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Optical quality of meade mirrors that mounted on the Starfinder 16 "in the years 2001

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#1 pastorgalactico

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Posted 08 February 2018 - 05:04 PM

Hello;
I have been offered a mirror of 16 "F4,5 PIREX of the year 2001 that was mounted on the reflectors Starfinder 16" of meade and I would like to know the owners of those mirrors or telescopes that give me information of the optical quality of those mirrors that are then manufactured (2001) in the USA.

I would also like to know the thickness of these mirrors because I do not know it very clearly if they are 50mm thick or 45mm thick.
Regards;

J.Tapioles



#2 photoracer18

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Posted 08 February 2018 - 05:31 PM

Might be more than 2" thick. The old mirror makers used to use a 6:1 diameter to thickness ratio. Not sure if Meade did in the Dobs. However I have a 16" Meade mirror from about that era at home that is out of one of the white tube Starfinders. Its going into an old NightSky kit that was made for these mirrors if I ever get around to finishing it.



#3 pastorgalactico

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Posted 08 February 2018 - 05:48 PM

Hello;
Well, the first data I do not like for my project because the cell and the axes of height in my project are designed for one that is 45mm thick and 13.5 kg in weight.



#4 lifesagrape

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Posted 08 February 2018 - 05:50 PM

If manufactured at the Meade (USA) facility, it would be Pyrex glass and 1.625" thick (approximate). The Pyrex glass would have been from U.L. or  Newport Glass Works and are a bargain at what they can be purchased for on the used market.


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#5 J A VOLK

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Posted 08 February 2018 - 06:08 PM

I had a 16" Starfinder Dob - the mirror was quite good for the price point, probably 1/4 wave. I know they varied - can't really generalize in this era - best if someone can check the individual mirror or you take your chances.
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#6 Jon Isaacs

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Posted 08 February 2018 - 06:25 PM

If manufactured at the Meade (USA) facility, it would be Pyrex glass and 1.625" thick (approximate). The Pyrex glass would have been from U.L. or  Newport Glass Works and are a bargain at what they can be purchased for on the used market.

 

I had a 16" Starfinder Dob - the mirror was quite good for the price point, probably 1/4 wave. I know they varied - can't really generalize in this era - best if someone can check the individual mirror or you take your chances.

 

The mirror in my 16 inch is a Starfinder Dob mirror from sometime back then.  It's slightly over 1.5 inches thick.  1.625 inches would be about right. 41mm.  a 10:1 thickness ratio.

 

I have heard the 16 inch starfinders were more variable in quality than the smaller ones.  I thought mine was quite decent, I had Mike Spooner refigure it.  He said it was a decent mirror but the one he done previously was not.  

 

Jon


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#7 Tucker512

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Posted 08 February 2018 - 07:00 PM

I can't find it now, so this is somewhat anecdotal, but I distinctly remember reading a review of a 16" Starfinder years ago that was used for astrophotography and it stuck in my mind because it was the first time I had seen someone describe a mirror as "1 wave."  Having now tested and refigured some older mirrors (though not a Meade, FWIW), I can believe that.  I can't personally speak to the quality of the Meades, but that description always stuck out in my mind.  I think with any older mirror it would be worth testing it first because it seems like there was a lot of variety in quality generally.

 

Scott



#8 Richard Whalen

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Posted 08 February 2018 - 07:08 PM

If you want top quality I would figure in cost of a re-figure and coating. Otherwise I would pass. The 3 I have looked through from that era were from almost fair (around 1/3 wave) to terrible (1 wave). Nothing OWL cant fix.


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#9 pastorgalactico

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Posted 08 February 2018 - 07:19 PM

Hello;
The translations of google are not usually very precise and for that reason I have understood that in these mirrors there was great variety on the optical quality of some over others.
So you could get a good mirror and other not so good.
The mirror that they offer me can not be tested by me, so I will need more information from other users of these mirrors to clear up doubts.
My first option was to buy a mirror of 16 "GSO and seeing this mirror of meade at a good price has made me think if it would be worth it, being a mirror of meade of the USA and Pyrex and that's why I'm asking about the quality general of those mirrors.
Regards;

J.Tapioles



#10 Pinbout

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Posted 08 February 2018 - 07:22 PM

https://www.cloudyni...lescope-mirror/

 

I've seen several of meade mirrors refigured by Jerry Wilkinson from Galaxy, he signed them as JL or JC, could never get why is wasn't JW. but it is and its better than 1/8~ very close to 1/10~, very good for a 16" mirror


Edited by Pinbout, 09 February 2018 - 12:05 PM.

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#11 ccaissie

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Posted 08 February 2018 - 07:45 PM

2 of our club scopes are 16" f/4.5 Starfinders.  One is in our dome on an eq mount, the other on its dob base.  Neither mirror was very good, almost 1 wave overcorrected in the dome scope, and the dob has a really bad zonal issue. (pic)

 

They are nice blanks, flat on the back, no astigmatism, and a good edge.  

 

I refigured the dome scope back in 2002 to about 1/5 wave when we recoated it.  At a second recoat in 2015, I touched it up to about 1/10 wave and it's superb now.  The dob mirror is waiting for a refiguring...

 

When we haul the dob to an event...like on Cadillac Mt.,  we swap the dome mirror into the dob. At some point, we'll have 2 good mirrors.

 

 

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  • cameradump 2017 099.JPG

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#12 CHASLX200

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Posted 09 February 2018 - 06:19 AM

They were hit and miss.  No Zambuto or Lockwood, but many were pretty good.



#13 pastorgalactico

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Posted 09 February 2018 - 06:25 AM

The mirror in question is this, if someone can identify it in case it has been reconfigured again;

s-l1600.jpgs-l1600_1.jpg



#14 pastorgalactico

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Posted 09 February 2018 - 06:37 AM

Hello;
It is the same mirror that is for sale in this forum.



#15 pstarr

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Posted 09 February 2018 - 09:07 AM

2 of our club scopes are 16" f/4.5 Starfinders.  One is in our dome on an eq mount, the other on its dob base.  Neither mirror was very good, almost 1 wave overcorrected in the dome scope, and the dob has a really bad zonal issue. (pic)

 

They are nice blanks, flat on the back, no astigmatism, and a good edge.  

 

I refigured the dome scope back in 2002 to about 1/5 wave when we recoated it.  At a second recoat in 2015, I touched it up to about 1/10 wave and it's superb now.  The dob mirror is waiting for a refiguring...

 

When we haul the dob to an event...like on Cadillac Mt.,  we swap the dome mirror into the dob. At some point, we'll have 2 good mirrors.

Looks like a pair of lifting handles.



#16 Pinbout

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Posted 09 February 2018 - 10:27 AM

The mirror in question is this, if someone can identify it in case it has been reconfigured again;

s-l1600.jpgs-l1600_1.jpg

yes, that's the guy Im talking about. just by that signature I know its a very nice mirror. he refigured a lot of Meade mirrors back then. so yes it was refigured and is not stock, and should sell for a lot more than $850


Edited by Pinbout, 09 February 2018 - 10:29 AM.

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#17 pastorgalactico

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Posted 09 February 2018 - 01:03 PM

Hello;
Then according to you that optics is good.
One could venture to say what would be the quality of the optics more or less.

Regards;
J.Tapioles



#18 Alvin Huey

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Posted 09 February 2018 - 04:06 PM

My old Meade mirror made back in about 1993 or 94 was about 1 5/8" thick and has a really nice figure.  It was tested and found to be better than 1/8th wave.  I don't remember the numbers of the test results, but it was 1/8th wave and Strehl was about 0.95.  Fine mirror.  When others looked through it and asked if it was a Pegasus or Galaxy or some other premium maker.  I get that many times.  I had (actually still have) my 22" Pegasus mirrored telescope with me at the same time.

 

BTW, many of you may already know.  Carl Zambuto was John Hall's protege (sp?) when Carl started making mirrors.  

 

It was rebuilt into a truss in 96 and rebuilt to a lighter truss in 00.  When I rebuilt it the first time, I tossed everything including the 4" secondary and bought a 3.1" secondary.  Only thing that remained was the primary.  Sold it in 03 to my friend from TAC.  He still has it and it makes a regular appearance at GSSP and CalStar.

 

I think I just lucky with that one.

 

You can see it on my website.


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#19 pstarr

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Posted 09 February 2018 - 07:40 PM

 

 

BTW, many of you may already know.  Carl Zambuto was John Hall's protege (sp?) when Carl started making mirrors.  

 

 

That's not true and was addressed by Carl once on his mirror group web site. Carl said he never met Hall face to face. They corresponded by email and by phone about the aspects of the the business end of mirror making. Hall never showed him how to make mirrors.


"I never met him in person. I know that sounds unusual, but he was in Texas and I’ve been in Washington State these last 18 years."

 

"So to set the record straight, John Hall did not teach me how to make mirrors. I was already a mirror maker of eight years before we met, but only by hand. I call John my “commercial mentor” because he prompted me to move forward into machine-based production, then he opened the door for me to get into the business, by following behind him with small mirrors as he went on to larger. The instruction he gave me for figuring mirrors was very simple. It was something like, “Start with a 60% diameter lap, go back and forth and use offsets, then go to 50% diameter, and so forth”. That and the short sequence contained in the shop video were what I worked with. It was nothing like what we did when we taught our method here on this forum over a period of years. John did however stand by and continue to coach and give me moral support until I found my magic formula, and that might be the greater part of his contribution to my work and career. What he did for me overall was invaluable, because prior to meeting him the idea of making mirrors for a living was not in the realm of possibility, in my mind. I preciously had no inkling of how it could be done.

We stayed in contact for twenty or so years, right up until his last days in the hospital. We talked on the phone, we wrote back and forth. We talked about everything under the Sun, not just mirror making. He was a good friend, and we had mutual respect for each other. And he never made any issue of what I became. He was only proud to be my friend, and in the later years I had the opportunity to turn the tables and help him many times with things he needed as he wound down his career.

Thanks, John. I will always remember you and honor you for your contribution to all of us, but especially to me.

As John would say,

“Cheers”

Carl Zambuto"


Edited by pstarr, 09 February 2018 - 07:41 PM.

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#20 pastorgalactico

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Posted 10 February 2018 - 02:40 PM

Hello;

To clear doubts.
Asin is the signature on the mirrors reconfigured by Jerry Wilkinson.
It is mechanically engraved on the glass surface of the back of the white space as seen in the foreground. Nothing more.

Regards;

J.Tapioles

 

IMG_7160.jpgIMG_7163.jpg



#21 NGC704

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Posted 10 February 2018 - 02:52 PM

Yep, that's my 13.1" f/4.5 mirror, presumably a refigured Coulter. It is one of two Wilkinson mirrors I have personally handled, and both were similarly signed by Jerry.



#22 pastorgalactico

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Posted 10 February 2018 - 02:56 PM

Hello;

Thanks for the confirmation Kurt Maurer.

Regards;

J.Tapioles



#23 Pinbout

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Posted 10 February 2018 - 03:54 PM

Ah ...the c is his middle inital

 

just because that is signed like that. Doesn’t mean that’s the only way he signed them

 

especially when refiguring Meade mirror


Edited by Pinbout, 10 February 2018 - 03:55 PM.


#24 Pinbout

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Posted 10 February 2018 - 03:59 PM

It’s really funny how this thread is about Meade mirrors turns into is it or isn’t it a Jerry Wilkinson refigured mirror. fingertap.gif



#25 Pinbout

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Posted 10 February 2018 - 04:12 PM

Btw you can’t sigh with sharpies on polished back side.

 

ive tested several J.C. Sharpie signed mirrors, just like the link I posted earlier, and seen others here for sale as jerry’s Mirrors also.

 

the ones I’ve tested are very well corrected. Better than 1/8~ approaching 1/10~ 

 


Edited by Pinbout, 10 February 2018 - 04:17 PM.



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