much worse...

[alinoe]

This is a mirror after aluminizing. It's still bad-looking.

[leviathan]

Hi Marcin,

I doubt anybody here will have a secondary for this not so popular model of the telescope. But even if they do, due to the known problems now in the world I don't think that they will be able to send it to you from Russia.

If I would be you, I would find some optics lab in EU (Germany, etc.) and ask them to polish the secondary for you. Considering the small size of the secondary I don't think that it's going to be expensive.

[alinoe]

Hello,

I contacted with B&M Optik before and OptoSigma in France. The answer was no, because they will not change their machine settings for one glass. And probably each company will answer the same . As it comes to political issues, as I wrote before, I'm so despairing, that I can even go to 400km from my home - Brest in Belarus, send the glass/telescope and receive it back from Belarus. I think you can send item to Belarus with no problem.

[alinoe]

The one thing, which would help me a lot, would be a "R" - radius of circle, on which is convex side done. The mirror is, I guess, spherical. If anyone knows, what should be a radius?

[rigel14]

Я  бы мог помочь ,только с зеркалом больше ничего не надо делать, скорее всего подслой под алюминием действительно хром и снять его всегда проблема,но можно.

[alinoe]

Ok, but how can you help? Please keep in mind, that after treatment of acids the surface of mirror can have little damages. UK-Orion optics, which I sent to diagnoze and aluminize wrote: "The etching they have caused is imbedded into the glass surface and can not be removed chemically at all." , so only repolishing I guess is the only method

[rigel14]

Надо взглянуть поближе, говорить можно всё что угодно. Я занимаюсь покрытиями и видел много чудес.
Переполировка это крайний вариант, но и это можно сделать ,а потом сделать хорошее покрытие с защитой.

[Fidel]

Почему пропал? Всё время на связи. Полежал в больнице чуток. Теперь вот снова дома.

Я же Вам объяснял - там многослойка. Требует перешлифовки.

Запасные вторички для 7" STF у меня есть в обилии (в оправах с блендами). Найду - дам знать. Пока не искал - со временем очень туго. Дел много, сил мало. Потерпите. Найду.