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My new insane Cave project

Started by fct-150, 08/21/2014 02:11AM
Posted 08/21/2014 02:11AM Opening Post
I've been chasing 8-inch Caves for awhile, but I never expected this! 8-inch f/4.5; maybe 5. Definitely not an f/6.

The motor tracks like a champ and the everything is VERY nicely balanced and smooth. But the mount is not pretty. I see about 30 hours of work here. I may have the Meade 50 guider body and the 50 finder body sent off to be powder coated (just the white part of the tube body!). The fiberglass is in pretty darn good condition and I may leave it be. Luckily ALL the mirrors and lenses are prime.

I notice it has a declination assembly, but it appears to be incomplete.

Should be a fun winter project when Spokane spends nearly 100 days in solid frost.

Best all

Attached Image:

fct-150's attachment for post 58654

Just a few thoughts:

8) FS-152SV sitting in the office
grin Japanes super lucky zen observatory garden
:S Meade ETX-90 finder scope position
shocked Hino Optical Mizar 120SL observatory model
:C SR-4mm eyepiece with a 3x barlow in a 60mm refractor
8O Zeiss Victory 7x42 SFs
wink Having over 135 vintage oculars to play with
smile My life surrounded by wonderful friends and impeccable optics
Posted 08/21/2014 02:46AM #1
Ah, HA!! Just what I though; a Cave Richest Field 8!

Just a few thoughts:

8) FS-152SV sitting in the office
grin Japanes super lucky zen observatory garden
:S Meade ETX-90 finder scope position
shocked Hino Optical Mizar 120SL observatory model
:C SR-4mm eyepiece with a 3x barlow in a 60mm refractor
8O Zeiss Victory 7x42 SFs
wink Having over 135 vintage oculars to play with
smile My life surrounded by wonderful friends and impeccable optics
Posted 08/21/2014 11:30AM #2
Awesome, that will make a nice project. grin

[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue grin
Amateur Imager
Posted 08/26/2014 07:41PM | Edited 08/26/2014 08:00PM #3
Andy, the 1976 Silver Anniversary Cave catalog lists that scope with the two finder/guide scopes & fully-rotating tube as a newly introduced Astrola Dual-capability 8" f/4.5 reflector available in either lightweight or heavy-duty versions with a null-figured Pyrex primary mirror with enhanced aluminizing & quartz overcoating with a focal length of 36". A 20mm extreme wide-field Erfle (80-degree AFOV = 2-degree TFOV) & 3X tele-negative lens & either a 10mm or 6mm Ortho was included in the base price. The tele-negative amplifier gives very fine definition on the moon, planets & double stars according to the catalog. The same catalog also lists the RFT version without a rotating tube or finder & guide scopes. The heavy-duty version has a full-thickness mirror & 1.5" shafts and the Lightweight version has 1" shafts along with a thinner primary mirror, reducing instrument weight by 25 pounds (HD = 75# & LW = 50#). I have a 10" Meade f/4.5 Starfinder (of 1990's vintage per it's 2.4" secondary) which after 9 months of evaluation has star tested as having a very good figure comparable with my 8" f/7 & 6" f/8 Discovery-made mirrors and certainly it is Seeing-limited. I employ a Barlow with it when observing the planets at high power and it then bests my perfect-optics Cave 8" f/7 due to the greater light-grasp affording more contrast. So I'd expect similar high-power results with your Cave scope when a Barlow is used with it. This Dual-capability equatorial instrument was designed for maximum portability with extremely rapid breakdown or re-assembly (ready for observing in two minutes or less) and can store in the trunk of even a small auto. The Dec. slo-mo on yours appears non-Cave, at least per 1976 or earlier examples (the manual slo-mo on my 1971 Cave & those illustrated in the '76 catalog are the same but not like yours as they have no sector arm but a 4" gear wheel & worm instead for both manual & motorized versions.
Posted 02/19/2015 04:54PM #4
I sold off my Cave Astrola 12.5 with massive observatory mount for $2000 a couple of years ago! And that was with a superb upgrade to Byers 11.3 inch drive! I had not used for 10 years just festering in an old dome. All I can remember now is that the LEAD counterweight was 100 pounds! The thing was a beautiful monster and had a superb mirror! The stock drive was terrible...always fighting it trying to DS imagery. Anyway - your scope looks great and will be quite the showpiece! Tom Dey

29-inch Dob in a dome
36-inch upgrade soon
LUNT 80/80 solar scope
FLI 6803 cam
APM 100mm APO Binos
JMI RB-16 Night Vision Binos
Zeiss 20x60 IS binos
Posted 10/03/2018 04:29PM | Edited 10/03/2018 04:35PM #5
My opinion only: Cave 8" scope, even f/4.5, is pushing the limit of the small Astrola mount with 1" axes.
The additional weight of that guide-scope which is apparently unbalanced and about 7" from the scope centerline further complicates the stability issues faced by this small mount with its heavy and unbalanced payload.
A tube counterweight would help.  See Sam Brown for how to do it.

Attached Image:

Kenttolley10's attachment for post 159194