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JimK
Skygazer
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Reged: 09/18/05

Loc: Albuquerque, NM USA
Re: A Scope for the Ages or Just Aging? new [Re: Michael Edelman]
      #3798218 - 05/10/10 10:36 PM

Yes, a small, portable, excellent optics package has many merits.

And WELCOME TO CLOUDYNIGHTS!


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Johndob
professor emeritus
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Reged: 12/22/08

Loc: Gardena,Ca
Re: A Scope for the Ages or Just Aging? new [Re: JimK]
      #3798420 - 05/11/10 12:48 AM

Questar is a good Moon and Planetary scope but sometimes you need more aperture and faster optics to get to the faint stuff. There are astro photos on the Q website that demonstrate the 3.5" optics with a Starlight Express MX-916. I think i will look up any ETX 90 astro photos to see how inferior the images appear.

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GR1973
super member


Reged: 09/29/07

Re: A Scope for the Ages or Just Aging? new [Re: Johndob]
      #3798554 - 05/11/10 03:25 AM

I compared many astro-videos on youtube.com with what i get with my Q ....many times Q out perform a larger apreture on the moon and planets....

About Faint fuzzies you need to live in a dark place to search for it...Not only a big apreture and fast scope....But if you live in a big city with a massive light pollution you need an exteremly portable scope to carry and a long f ratio to increase the background darkness...and the only available choices are planetary system,moon ,sun and bright deep sky objects.Questar outperform many scopes in these condition this was not the case 50 years ago....With increasing civilization and more pollution questar will be more usefull.....A SCOPE FOR AGES
The only missing is goto but what is tge usefulness and what is the aquired skills i get from my hobby if i push a button to see a celestial object??? i can do this with a remote telescope or seeing hubble scope images on the internet


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Mark Rosengarten
member


Reged: 04/05/10

Loc: NY, USA
Re: A Scope for the Ages or Just Aging? new [Re: GR1973]
      #3798601 - 05/11/10 04:54 AM

As much as I enjoy seeing images taken by other people, for me, nothing beats capturing the photons with my own eyes. For some reason, a gorgeous photo cannot compete with an actual look-see, where my eyes capture the actual photons emitted long ago by the celestial object. That said, I don't get much joy out of locating faint fuzzies...to my eye, they all look more or less the same. I love planetary and solar observing. For that, the Questar is a gem of a scope! I could happily get rid of all my other scopes and just have the Q to keep me company.

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Erik Bakker
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Reged: 08/10/06

Loc: The Netherlands, Europe
Re: A Scope for the Ages or Just Aging? new [Re: Mark Rosengarten]
      #3798625 - 05/11/10 06:12 AM Attachment (54 downloads)

Quote:

For some reason, a gorgeous photo cannot compete with an actual look-see, where my eyes capture the actual photons emitted long ago by the celestial object.




That is why I enjoy the comfort of the Q and the amount of photons collected by my Q7. It works wonders on solars sytem AND deep sky (globulars!)

Clear skies,

Erik


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Rat8bug
Carpal Tunnel
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Reged: 01/07/05

Loc: Michigan
Re: A Scope for the Ages or Just Aging? new [Re: Erik Bakker]
      #3798692 - 05/11/10 08:14 AM

IMO, all this discussion is poppycock. One has to go back to the root of the why of Questar. The designer of the Q, indicated it was for "A lover of fine instruments". You have to break down what "fine" means. I look upon it as the Total package; including pleasing to the eye. Next is the Q was not designed to be a one dimensional tool. The Q3.5 ads showed photos of the moon, birds, landscapes, planets, squirrels, et. al. Galileo upset the world with less than an inch aperture. David Levy (a Questar owner) has many comets to his credit. Purpose and Persistance paves the way.

http://www.barrie-tao.com/questar1.html

Ciao....Barry

Edited by Rat8bug (05/11/10 08:16 AM)


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Clive Gibbons
Mostly Harmless
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Reged: 05/26/05

Loc: Oort Cloud
Re: A Scope for the Ages or Just Aging? new [Re: Michael Edelman]
      #3798756 - 05/11/10 08:53 AM

Quote:

I've had four Questar 3.5s- two standards (one of which I still own), a duplex, and a field model. Every so often I'd think I needed more aperture, sell the Q, and buy a big scope- a 7" refractor on a big Losmondy mount, a 10" GEM newt, and even a 17" Coulter. And every time I'd get tired of hauling all that iron and glass around, and the long setup time. I'd sell it all and get another Q. There's nothing else that gives you a super high quality observatory in a tiny, portable package. (BTW, I once bought an early ETX as a less expensive scope for travel, but it was so mechanically and optically inferior to the Q that I dumped it soon after.)

I do have a second scope- but it's even smaller: A 67mm Pronto I use for travel. I'm thinking of replacing it with a TV60 ;-)




Good thoughts, Mike.

And, welcome to Cloudy Nights!


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Les
scholastic sledgehammer
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Reged: 04/22/06

Loc: Maryland
Re: A Scope for the Ages or Just Aging? new [Re: Rat8bug]
      #3799315 - 05/11/10 02:06 PM

Quote:

David Levy (a Questar owner) has many comets to his credit




Barry,

Are you suggesting that David discovered those comets with his Questar?


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Rat8bug
Carpal Tunnel
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Reged: 01/07/05

Loc: Michigan
Re: A Scope for the Ages or Just Aging? new [Re: Les]
      #3799390 - 05/11/10 02:44 PM

I didn't say that....Barry


Quote:

Quote:

David Levy (a Questar owner) has many comets to his credit




Barry,

Are you suggesting that David discovered those comets with his Questar?




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akman1955
Post Laureate
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Reged: 09/07/09

Loc: Alaska, USA
Re: A Scope for the Ages or Just Aging? new [Re: Rat8bug]
      #3814016 - 05/18/10 11:22 PM Attachment (61 downloads)

I feel sorry for brian L on his questar having bad coating. Glad i have a good 1978 bb coated questar. Bought site unseen and lucked out i guess.Hope it stays good here in dry climate of fairbanks. Also by the way Frank I have lots of people everyday(i work on military base) wanting too buy my novas and chevelles regardless of your opinion. a coworker just bought back his 1969 "396" ss nova for $25,000 plus. So not bad investment in my eyes. As a professional mechanic I really like the simplicity and they now can be made better then back in the day.Plus They have styling and just look plain COOL.Why are they remaking all the old body styles?? Just ask Jay Leno..if it makes ME happy i'am Happy.I really like my Questar .john Oop's sorry clive didn't mean too be off topic and drege up other thread but owning stuff is personal to each individual. I don't understand people who argue or bash other peoples parade or happyness. noth said, john

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Clive Gibbons
Mostly Harmless
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Reged: 05/26/05

Loc: Oort Cloud
Re: A Scope for the Ages or Just Aging? new [Re: akman1955]
      #3814103 - 05/18/10 11:56 PM

No problem, John.

A few months ago, I saw a nice used BB Questar of '71 vintage at a local dealer. The primary mirror looked perfect.
It's last service was in 1978.
If I didn't already own a Q, I woulda bought it.

I kinda think the Questar that Brian bought had a defective overcoating. These things happen and since the underlying reflective material was silver, a porous overcoat would be trouble. The coating contractor (and/or Questar) is off the hook, since the failure happened a few years after the warranty expired.
If economic times were better, a more agreeable resolution to the problem might have been reached.
It's unfortunate that such is not the case...


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Brian L
professor emeritus
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Reged: 11/17/08

Loc: The garden paradise of Pittsbu...
Re: A Scope for the Ages or Just Aging? new [Re: Clive Gibbons]
      #3814905 - 05/19/10 11:16 AM

Jim's explanation is that moisture for this unusual phenomenon is that moisture can get in behind the overcoating and separate it from the BB coatings. As a physicist, I am having a hard time conceiving how this is possible without oxidizing the silver somewhere. If the topcoating were porous, I would think the inevitable result would be formation of silver oxide. Not so in this case.

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Brian L
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Reged: 11/17/08

Loc: The garden paradise of Pittsbu...
Re: A Scope for the Ages or Just Aging? new [Re: Brian L]
      #3814944 - 05/19/10 11:31 AM

I spoke to Cumberland also, and as an aside they have nothing to do with the broadband coatings. They only provide Questar with AlSiO coatings.

Edited by Brian L (05/19/10 11:41 AM)


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GR1973
super member


Reged: 09/29/07

Re: A Scope for the Ages or Just Aging? new [Re: Brian L]
      #3815098 - 05/19/10 12:31 PM

Quote:

I spoke to Cumberland also, and as an aside they have nothing to do with the broadband coatings. They only provide Questar with AlSiO coatings.



When i bought my new Questar three years ago,I changed my order from ALO2 to BB coating Just before shipping


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astro_que
sage
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Reged: 11/11/09

Re: A Scope for the Ages or Just Aging? new [Re: Brian L]
      #3815196 - 05/19/10 01:10 PM

Quote:

Jim's explanation is that moisture for this unusual phenomenon is that moisture can get in behind the overcoating and separate it from the BB coatings. As a physicist, I am having a hard time conceiving how this is possible without oxidizing the silver somewhere. If the topcoating were porous, I would think the inevitable result would be formation of silver oxide. Not so in this case.




Brian,
Coatings have become increasingly complex. Particularly with silver, there is such a variety of processes, it is impossible to say anything with certainty. Denton offered a coating called FS99, which had conflicting reports on durability; lasted well, yet one coating was destroyed by fog in a day. More recently, Lawrence Livermore developed a silver coating, described as "encapsulated silver", that is as durable as dielectric. The process is so complicated that I have been quoted $4K for a single prepped 12 inch mirror. Between these, it is reasonable to assume there are many varieties. We know that formerly, Questar used a coating of thorium fluoride, which, while not as protective as modern coatings, has lasted over 35 years in many specimens.

One possible mechanism for what you saw is that the dielectric layer provides some protection, on the order of what thorium fluoride provides. As pinholes in the silicon dioxide layer are all too common, then infiltration of moisture through these holes could cause separation.

I am curious as to the frequency of occurence of these pinholes. Perhaps they are more common than the actual damage you saw. In discussions with Optical Guidance Systems and one of their subcontractors, I received conflicting opinions on whether a mirror should be periodically cleaned. OGS advocated; the coating lab said no. With the exception of the Lawrence Livermore process, silver coatings are fragile. In the hands of the careful user, they provide siginficant benefit: smoother surface, less scattered light, and higher reflectivity.

Since many of us here have BB scopes that were owned by nontechnical people, and have survived many years (34 and 29 years in my examples), I tend towards the notion that an unfortunate set of circumstances resulted in what you saw. There were pinholes, but these are probably more common than the damage. The second factor is either some element of treatment by the prior owner that provoked this, or, in fact, a defective coating.

I prefer to leave this question open, because we simply do not know. Yes, the Midwest is drier than most coastal areas. But that does not exclude owner abuse, which could have taken several forms. Regardless of the locale, many basements are humid. Mine was, so I installed dehumidifiers, but they don't make it dry. Accidental introduction of a small quantity of liquid water through the eyepiece holder would also create a very high moisture condition in the tube. For these reasons, I advocate that everyone proactively keep the inside of the tube dry with a dessicant plug. This will also remove moisture of accidental nature.


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Brian L
professor emeritus
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Reged: 11/17/08

Loc: The garden paradise of Pittsbu...
Re: A Scope for the Ages or Just Aging? new [Re: astro_que]
      #3815237 - 05/19/10 01:24 PM

It's easy to speculate that Questar has some magical formula for coatings that is superior to all others. It's also easy to say hogwash and chalk it up to Questar mysticism. The reality is likely somewhere in between. It's not as complicated a process as they would like you to think, but it is also more involved than what you get with Meade UHTC and Celestron XLT coatings.

There's more to this story than I am willing to publicly disclose at this point. Who knows....someday I might write a CN expose piece.


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astro_que
sage
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Reged: 11/11/09

Re: A Scope for the Ages or Just Aging? new [Re: Brian L]
      #3815325 - 05/19/10 01:56 PM

Quote:

It's easy to speculate that Questar has some magical formula for coatings that is superior to all others.




Brian, I made no such speculation about magical coatings. As far as I know, they do not use the Lawrence Livermore encapsulated process. I provided information about the wide variety of coatings that exist. Questar made no statement to me about the complexity of the process. Questar doesn't coat; they send out to a lab


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Clive Gibbons
Mostly Harmless
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Reged: 05/26/05

Loc: Oort Cloud
Re: A Scope for the Ages or Just Aging? new [Re: astro_que]
      #3815390 - 05/19/10 02:27 PM

Robert,

didn't you mention Perkin-Elmer as being the coater for your older BB Questar?
At least, that's what Jim R. said when he saw your scope.


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astro_que
sage
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Reged: 11/11/09

Re: A Scope for the Ages or Just Aging? new [Re: Clive Gibbons]
      #3815452 - 05/19/10 02:56 PM

Clive, actually, it was the newer Questar, the '81, that Jim identified as having a Perkin-Elmer coat. Interestingly, the '76 seems to have less reflection intensity off the corrector. The '81 has a strong violet reflection, while the '76 has a subdued shade of green as one would expect with a modern optic. One may surmise that they switched for a reason. Durability?

I've been looking at local coatings companies. I have a call into one for general information. There are two companies local to Questar and me, though I have no idea whether they use them. I have seen two reflectivities attributed to Questar BB mirrors. One is extremely high: 99.9%. Such a coating is offered by ECI here in Willow Grove: http://www.evaporatedcoatings.com/mirror/print/109.htm
Another coating, more compliant with what Jim told me in a recent conversation, is offered by Acton, a division of Princeton Instruments, the makers of the CCD cameras: http://www.princetoninstruments.com/Uploads/Princeton/Documents/Datasheets/Princeton_Instruments_Acton_Optics_Protected_Silver_Coating_Rev%20A1.pdf.

Back in the days of yore, an amateur astronomer silvered his mirror in the bathroom with silver nitrate. The main danger was that of explosion of the concentrated nitrate. The coating might last six months. Today, it is a much more complex process. There are binder layers, there is the silver, there is the tuned dielectric overcoat, and there is the protective layer.

Today, pure dielectric coatings, made of 40 or more alternating layers of two or more materials with different indices of refraction, are advocated for durability. Opticians refer to each layer as an "etalon", the French word for gauge. Each alternating layer achieves total internal reflection for a specific band of wavelength. However, because these coatings are so thick, they actually change the figure of the mirror. Also, Jim explained to me that all their scopes both commercial and military, are optically identical. There is a strong need in government for high IR reflectivity. Dielectric coatings cannot be tuned to function over a sufficiently wide bandwidth.

The dielectric enhanced silvered mirror consists of binder layers, the silver layer, which may be encapsulated, and several etalons made of different materials for enhancement. These days, this ensemble is overcoated with silicon dioxide. The advancement in the past ten years has been extraoardinary. Perhaps some day, the Lawrence Livermore process will become feasible for small mirrors. It is simply too labor intensive at present.


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Clive Gibbons
Mostly Harmless
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Reged: 05/26/05

Loc: Oort Cloud
Re: A Scope for the Ages or Just Aging? new [Re: astro_que]
      #3815509 - 05/19/10 03:34 PM

Seems that at this point, we don't know who does the BB coating for Questar.
We don't know the exact configuration of the coating.

We do know that it's warranted for 5 years and that applies to the original owner.
Many folks who own BB coated Q's report great longevity.
Some folks haven't been as fortunate.

Not much else to say, re. coatings, IMO.

Over 'n' out.


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