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#926 clamchip

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Posted 31 July 2020 - 07:43 PM

I found a note in this Cave catalog:

https://wiki.telesco...60s_Catalog.pdf

page 6 Astrola 6 Richest Field Telescope.

"coming geophysical year 1957-58" would that make the catalog 1956?

Which catalog is the Red catalog? 

 

Robert


Edited by clamchip, 31 July 2020 - 07:45 PM.

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#927 KentTolley

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Posted 31 July 2020 - 10:32 PM

Drawings in the Red catalog by Alika Herring are dated 1957`so it must be at least 1957. Last page of text in Red catalog, referring to the back cover with its 8" Deluxe scope, Cave says "for more than four years the 8" Astrola Deluxe has been an exceedingly popular telescope. If, as you say, Red catalog is from 1956 that would mean the 8" Astrola deluxe was around since 1952. But Cave only opened his doors in 1953. And his earliest scopes were mounted on Telescopics mounts without Seal-Master bearings in the RA axis

Please see the first sentence in my initial argument.
All the prices in the Red catalog are slightly higher than those in the May 1959 Sky and Telescope ad. YOu can find the May 1959 ad on Cave-Astrola.com documents page. Thus it is fair to conclude Red catalog came after May 1959. The write-up on the RFT with its reference to the Geopysical year is probably unmodified from a catalog prior to the Red catalog as are some of the scope photographs.


Edited by KentTolley, 01 August 2020 - 02:32 AM.

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#928 RichA

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Posted 01 August 2020 - 02:10 AM

Here's a great post on Oil Flat Autocollimation:

https://www.cloudyni...llimation-test/

I'm leaning towards this test for my Cave 10 inch DK cass.

You can use this test for any telescope, without the expensive

optical flat, especially expensive in larger diameters.

 

Robert

Could use mercury too, if you have enough of it. 



#929 tim53

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Posted 01 August 2020 - 10:54 AM

Could use mercury too, if you have enough of it. 

But don't breathe while using it.



#930 DAVIDG

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Posted 01 August 2020 - 11:18 AM

But don't breathe while using it.

 One  issues with using an oil flat is when the optics are not coated ie your figuring a newtonian mirror  bare glass reflects about 2% of the light and and you get that off the oil surface as well plus the light is reflected off the mirror two times.  So the result is very dim image that is difficult to see with a typical light source. The  reflective surface of Mercury would work better but the stuff is toxic, expensive and if you spill any you just turned the area into super fund toxic  site. This is only problem when testing uncoated reflective optics. Finished telescope there is no problem using oil since you have plenty of light.

    There is simple solution to the light problem with using non toxic cooking oil,  which is an ultra bright LEDs. You can now get them that are so bright you need a welder's  mask to look at them and only for few dollars. So you now plenty of light to use a non toxic oil to do the test. 

 

            - Dave 



#931 Bomber Bob

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Posted 02 August 2020 - 11:01 AM

Old Clock Drives & Tracking

 

Last night I observed Jupiter for over an hour with the C102 on the 1980s Mizar Super Polaris EQ, and I only had to make occasional DEC axis adjustments.  Some folks have asked about the tracking accuracy of these vintage mechanical drives, so here's what I've learned:

 

- Make the axes SMOOTH.  So many of these Japan-made mounts have that pine-sap based grease, and after 50+ years it gets sticky.  If you can, remove that gunk & re-grease; otherwise, you're putting more load on the drive, and the tracking will be unreliable at high powers.

 

- Use BALANCE to help the drive.  Once the manual motions are smooth, I use weight & balance on the East / West sides:

--- Scope is lagging behind the object, then favor the West Side.  Easy when the counterweight(s) are already on this side.

--- Scope is getting ahead of the object, then favor the East Side.  Happens once in a while with my Meade StarFinder EQs.  Seems crazy to shift the weight towards the OTA, but it works.

 

Of course, you still have to polar align & level the mount.  And, if the drive system has serious issues with Periodic Error, slippages in the drive train, etc. my tips won't fix those.  IF your clock drive is battery-powered... keep SPARE BATTERIES on hand.  All my EQ mounts with drives are very quiet.  Yes, they have status lights, but some will stay on when battery is about to snuff it.  Nearly lost my mind one night (back when I first started imaging) and the StarFinder stopped in the middle of a video capture!  Trudge into the house, and find only 3 new AAs -- and I needed 6...

 

Like Ol' BB, Uncle Rod is a Bama Boy, and I enjoy reading him for his style as much as his content.  Here's his article on Clock Drives from about 7 years ago:   http://uncle-rods.bl...tock-clock.html


Edited by Bomber Bob, 02 August 2020 - 11:02 AM.

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#932 Kasmos

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Posted 02 August 2020 - 03:56 PM

I'm a little surprised that the Mizar SP mount is big enough for the C102 since it seems smaller duty then a Vixen SP. That said, I like mine so far and it will proably become my first choice for any of my 60s that I want to put in EQ mode. My one complaint, the tripod legs are a bit on the small/thin side and should have been made longer. 


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#933 clamchip

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Posted 03 August 2020 - 06:54 PM

Some great information on German Equatorial Mounts:

http://www.alpo-astr...h/Equ_Mount.pdf

 

Robert


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#934 DAVIDG

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Posted 03 August 2020 - 07:10 PM

- Use BALANCE to help the drive.  Once the manual motions are smooth, I use weight & balance on the East / West sides:

--- Scope is lagging behind the object, then favor the West Side.  Easy when the counterweight(s) are already on this side.

--- Scope is getting ahead of the object, then favor the East Side.  Happens once in a while with my Meade StarFinder EQs.  Seems crazy to shift the weight towards the OTA, but it works.

 

 What causes this is that the worm is not correctly messed with the main drive gear. So either one side of the worm or the other is in contacted with the teeth of the main drive gear depending how it  is gravity loaded.  Take the cover off the drive and rock the scope back and forth. The worm shouldn't move and neither shouldn't the teeth of the main worm  in the worm. 

 

              - Dave 


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#935 KentTolley

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Posted 03 August 2020 - 07:43 PM

Some great information on German Equatorial Mounts:

http://www.alpo-astr...h/Equ_Mount.pdf

 

Robert

This is amazing.  Thank you so much for this.



#936 Bomber Bob

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Posted 04 August 2020 - 09:49 AM

I'm a little surprised that the Mizar SP mount is big enough for the C102 since it seems smaller duty then a Vixen SP. That said, I like mine so far and it will proably become my first choice for any of my 60s that I want to put in EQ mode. My one complaint, the tripod legs are a bit on the small/thin side and should have been made longer. 

Yes, the wood tripod is too short.  But the mount has no problem with the C102, or my Dakin 4 -- which is about twice the Celestron's weight.  It's almost too short for my 6336 (76x1200), except that the 2 finders push the balance point skywards for comfortable eyepiece height.  A 60mm - 130mm with 900mm or shorter focal length should be fine.  Shoot!  My Mizar AR-1 on the ShortPod has no trouble carrying my RV-6 -- just need to find a motor drive kit for it.



#937 Vesper818

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Posted 04 August 2020 - 10:30 AM

You sure you don't mean "just before sunrise"? Venus is a morning star now and is well up before dawn and therefore setting well before sunset.


Therefore daytime viewing before sundown makes perfect sense. 🙂
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#938 Terra Nova

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Posted 04 August 2020 - 01:34 PM

Therefore daytime viewing before sundown makes perfect sense.

Touche’ I read the comment out of context and missed that part.


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