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tal 200K Mirror Cleaning.


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I need to clean the mirror on my beloved Tal 200K. I have been putting it off for some time, but it needs to be done.

What is the safest method of cleaning the mirror / meniscus lens.

Also, will I need to collimate after assembly.

Your suggestions would be greatly received.

Steve L

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Andy's collimation thread here: http://stargazerslounge.com/discussions-scopes-whole-setups/153878-klevtsov-collimation-how-i-go-about.html

There is a link in Yahoo Tal groups showing how Bill Brady cleaned his primary on the 200K.

This was a in the old Tal group that was hosted here. I don't think these threads have made there way back to the main forum yet?

*EDIT* Here: http://tech.groups.yahoo.com/group/TALScopes/files/FAQs/EZ%20200K%20Primary%20Cleaning/

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Leave the primary in the rear cell.

Mark the rear cell/backplate in relation to the the tube and unscrew the 6 bolts/screws that hold it to the tube. Don't touch the collimation/alignment bolts/screws. The back of the scope should come off with a slight tug.

Clean the primary as you would any other mirror. Good news is, whatever type of coating Tal use, it's very rugged and tough.

The miniscus can now easily be got at. Again, just treat it as a lens. Take care, if you use cleaning fluid, use sparingly, as you don't want any excess to get between the elements. Again the coatings on the meniscus is as tough as Russian Special Forces boots. I just use a lens cloth to clean mine. Don't forget to blow off any nasty hard particles first.

Line up the backplate to the marked tube and pop it back on.

You probably won't have lost collimation/alignment.

Easy peasy lemon squeezy.

:)

Andy

ps: I'm nearly finished doing some work on Stuart's(Rossco72) 200K. I'll be quite sad when it's time for the beast to go back to him ;)

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Another thing.............

The backplate and back of the ota, are machined to tight tolerances, so the chance of the mis-alignment of the optics are close to zero, unless you put the backplate on the wrong way.

Andy.

edit

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If you want to clean the miniscus without taking the backplate off......

You can, unless you've weightlifter forearms, fit you hand through the curved veins.

Give it a blow with a puffer bulb, then with a cleaning cloth, gently wipe.

You could have another hand in with a small mirror, so you can see what you're doing. You may get strange looks from your wife/girlfriend when you ask for a loan of their makeup mirror though. Be warned !!

:)

Andy.

edit: if you see a particle that doesn't blow off, try using a cotton bud to carefully remove it. Better safe than sorry.

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I'm such a sado.

But, to be honest, if it wasn't for my love of the mechanical side of Astronomy, I may have given the hobby up, to some extent, so bad the weather's been.

Been having great fun. Would love a production line of 200K's to tinker with.......

If anyone want's me to tinker with their's, I'm more than happy. Kathleen(SpookyKat) ain't no slouch at 200K tinkering too ;)

:)

Andy.

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Andy's advice is spot on how I do it, pop the back off and you

can easily clean the primary or secondary. Likewise

I just use a rocket blower to clean the secondary by reaching

through from the front.

The 200K is a great scope for this, accessing the mirrors etc

by popping off the back makes for an easy life. I flocked mine

by just popping off the back and putting some felt in. :)

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Thanks all for your great comments. It's glad to hear from the members of the old Tal group. As this weekend is going to be foul weathered, I may have a go. i will let you know of my progress.

Make sure there is a picture update. While I no longer have a 200K I'm still interested in the reputation that grew around the scope of one that is better left to the professionals. It would be nice to see that myth put to rest.

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Steve -

If I remeber correctly you have one of the rarer(to these shores) and newer F8.5 200K's ?

If so, then I third the 'lots of pics' shout, if you decide to do it.

I'd love confirmed that the tube is thick rolled steel rather than the older style aluminium and pics of how the backplate attaches the tube. In the aluminium version, both the tube and backplate are machined to suit. I've wondered how they go about it on the steel tube(if it is). Heavy ring welded to the tube and machined??

As a side note, but as possibly Klevtsov owners may be reading this thread, I'd like to ask a question regarding your secondaries? I've been working on Stuarts 2002 model and have noticed the lack of strong purple anti-reflection coatings, as seen on my 2001 version. It should be noticable in the daylight whilst looking down the focuser(especially around the edge). Was wondering about everyone elses. Ta in advance.

Cheers,

Andy.

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Very interesting thread. Good to hear that there are lots of 200K owners around. I was beginning to think I was one of only a few.

Fortunately my 200K has a clean mirror. After a 130 mile car ride to collect, it gave textbook diffraction rings, and still did last time I checked.

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I tried and failed to get my Primary off. It was very stiff when I took out the 6 bolts and I really didn't want to bash it to get it off....

Andy, If you feel like giving the TAL a good clean while you have it then fire away...

Cheers

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Stuart - Your primary looked quite clean actually. There are a couple of small marks, which I'll have a look at, but mine has a couple, that aren't removable and it doesn't comprimise the views. I'll give it quick 'once over', when I give it the final star test tweak, when it's next clear. I was foiled last night as I just needed an extra half hour, to finish. Pah.

I drove down from Paisley to just north of Birmingham to get mine off of Daz. Thankfully and kindly, he came north of Birmingham to meet me at the big services there(name escapes me). I remember chuckling, as I left the car park for the long journey home, regarding the hand over of the weapons grade Tal 200K crate, wondering if all the CCTV cameras were pointed our way. Nowadays, I may have been whisked away by some goverment agency....;)

As for Tal mirrors, my 200K is 10 years old and apart from a few marks, the actual aluminising is in terrific nick, for an open tube. In fact I've got even older Tal newts that have been well used, but the mirrors are in great shape. I guess Tal's parent company and their involvement in military optics may have something to do with the coatings ? No idea, just something I've wondered over the years, as I've had other scopes whose mirrors haven't come close to lasting as well. :)

:headbang:

Andy.

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I checked my secondary, for a purple coating, on Sunday. I noticed when viewing with a fine beamed torch, the mirror was fogged. I hoped against all hope it was not

inside the meniscus lens. I then cleaned thew face of the lens and re-checked.

To my relief there staring back at me was a lens of polished pristine glass. I could not guarantee seeing a purple coated lens though?

Tested the Tal last night on Jupiter, Moon, Vega double/doubles and can say they were very sharp indeed.

That's been the trouble all along. I will clean the primary, but at present, I don't think I have to.

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Well done :)

How did you clean the lens?

Using a compact mirror as AndyH suggested?

I checked my secondary, for a purple coating, on Sunday. I noticed when viewing with a fine beamed torch, the mirror was fogged. I hoped against all hope it was not

inside the meniscus lens. I then cleaned thew face of the lens and re-checked.

To my relief there staring back at me was a lens of polished pristine glass. I could not guarantee seeing a purple coated lens though?

Tested the Tal last night on Jupiter, Moon, Vega double/doubles and can say they were very sharp indeed.

That's been the trouble all along. I will clean the primary, but at present, I don't think I have to.

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Good to hear that your cleaning resulted in a better image.

To be honest Steve, I half expected your more modern Tal not to have the deep purple coating. Tal moved on to a different coating type later.

I've had to clean my secondary miniscus twice since I've had mine, yet never needed to touch the primary. You would have expected it to be the other way around !

I'm not a cleanliness freak when it comes to mirrors, although when it comes to lenses(be it eyepieces, 200K, refractors), I like to keep them tidy.

Andy.

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Cleaning the lens:

A one handed operation was better for me. Working blind I cleaned my lens by blowing any dust etc with a large bulb blower and then softly brushed the lens.

Using a piece of pure cotton wool slightly dampened with Isopropyl alcohol, wiped the lens. Finally ,very softly polished with a micro cloth.

Andy,

Checked the Tal 200K Tube with a magnet. It's made of aluminium. I was near as damit certain because of the weight.

cheers

Steve

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