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older 8" blue sonotube dob

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#1 precaud

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Posted 23 September 2013 - 12:12 PM

Who made 8" blue-painted sonotube dobs 12+ years ago with the focuser on the right side? Looks like your basic F/6 unit. I'm going to see one tonight, the seller doesn't know who made it. It doesn't look like a homemade job.

#2 Natty Bumppo

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Posted 23 September 2013 - 12:30 PM

Does it have a thick heavy single vane spider? If so my first guess would be a Coulter. Although Discovery PDHQ dobs are also blue with focuser on the right. Might be an 8" f/7 PDHQ.

#3 precaud

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Posted 23 September 2013 - 12:37 PM

Hmmm... I don't have a pic of the front, but I see spider mounting screws at quarter points. It's not long enough to be an F/7 - that would be a nice find if it was an F/7 Discovery, though!

#4 Jon Isaacs

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Posted 23 September 2013 - 12:40 PM

Does it have a thick heavy single vane spider? If so my first guess would be a Coulter. Although Discovery PDHQ dobs are also blue with focuser on the right. Might be an 8" f/7 PDHQ.


If it i 12 years old, it is unlikely that it's F/7, at that time they were pretty only making F/6's.

Any link or photos? Craigslist?

Jon

#5 precaud

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Posted 23 September 2013 - 12:49 PM

I don't know the age, only that is at least 12 years old. This is the only pic I have.

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#6 Jon Isaacs

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Posted 23 September 2013 - 02:58 PM

I saw that ad but I thought it was a 10 inch???

From the proportions it looks like a 6 inch to me. If it's an 8 inch, it's a long focal length.

Jon

#7 csrlice12

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Posted 23 September 2013 - 03:01 PM

As long as the optics are good, that thing will kill on planets........

#8 Natty Bumppo

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Posted 23 September 2013 - 03:11 PM

It looks like its setting on an Orion base, any chance it could be an old pre-Synta Orion? I don't recall what their older ones were like. Then again, the altitude bearings appear to be from a Meade Lightbridge. Could be a homebuilt "Frankenscope". I agree with Jon, 6 or 8", it's a long f/l.

#9 precaud

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Posted 23 September 2013 - 03:13 PM

Yeah, it's definitely not a 10", but I thought I'd break that news to him in person. He says it's 50"-ish high so that's why I thought 8" F6.

So it's not reminding anyone of anything from that period?

Agreed, the proportions look more like a 6". The base looks awfully squat even for a 6.

#10 Zamboni

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Posted 23 September 2013 - 03:59 PM

Definitely not a pre-synta orion. The earliest ones were white, later models were black.

I think that's a homemade job on an old Orion base. Just a guess.

#11 youngamateur42

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Posted 23 September 2013 - 05:34 PM

Looks like a home brewed scope (and tube) put on an Orion or similar mount. I've people do this before

#12 azure1961p

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Posted 23 September 2013 - 07:21 PM

That' looks like a ten inch wide tube - particularly if that's a 50mm finder. The finder is the wildcard here - if you get the mm on that then you can measure out the rest. It could potentially be a 10" scope . I'm looking for something to scale by and its elusive.

I agree its looks like a home brew - could be a great scope though with a custom mirror - you dont know . and just an FYI - there's a far better way to counter balance a reflector than the pic shows.

Pete



#13 precaud

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Posted 23 September 2013 - 11:29 PM

Well we were right, it is not a 10" but an 8" F/6 homebuilt. Could very well have been made from a kit. The guy lives in a green zone (close to blue) and the views were fantastic even before it turned fully dark. The primary had no center spot, and in 10 years of owning it, he had never collimated it. I was inclined to say no thanks but decided to collimate it (it was WAY out) and take a peek. The primary was filthy but clearly very good - stars were sharp, 250lpi Ronchi looked clean and straight, and star test was perhaps the best I've seen, looking the same on both sides of focus. Could very well be a premium mirror. I looked on the back of it for any identifying marks but saw none except the focal length written. The mount and altitude bearings need a little TLC but nothing difficult. For seventy bucks it will be fun to clean up and play with.

#14 precaud

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Posted 24 September 2013 - 09:19 AM

I saw that ad but I thought it was a 10 inch???


So, Jon, inquiring minds want to know: You're in CA; do you watch CL ads for telescopes as far away as NM ?

#15 Jon Isaacs

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Posted 24 September 2013 - 12:18 PM

I saw that ad but I thought it was a 10 inch???


So, Jon, inquiring minds want to know: You're in CA; do you watch CL ads for telescopes as far away as NM ?


No..., I pretty much stick with San Diego and every so often ajoining counties. There are times when I look at Phoenix.

In this case, I saw you were in New Mexico so I did a search on Dobs...

It's looks like you good a nice scope. Any more details? Focuser, type of mirror cell, secondary? Over the years, I have gotten some good deals on 8 inch F/6 Dobs but I never end up keeping them because there never seems to be a reason to choose an 8 inch F/6 over my 10 inch F/5...

Jon

#16 Calypte

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Posted 24 September 2013 - 12:41 PM

It looks like its setting on an Orion base, any chance it could be an old pre-Synta Orion?

Those were made by Pirate Telescopes, which morphed into Discovery. A friend of mine made them, DBA Pirate. The scope in the picture doesn't look to me like a Pirate or Orion scope.

#17 Jon Isaacs

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Posted 24 September 2013 - 01:18 PM

It looks like its setting on an Orion base, any chance it could be an old pre-Synta Orion?

Those were made by Pirate Telescopes, which morphed into Discovery. A friend of mine made them, DBA Pirate. The scope in the picture doesn't look to me like a Pirate or Orion scope.


My very first Dob was a used Pirate Instruments 8 inch F/6. It was pretty crude, single wire secondary mount and the mirror cell was made from lead for balance...

Here's a photo of it along with my 12.5 inch F/4.06 in it's original incarnation..

JOn

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#18 precaud

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Posted 24 September 2013 - 01:23 PM

In this case, I saw you were in New Mexico so I did a search on Dobs...


Ah, you were just being resourceful, then :)

It has a 1.25" helical focuser, 6x30 finder sitting way too close to the OTA for comfortable use, 4-vein spider, the primary is glued to a laminated particle board cell. The primary is absolutely filthy, the scope was stored pointing straight up with no front cover. I'm painting the exposed particle board on the cell prior to cleaning the mirror to water-proof it. It was definitely made from a kit - all of the hardware is very consistent - blackened, hex heads, etc. Will post pics later.

#19 Calypte

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Posted 24 September 2013 - 10:09 PM

My very first Dob was a used Pirate Instruments 8 inch F/6. It was pretty crude, single wire secondary mount and the mirror cell was made from lead for balance...

I asked my friend, and he agrees (i.e. "crude"). But he points out that the scope sold for only $299.

#20 Jon Isaacs

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Posted 25 September 2013 - 06:35 AM

My very first Dob was a used Pirate Instruments 8 inch F/6. It was pretty crude, single wire secondary mount and the mirror cell was made from lead for balance...

I asked my friend, and he agrees (i.e. "crude"). But he points out that the scope sold for only $299.


Curtis:

Is your friend still making mirrors/telescopes ? I have a sneaky suspicion the answer is yes..

Jon

#21 Calypte

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Posted 25 September 2013 - 10:43 AM

Is your friend still making mirrors/telescopes ? I have a sneaky suspicion the answer is yes..

Jon

Yes. Mirrors, both primaries and secondaries. Mostly contract work. No scopes.

#22 precaud

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Posted 25 September 2013 - 06:54 PM

I forgot to take pics before I started, but the mirror cleaned up perfectly. There must be something protective about NM dust, because this is now the second mirror that I've bought that had years of local dust accumulation on it that was in fabulous shape underneath!

The blue-green hue of plate glass is clearly visible, as well as the particle board cell.

I taped between the cell and mirror to prevent water from getting in between them. Is there any reason not to leave the tape in place?

Next job is to center spot it (with the photo centering technique, of course!).

Oh, and in the background is my 16" mirror which just arrived with a new figure and new coat... :jump:

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#23 precaud

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Posted 25 September 2013 - 06:57 PM

In the off chance that someone might recognize the components and identify where this kit came from, I'll post a couple more pics. Here's a view of the OTA front.

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#24 precaud

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Posted 25 September 2013 - 07:01 PM

And one of the 4" molded plastic altitude bearings. The previous owner thought it moved too easily and had wrapped duct tape around it for resistance. The tape adhesive had hardened long ago and was a pain to remove. Also visible is where the original kit builder had misplaced the bearings and covered up the gap with blue marker pen... sigh.

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#25 azure1961p

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Posted 25 September 2013 - 09:58 PM

It could still be a gem despite the rough around the edges mechanics . You might want to spray the tube with Kilz to coverup ink before you paint to prevent pigment seepage. I'm curious to see how this one performs.

Pete






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