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Sears 6339-A (RAO) 76mm f/15.8

Classic Refractor
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#1 monolithic

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Posted 16 February 2024 - 03:07 PM

I am now the proud owner of a well-preserved Sears 6339-A 76mm refractor. The serial number dates it to 1968, and it is in great condition, only needing some tiny touchups with black paint and maybe some refinishing on the legs. The objective is pristine. It is a complete set in the box, coming with everything listed in the packing diagram, including the manual and all the eyepieces (even the little Sun/Moon filters). Many of the components were in their original packaging.

 

I was so afraid of marring it I ended up using disposable gloves to assemble and operate the scope. Took it out last night and set it in a strange approximation of an altazimuth configuration (this was my first time using an equatorial mount). Despite mediocre conditions and lower altitude, I got an excellent view of the moon. I took it up to 200x with the 6mm Huygens. As far as I could see, the optics are extremely sharp and color-free, but I will have to come back on a better night to get a better picture. That said, these first impressions are quite promising!

 

Here is a picture with my 10" f/7 Dobsonian in the back.

 

20240216_132352.jpg


Edited by monolithic, 16 February 2024 - 04:17 PM.

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#2 Couder

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Posted 16 February 2024 - 03:17 PM

very nice acquisition.



#3 apfever

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Posted 16 February 2024 - 03:25 PM

I like the dob.

Is the that the one from fb without the box? posted in the 'ads' string.

$100 obo. loaded with everything except the box. Real nice. 

 

If not, yours looks like that. Nice. 


Edited by apfever, 16 February 2024 - 03:27 PM.

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#4 oldmanastro

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Posted 16 February 2024 - 03:50 PM

It looks mint. These are wonderful telescopes with excellent optics. The 6mm Huygens eyepiece is quite good. It was usually color coded in red but there are also black ones. Get a .965" top 1.25" adapter to use it with standard and better eyepieces. The results will be great. Enjoy!


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#5 monolithic

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Posted 16 February 2024 - 04:43 PM

I like the dob.

Is the that the one from fb without the box? posted in the 'ads' string.

$100 obo. loaded with everything except the box. Real nice. 

 

If not, yours looks like that. Nice. 

Thank you.

I bought this on eBay from a gentleman in Pennsylvania. The listing was posted here in the Classics forum on the 12th. Ended up accepting the seller's counteroffer of $329.


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#6 deSitter

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Posted 16 February 2024 - 05:47 PM

I am now the proud owner of a well-preserved Sears 6339-A 76mm refractor. The serial number dates it to 1968, and it is in great condition, only needing some tiny touchups with black paint and maybe some refinishing on the legs. The objective is pristine. It is a complete set in the box, coming with everything listed in the packing diagram, including the manual and all the eyepieces (even the little Sun/Moon filters). Many of the components were in their original packaging.

 

I was so afraid of marring it I ended up using disposable gloves to assemble and operate the scope. Took it out last night and set it in a strange approximation of an altazimuth configuration (this was my first time using an equatorial mount). Despite mediocre conditions and lower altitude, I got an excellent view of the moon. I took it up to 200x with the 6mm Huygens. As far as I could see, the optics are extremely sharp and color-free, but I will have to come back on a better night to get a better picture. That said, these first impressions are quite promising!

 

Here is a picture with my 10" f/7 Dobsonian in the back.

 

attachicon.gif 20240216_132352.jpg

Nice! Don't worry about babying it!

 

-drl



#7 Joe Cepleur

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Posted 17 February 2024 - 11:49 AM

Wonderful! Equatorial mounts are easy to use for visual astronomy. It only gets fussy in astrophotography.

There is a scale on the side of the mount where it connects to the tripod and angles back and forth. Set that to your latitude. Then, cup the mount in your hands so that the hinge is near your wrists, with your fingers following the tube upwards. Find Polaris, and point your cupped hands at it. Done! Errors in pointing will be small enough to correct with the slow motion controls. You will get better at aligning over time.

#8 jragsdale

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Posted 17 February 2024 - 12:31 PM

Gorgeous scope, happy you went with that one over my rough-n-tumble 6344.


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#9 Garyth64

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Posted 17 February 2024 - 07:48 PM

I've had a few Sears 6339a scopes over the last few years.  I liked everyone.  I've even had a few Tasco 10TE scopes, they have the same excellent RAO lens.

 

I didn't care for the mount.  I liked putting the scope on a CG-5 mount for outreach events.

 

AO 6339a posing.jpg

 

This next photo has an interesting 10" telescope with an aluminum tube.  It looks like the "dob" in the above pictures.

 

viewing 6 25 b.jpg

-the 10" reflector shown in the op use to be mine.  The 10" and a 3" have been friends for a long time.

 

Here's one of my 6339a scopes at an event:

 

Heritage Park 1.jpg

 

Best thing was to make or use an adapter to use 1-1/4" eyepieces.  The views just got better.


Edited by Garyth64, 17 February 2024 - 07:59 PM.

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#10 Garyth64

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Posted 17 February 2024 - 07:55 PM

I like the dob.

Is the that the one from fb without the box? posted in the 'ads' string.

$100 obo. loaded with everything except the box. Real nice. 

 

If not, yours looks like that. Nice. 

I like the dob too. I made the scope, ground, polished, and figured the mirror back in 1975, and refurbished it with an aluminum tube about 2012.  I sold the OTA a few years ago.  (I still list it in my signature.)


Edited by Garyth64, 17 February 2024 - 07:55 PM.

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#11 monolithic

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Posted 21 February 2024 - 12:05 AM

Here are some more pictures of the 6339-A.

Lunar this evening, and then Jupiter after dark. Moon was crisp, Jupiter showed a respectable amount of detail for the aperture. I'll post my notes in a separate message.

sears_evening_moon.jpg  sears_jupiter.jpg

The mount. In great shape aside from some small dings, functions perfectly, if a little stiff in the RA axis.

sears_eq.jpg  sears_mount_lower.jpg

The eyepieces and focuser plate with RAO marking.

eyepieces.jpg  searsplate.jpg rao_mark.jpg

The objective. The glass is perfect; any dots you may see are dust.

sears_lens.jpg


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#12 monolithic

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Posted 21 February 2024 - 12:06 AM

A through-the-eyepiece photo of the southern Moon I took with my phone last night. The live view was considerably sharper.

sears_southern_moon.jpg


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#13 monolithic

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Posted 21 February 2024 - 12:08 AM

Lunar this evening, and then Jupiter after dark. Moon was crisp, Jupiter showed a respectable amount of detail for the aperture. I'll post my notes in a separate message.

(6:31 PM) Sunset Moon is crisp. Had a little impromptu sidewalk astronomy session and showed two kids the whole Moon with the 22mm Kellner. (Didn't really focus on the Moon tonight, but last night I successfully used 200x to observe features like the southern craters, Tycho's tiered walls, structure in Bullialdus' central peak, and the shadow of Promontorium Laplace.)

(6:40 PM) Not much to see on Jupiter at the moment; the sky is still darkening and the GRS is not visible. Seeing is mediocre, maybe a bit below average, but the 3" aperture appears to cut through the atmosphere. Festoon activity subtly visible as patches on the underside of the NEB. Galilean moons are defined discs at 133x (9mm Huygens), even 96x (12.5mm Huygens). 133x seems to be the sweet spot for Jupiter, however I have nothing between 9mm and 6mm (200x).

(7:33 PM) Now that it's dark, contrast on Jupiter is better; very subtle turbulence is visible in the equatorial belts, and the patchy festoon activity is more apparent. No swooping trails like what can be seen with the 10"; unclear on whether this is because of the aperture, conditions, or the patches themselves simply not having trails. Admittedly the equatorial mount is growing on me. It's nice to be able to just sit in a chair and twist a knob to keep the target in view.

(7:46 PM) Satellite flew between Europa and Callisto.

(8:04 PM) Starting to be able to tease out features in the temperate zones. A slightly lighter band runs through the northern temperate region, and the southern temperate region is beginning to show the tiered bands and belts I see in the 10" so often. Not nearly as easy as with the latter scope, but present.

Wrapped up at around 8:45 because of the cold. Overall this scope is an excellent performer on the Moon, and a decent performer on Jupiter. With lunar, it seems to show most of what the 10" does, excluding kilometer-scale microdetail. It is more limited on the planets, and will surely be outclassed by the 10" on a stable night. The 3" and the 10" complement each other - the 3" as a quick-setup scope that works well under mediocre conditions, and the 10" as a powerhouse under good conditions. 


Edited by monolithic, 21 February 2024 - 10:47 PM.

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#14 monolithic

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Posted 21 February 2024 - 01:26 AM

I've had a few Sears 6339a scopes over the last few years.  I liked everyone.  I've even had a few Tasco 10TE scopes, they have the same excellent RAO lens.

 

I didn't care for the mount.  I liked putting the scope on a CG-5 mount for outreach events.

 

attachicon.gif AO 6339a posing.jpg

 

This next photo has an interesting 10" telescope with an aluminum tube.  It looks like the "dob" in the above pictures.

 

attachicon.gif viewing 6 25 b.jpg

-the 10" reflector shown in the op use to be mine.  The 10" and a 3" have been friends for a long time.

 

Here's one of my 6339a scopes at an event:

 

attachicon.gif Heritage Park 1.jpg

 

Best thing was to make or use an adapter to use 1-1/4" eyepieces.  The views just got better.

Hey! That's pretty cool. It's like the 6339-A and the 10" were meant to be together. smile.gif 
I can see why you put it on a different mount. I have to fight it a bit at high power and in breezy conditions, but for now I'm going to leave it on its original mount.
I'm about to order a 1.25" adapter; compatibility with modern eyepieces is going to be nice.


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#15 Garyth64

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Posted 21 February 2024 - 09:39 AM

Here are some more pictures of the 6339-A.

Lunar this evening, and then Jupiter after dark. Moon was crisp, Jupiter showed a respectable amount of detail for the aperture. I'll post my notes in a separate message.

attachicon.gif sears_evening_moon.jpg attachicon.gif sears_jupiter.jpg

The mount. In great shape aside from some small dings, functions perfectly, if a little stiff in the RA axis.

attachicon.gif sears_eq.jpg attachicon.gif sears_mount_lower.jpg

The eyepieces and focuser plate with RAO marking.

attachicon.gif eyepieces.jpg attachicon.gif searsplate.jpg attachicon.gif rao_mark.jpg

The objective. The glass is perfect; any dots you may see are dust.

attachicon.gif sears_lens.jpg

Excellent looking scope!


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#16 Senex Bibax

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Posted 21 February 2024 - 09:49 AM

The 6339A was an excellent scope, though I did pass mine on to a new owner last year. I second the comments about getting or making a 1.25" adapter. I don't know if the draw tubes changed at some point in the model's lifespan but mine was older and did not have a common or standard thread that would fit most available adapters. I made one out of a short 1 1/4" slip joint plumbing coupling.

 

VisualBackHack2
 
Which I later replaced with a surplus short extension tube that fit snugly over the draw tube:
 
Adapter1

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#17 Defenderslideguitar

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Posted 21 February 2024 - 07:04 PM

I had the 6336 Sears .... now with Oldmanastro

  We liked the green K 22 eyepiece

    but with the 1.25 adapter the scope really took off...

      Congrats

 

 

.


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#18 Joe Cepleur

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Posted 22 February 2024 - 06:44 AM

"Admittedly the equatorial mount is growing on me. It's nice to be able to just sit in a chair and twist a knob to keep the target in view."

The pleasure and functionality of these small equatorial mounts is part of the joy of using small Japanese refractors. At public outreach, it's great to have one knob for guests to need to turn to track an object. It makes them feel that learning how to operate a telescope would be possible for them. The knob only turns one way or the other, so the learning curve is minuscule.
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#19 Terra Nova

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Posted 22 February 2024 - 10:40 AM

And if someone has one in need of a mount, I know where they can get one cheap! lol.gif

 

https://www.cloudyni...ead/?p=13267749

 

And just the mount itself shipped, (no legs or tray):

 

https://www.cloudyni...ead/?p=13280777


Edited by Terra Nova, 22 February 2024 - 10:46 AM.

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