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Sort of a Broadband Mystery in a Good Way

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#1 jmiller1001

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Posted 04 May 2021 - 10:14 AM

I bought a used Questar (F-1701-BB-FF-C) from a reputable seller here on CN and the other site.  According to my math (to be verified by Questar) the scope is circa 1974 or 1975 - and as you can tell from the S/N, the scope has Broadband coatings.  The coatings are in great shape and the star test (done a couple of times - I didn't believe it....) is excellent!  Not bad for a broadband coated scope that is 46-47 years old.  Although, I have to admit, that it's a bit of a mystery (in a good way) that the coating integrity has endured this long.....


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#2 RMay

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Posted 04 May 2021 - 01:04 PM

One guess might be that the scope simply went through a period of hibernation due to other things taking priority in the previous owner’s life. It happens... but good for you, certainly...

Ron

Edited by RMay, 04 May 2021 - 01:04 PM.

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#3 Terra Nova

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Posted 04 May 2021 - 01:39 PM

My 1985 Q-Standard Broad Band’s coatings look like new.


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#4 Erik Bakker

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Posted 04 May 2021 - 01:54 PM

Quite a few BB live long and happy.

 

As a side note, all reflective coatings gradually loose efficiency over time.

Thankfully, they are well protected inside the Questar, enhancing their lifetime significantly.


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#5 Opie Taylor

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Posted 04 May 2021 - 02:04 PM

(For myself, and probably a few others - ) 

OK, so, how do you inspect the coatings on these guys? 

Exactly what am I looking for?  Any vids out there addressing this?

I am hoping and thinking mine has been in "hibernation" too....    


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#6 Spikey131

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Posted 04 May 2021 - 02:31 PM

(For myself, and probably a few others - ) 

OK, so, how do you inspect the coatings on these guys? 

Exactly what am I looking for?  Any vids out there addressing this?

I am hoping and thinking mine has been in "hibernation" too....    

Read this:  https://www.cloudyni...e-for-purchase/



#7 Erik Bakker

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Posted 04 May 2021 - 02:32 PM

Deterioration of reflectivity is easiest to see with a new Questar side by side.

 

Degradation of the mirrorcoatings appears as brown rusty spots, generally starting around the outer edges of the primary mirror and easily visible to the naked eye upon close inspection.



#8 vrotondi

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Posted 04 May 2021 - 07:35 PM

(For myself, and probably a few others - ) 

OK, so, how do you inspect the coatings on these guys? 

Exactly what am I looking for?  Any vids out there addressing this?

I am hoping and thinking mine has been in "hibernation" too....    

Hello Opie:

Since I am the one that sold it to you, the original owner, the person that I bought it from said he kept it stored away in a closet and never took it out. He just didn't have time to use it. Hope that helps.



#9 Opie Taylor

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Posted 04 May 2021 - 09:09 PM

Thanks, Spikey -

Here is what Ben wrote about the coatings:  - 

Optics coatings inspection.  With a bright flashlight, inspect the corrector lens and main mirror.  The corrector will show some dust and smudges under the intense light, but should have no haze or white texture.  Look for problems at the edge, and little snowflake like spots anywhere.  You will be able to tell whether issues are on the front surface or inside.  Don’t worry about a knuckle smudge and use a bulb blower to blow away dust.  The main mirror should be bright and free of any yellowing or bright white or silvery effects.  Inspect the very outer and inner edges especially carefully - even the thinnest line of silver-white at the edge can indicate the start of a problem.   

(And I now remember reading this, it just didn't "stick"....).   

 

Thanks, Erik -

I don't have a new one to compare to, but your comments sound good, for sure. 

 

Thanks, Vito -

Yup, it does help.  I knew from his ad comments that he did not use it much (hence, my interest).  But, from what I can tell, he was at least the 2nd owner.  The original "acceptance" letter from New Hope was addressed to someone else (in NY).  This example does seem to be mint in every way, (so happy and thankful for that!), but I have only seen one other to compare it to (and it's an old one too).  

  

Again, thanks All! - 

Manny Doughty



#10 Wisconsin Steve

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Posted 05 May 2021 - 07:14 PM

Very nice! Enjoy


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#11 jmiller1001

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Posted 26 May 2021 - 07:30 PM

By the way, I sent my scope back to Questar for a standard service.  Jim R. told me that the BB coatings had just started to degrade and that the scope had lost 9% reflectivity from new - which is still pretty incredible.  And a 9% loss is imperceptible.


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