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Cave Mirror Registry

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#851 rolo

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Posted 18 October 2018 - 07:05 PM

I disagree on that one. Do the same with a classic car and the value plummets. In any case I’m sure it’s better than original. That’s what really matters.



#852 tim53

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Posted 19 October 2018 - 11:41 AM

On the other hand, is a cave mirror that is original to the scope but not signed as valuable as a signed mirror?



#853 Mikefp

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Posted 19 October 2018 - 11:54 AM

I disagree on that one. Do the same with a classic car and the value plummets. In any case I’m sure it’s better than original. That’s what really matters.



Rolo,
Lots of opinions on this topic but hopefully each owner uses good judgment for best level of restore. I agree for a classic cars that is in great running condition and is all original . However, if the classic car motor is seized or severely out of tolerance a reputable restorer may re-machine the block and replace hopefully with original parts that are oversized to fit the re-machining, increasing the value.

Somewhat different analog is that Cave scopes were sold with many levels of mirror quality. There are great (eg.Herring) Cave mirrors and not so great Cave mirrors. Refiguring a substandard mirror can bring the scope back into use. Worst yet keeps the Cave from being parted out or trashed. Lots of Caves on the market but very few with Herring mirrors that demand top $$. Mirror Registry is a great tool to keep track of all mirrors and dates.

Edited by Mikefp, 19 October 2018 - 12:12 PM.

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#854 L. Regira

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Posted 19 October 2018 - 01:50 PM

When I ordered my Cave in 1978 I thought it would be the ultimate scope that would last a lifetime with no need for another.  I used it for many years and it did a great job at low power where my astigmatism limited the view more than the mirror.  Eventually  I noticed it was not doing much better on the planets than my RV 6 and in 2002 as it was due for a recoat I decided to send it to Steve Swayze for testing. He found the mirror was very poorly made and he was amazed that I had been pleased with the views. Once returned from Spectrum Coatings after a Swayze refigure a whole new world was open to me as I saw subtle ovals on Jupiter,  the Encke Division on Saturn's rings, etc.  I would have loved to have had that mirror a killer straight from the Cave plant but  it was not to be and since it was my lifetime scope I am glad it was refigured.  It still has the Cave pedigree but with the caveat that it has a Swayze refigure. It wound up being what I expected from a Cave but did not get due to the dying days of Cave Optical.  

Lawrence 


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#855 Geo31

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Posted 19 October 2018 - 02:04 PM

I dunno.  I think I'm in Rolo's camp.  

 

With the Gustavson Cave, if the mirror is disappointing, I'll likely make (or buy) a new mirror and preserve the original.  That's a little extreme, but the scope, while not exactly rare is certainly uncommon.



#856 CHASLX200

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Posted 19 October 2018 - 03:26 PM

I dunno.  I think I'm in Rolo's camp.  

 

With the Gustavson Cave, if the mirror is disappointing, I'll likely make (or buy) a new mirror and preserve the original.  That's a little extreme, but the scope, while not exactly rare is certainly uncommon.

But you give me a hard time on my Caves.



#857 CHASLX200

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Posted 19 October 2018 - 03:28 PM

When I ordered my Cave in 1978 I thought it would be the ultimate scope that would last a lifetime with no need for another.  I used it for many years and it did a great job at low power where my astigmatism limited the view more than the mirror.  Eventually  I noticed it was not doing much better on the planets than my RV 6 and in 2002 as it was due for a recoat I decided to send it to Steve Swayze for testing. He found the mirror was very poorly made and he was amazed that I had been pleased with the views. Once returned from Spectrum Coatings after a Swayze refigure a whole new world was open to me as I saw subtle ovals on Jupiter,  the Encke Division on Saturn's rings, etc.  I would have loved to have had that mirror a killer straight from the Cave plant but  it was not to be and since it was my lifetime scope I am glad it was refigured.  It still has the Cave pedigree but with the caveat that it has a Swayze refigure. It wound up being what I expected from a Cave but did not get due to the dying days of Cave Optical.  

Lawrence 

Cave went downhill in the later 70's like Unitron did. They rushed out whatever they could near the end, after 1977 i would say.

 

The mounts are just junk in my book, and that is from all the makers in the 60's and 70's. 



#858 Geo31

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Posted 19 October 2018 - 03:50 PM

But you give me a hard time on my Caves.

What's  your point?  Mine is that I'd keep the original mirror and make another to use.  Keeps all the original stuff together instead of erasing the original work.



#859 L. Regira

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Posted 19 October 2018 - 04:01 PM

I have to confess that when I sent my mirror to Swayze to check it out I was not expecting it to come out of testing poor.  He tested it and found it to be overcorrected throughout except for the edge which was noticeably undercorrected.  He said it would almost be impossible to achieve a good focus.  He had just completed another 12.5 inch mirror and the lap was ready and used to refigure mine.  I did not have the option to save the dog and buy a new mirror as he went to work on it immediately which I am grateful.  Although my mirror and scope are Caves it is now the best Swayze-Cave it can be.


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#860 Geo31

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Posted 19 October 2018 - 04:51 PM

I have to confess that when I sent my mirror to Swayze to check it out I was not expecting it to come out of testing poor.  He tested it and found it to be overcorrected throughout except for the edge which was noticeably undercorrected.  He said it would almost be impossible to achieve a good focus.  He had just completed another 12.5 inch mirror and the lap was ready and used to refigure mine.  I did not have the option to save the dog and buy a new mirror as he went to work on it immediately which I am grateful.  Although my mirror and scope are Caves it is now the best Swayze-Cave it can be.

 

Just want to be clear, I'm not throwing stones either.  I'm not a collector really, I'm a "user."  The Gustavson Cave is really special, or I would just have it refigured (if it needed it).  The Field Cave I was planning on refiguring if necessary.  I'm just saying I agreed with Rolo that it's now a Swayze mirror, and clearly nothing to be ashamed of, right?  :grin:

 

I don't know if Jon is keeping track of refiguring in the registry, but I would think that would be a good idea (but that's just my $0.02).


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#861 rolo

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Posted 19 October 2018 - 05:04 PM

Cave went downhill in the later 70's like Unitron did. They rushed out whatever they could near the end, after 1977 i would say.

 

The mounts are just junk in my book, and that is from all the makers in the 60's and 70's. 

Yea you would say and have said that many time. My 12.5 f/6 was a 1976 and it was excellent. Beautiful star test with nice smooth figure and phenomenal planetary views. My friends 1977 10” was another fine mirror as well.

The mounts are junk? Only you can find a Edmund mount with plastic bushings no bearings and pipe fittings superiorlol.gif. I just can’t take you serious chief.



#862 John Higbee

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Posted 19 October 2018 - 05:08 PM

My 1979 mirror has red rouge on the edge.

I haven't tried to remove it, the mirror doesn't need cleaning yet so I just left it alone for now.

How many of you have red rouge on your mirror's edge?

I was noticing my new 1959 Edmund Super Space Conqueror also has red rouge on the edge. 

I did some reading and the red rouge is slower than cerium oxide and leaves a finer polish

but will stain everything it touches so maybe that explains why it wasn't cleaned off. 

Robert

 

attachicon.gif post-50896-0-92682500-1481761829_thumb.jpg

I do.  John

 

cave M793839 mirror engraving.jpg



#863 clamchip

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Posted 19 October 2018 - 05:29 PM

I'm not sure if I mentioned it but my 1979 mirror with the rouge on the edge is

a phenomenal performing telescope, a absolutely fantastic OTA.

The tube inside is a coarse chop fiberglass that is a total light trap and very

high contrast even during daytime terrestrial observing. A excellent Japanese

focuser, excellent diagonal support, a really really nice scope.

I think I remember reading Cave still had some pretty talented opticians there

at the end. 

He must have in 1971 too because my 6 inch Student Deluxe has the finest 

mirror I've ever owned.

 

Robert


Edited by clamchip, 19 October 2018 - 05:34 PM.

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#864 CHASLX200

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Posted 19 October 2018 - 05:40 PM

What's  your point?  Mine is that I'd keep the original mirror and make another to use.  Keeps all the original stuff together instead of erasing the original work.

I did keep the factory mirror.  I don't know of one Cave that i changed the mirror in and i have had 4 Caves.  I think you are sore over the 2..5" mount i had. And that was changed before i bought it.   Only thing i did was nip the shaft off as it would bump the pier leg at my low laitude dude.  That shaft was not normal from the get go and it caused the dec balance problem.

 

As for the Cave i just got nothing on it is the same as well. New tube spider, mirror cell and a refigured mirror that was all done before i bought it.  So i never made any changes to any Cave other than that 8" Cave when i dropped the factory focuser and had no choice but buy a low profile focuser.

 

Only change i am going to do on the green Cave mount i have now is it will no longer have a drive, and redoing the latitude adjuster so it works right and adding a lock down bolt to the RA axis.  I would like a mount that works smooth as silk at 400x and up.  Plus the drive can go back on the mount at any time.

 

The mount is not worth a hoot if the latitude adjuster is not holding and the mount flexes like a yo yo when touched.


Edited by CHASLX200, 19 October 2018 - 05:42 PM.


#865 CHASLX200

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Posted 19 October 2018 - 05:45 PM

Yea you would say and have said that many time. My 12.5 f/6 was a 1976 and it was excellent. Beautiful star test with nice smooth figure and phenomenal planetary views. My friends 1977 10” was another fine mirror as well.

The mounts are junk? Only you can find a Edmund mount with plastic bushings no bearings and pipe fittings superiorlol.gif. I just can’t take you serious chief.

I heard other wise on that mirror. But then i never used it myself so can't say. It could have been the best or just so so, but i will never know.  My Cave mount and Star liner mount have plastic  bushings as did my Meade RG mount.  It is the clutch that hangs up at high power when trying to center a planet. Try to nudge the scope it goes too far this or that way when trying to center. 

 

That Edmund had no drive or clutch to hang up when trying to center a object at high power..  I don't know of any pipe fittings on my 1.5" Edmund in the mount itself. Once my Cave mount is rebuilt to my specs it should be smooth at silk and will be a leave outside mount.  Only thing that i would call a pipe fitting and it really was not was the polar cap that screwed into the pier dear.  Best mount ever , case closed.


Edited by CHASLX200, 19 October 2018 - 05:51 PM.


#866 John Higbee

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Posted 19 October 2018 - 09:06 PM

I'm not sure if I mentioned it but my 1979 mirror with the rouge on the edge is

a phenomenal performing telescope, a absolutely fantastic OTA.

The tube inside is a coarse chop fiberglass that is a total light trap and very

high contrast even during daytime terrestrial observing. A excellent Japanese

focuser, excellent diagonal support, a really really nice scope.

I think I remember reading Cave still had some pretty talented opticians there

at the end. 

He must have in 1971 too because my 6 inch Student Deluxe has the finest 

mirror I've ever owned.

 

Robert

Robert - my 1979 mirror is also a great performer...which really gratified me, since I knew that Cave quality had tailed off towards the end of the 70's...recently took this picture of the Moon (with a Galaxy Smartphone)...the picture is good, but the visual in the eyepiece was even better!

 

moon 13 October (3).jpg

 

I had to correct several significant flaws when I got it (drive clutch was screwed up, and the secondary spider was sloppily installed), but from first light on, the images were superb (and got even better after I had the primary and secondary realuminized by Majestic!)

 

John


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#867 Geo31

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Posted 19 October 2018 - 10:38 PM

I did keep the factory mirror.  I don't know of one Cave that i changed the mirror in and i have had 4 Caves.  I think you are sore over the 2..5" mount i had. And that was changed before i bought it.   Only thing i did was nip the shaft off as it would bump the pier leg at my low laitude dude.  That shaft was not normal from the get go and it caused the dec balance problem.

 

As for the Cave i just got nothing on it is the same as well. New tube spider, mirror cell and a refigured mirror that was all done before i bought it.  So i never made any changes to any Cave other than that 8" Cave when i dropped the factory focuser and had no choice but buy a low profile focuser.

 

Only change i am going to do on the green Cave mount i have now is it will no longer have a drive, and redoing the latitude adjuster so it works right and adding a lock down bolt to the RA axis.  I would like a mount that works smooth as silk at 400x and up.  Plus the drive can go back on the mount at any time.

 

The mount is not worth a hoot if the latitude adjuster is not holding and the mount flexes like a yo yo when touched.

 

I'm sorry....  WHAT???



#868 PiSigma

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Posted 20 October 2018 - 11:35 AM

I don't know if Jon is keeping track of refiguring in the registry, but I would think that would be a good idea (but that's just my $0.02).

I have been putting an entry in the Notes field of the registry if I know of a mirror that has a modern refigure. But, so far, that has only been 3 mirrors and 2 of them are ones I had refigured.

 

I will say that I'm a stickler for originality. I have tried to keep my restorations as original as possible. If I do a modern modification, like a different focuser, I make sure it is reversible. Any other mods need to be period correct. I'm the same way with my car. It's just the way I am.

 

But....I don't have a problem refiguring a Cave mirror if it tests poorly. As noted, I've had 2 refigured myself. At the end of the day I think we all want these scopes to perform as best as possible and it doesn't make sense to me to suffer with a poor image from a poorly figured mirror if it can be corrected. While these are great classic reflectors they don't have the rarity or historical significance of say, a Clark, so I don't think their value, if that is important to someone, should be affected by having the mirror refigured by a qualified optician.

 

And I'm not sure I buy into this theory that earlier Caves are better than later ones using any date cutoff. Unless we have actual test results from almost every mirror in the registry we just can't make statements like this. What I can say is I have had a 1958 mirror that tested poorly, a 1970 mirror that tested poorly, a 1971 mirror that tested excellent as well as a 1974 mirror that also tested excellent. And I have read many posts in this forum from experienced owners of later models that say their mirrors are excellent. With all of the comments I have read over the years along with limited test results, I think the only statement that can be made about the quality of Cave mirrors is that there are good ones and bad ones all over the range of production and that testing is the only sure way to know what you've got.


Edited by PiSigma, 20 October 2018 - 11:38 AM.

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#869 Mikefp

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Posted 20 October 2018 - 11:46 AM

I'm not sure if I mentioned it but my 1979 mirror with the rouge on the edge is

a phenomenal performing telescope, a absolutely fantastic OTA.

The tube inside is a coarse chop fiberglass that is a total light trap and very

high contrast even during daytime terrestrial observing. A excellent Japanese

focuser, excellent diagonal support, a really really nice scope.

I think I remember reading Cave still had some pretty talented opticians there

at the end. 

He must have in 1971 too because my 6 inch Student Deluxe has the finest 

mirror I've ever owned.

 

Robert

I wish the optician who performed the figuring signed his or her name to the mirrors for documentation.  I also have great performing mirrors from the 1970's. My 8" f8.7 mirror  has a strehl ratio of .97 and performs excellent with original coating!

A good astronomy friend worked at the Cave shop during the late 1960's to early 1970's and has many stories.    He did lots of the coarse to medium mirror grinding.    I believe the mirrors were ultimately sent to a separate figuring room with a separate group of opticians..


Edited by Mikefp, 20 October 2018 - 11:54 AM.


#870 CHASLX200

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Posted 20 October 2018 - 02:46 PM

I have been putting an entry in the Notes field of the registry if I know of a mirror that has a modern refigure. But, so far, that has only been 3 mirrors and 2 of them are ones I had refigured.

 

I will say that I'm a stickler for originality. I have tried to keep my restorations as original as possible. If I do a modern modification, like a different focuser, I make sure it is reversible. Any other mods need to be period correct. I'm the same way with my car. It's just the way I am.

 

But....I don't have a problem refiguring a Cave mirror if it tests poorly. As noted, I've had 2 refigured myself. At the end of the day I think we all want these scopes to perform as best as possible and it doesn't make sense to me to suffer with a poor image from a poorly figured mirror if it can be corrected. While these are great classic reflectors they don't have the rarity or historical significance of say, a Clark, so I don't think their value, if that is important to someone, should be affected by having the mirror refigured by a qualified optician.

 

And I'm not sure I buy into this theory that earlier Caves are better than later ones using any date cutoff. Unless we have actual test results from almost every mirror in the registry we just can't make statements like this. What I can say is I have had a 1958 mirror that tested poorly, a 1970 mirror that tested poorly, a 1971 mirror that tested excellent as well as a 1974 mirror that also tested excellent. And I have read many posts in this forum from experienced owners of later models that say their mirrors are excellent. With all of the comments I have read over the years along with limited test results, I think the only statement that can be made about the quality of Cave mirrors is that there are good ones and bad ones all over the range of production and that testing is the only sure way to know what you've got.

They were  like SCT's, hit and miss.  No two mirrors will be the same.




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