Jon Isaacs
Postmaster
Reged: 06/16/04
Loc: San Diego and Boulevard, CA
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Re: what to look for in used 10 inch Parks Dob
[Re: KerryR]
#5690985 - 02/20/13 02:11 PM
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It's pretty easy to recognize truly bad bearings-- the differential between the force required to initiate movement and that needed to continue the movement can be pretty obvious, and if it is, it suggests a problem.
My concern is that the base is a non-standard design and for an OTA that heavy, it does look a bit undersized and with small altitude bearings.
My gut feeling is that this scope will be a project, the OTA probably weighs about what a 12 inch F/5 does, from what I can see in the photo, the OTA is long...
Jon
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KerryR
Carpal Tunnel
Reged: 12/05/07
Loc: SW Michigan
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Re: what to look for in used 10 inch Parks Dob
[Re: Jon Isaacs]
#5691132 - 02/20/13 03:18 PM
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It's pretty easy to recognize truly bad bearings-- the differential between the force required to initiate movement and that needed to continue the movement can be pretty obvious, and if it is, it suggests a problem.
My concern is that the base is a non-standard design and for an OTA that heavy, it does look a bit undersized and with small altitude bearings.
My gut feeling is that this scope will be a project, the OTA probably weighs about what a 12 inch F/5 does, from what I can see in the photo, the OTA is long...
Jon
You could certainly be right.
The open design of the base actually looks pretty similar to the Skyquest XT12i (similar ota weight), but with an additional vertical stablilizer on the sides not present on the Orion XTi. The apparently 5-6ish" diameter alt bearings probably are a little small for ensuring best motions, but their pretty close to, if not bigger than, Orion's 12i alt bearing diameter . Plus they look like they have laminate on them, while most Asian dobs are glossy plastic on teflon.
The ota is heavy-- 42# according to Parks's website vs. 29# for the Orion 10i ota. I could certainly see potential for focus wiggles given the weight. But, the plywood might dampen more quickly as well as be more rigid in the first place, so it might not be any worse than the Orion despite the additional weight. If the base is glued and screwed, there's potential for it to be nice and solid. A lot would depend on things we can't see in the image.
The Parks is 52" (according to their website), vs. 48" for the Orion. I don't think this would prevent the ota from fitting in a car, though it certainly adds to the clunk factor.
I could see how it COULD end up being a project scope (I'd venture to say most Dobs are, commercial or otherwise), but probably not more so than an Orion equivalent. It's obviously impossible to know from a photo for sure, but the construction sure LOOKS well thought out and executed if maybe a little 'wispy' (but also lighter-- maybe a good thing).
Hopefully, the OP will get a chance to take a peek through it, either at stars or a daytime target. That would answer the questions.
Edited by KerryR (02/20/13 05:19 PM)
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azure1961p
Postmaster
Reged: 01/17/09
Loc: USA
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Re: what to look for in used 10 inch Parks Dob
[Re: KerryR]
#5691905 - 02/20/13 10:45 PM
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At $550 I wouldn't care about the recoat. It's still a deal on what probably a great scope. I would take it over a new dob by anyone else for the same aperture and f ratio.
Pete
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Pinbout
Post Laureate
Reged: 02/22/10
Loc: Montclair
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Re: what to look for in used 10 inch Parks Dob
[Re: azure1961p]
#5692382 - 02/21/13 09:14 AM
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I would take it over a new dob by anyone else for the same aperture and f ratio.
Even Teeter's new 10in travel dob?
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Jon Isaacs
Postmaster
Reged: 06/16/04
Loc: San Diego and Boulevard, CA
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Re: what to look for in used 10 inch Parks Dob
[Re: azure1961p]
#5692421 - 02/21/13 09:46 AM
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At $550 I wouldn't care about the recoat. It's still a deal on what probably a great scope. I would take it over a new dob by anyone else for the same aperture and f ratio.
Pete
I have had my 10 inch F/5 Generic Asian Dob for about 10 years, it's been a good scope, solid optics and has required a minimum of tweaks, most of which are now standard. I have some scopes with fancier names but this GSO is a good scope and I wouldn't be trading it for this Parks unless I knew more about the Parks.
I am looking at the photo of this Parks Dob, the base design is what concerns me the most. It's not clear to me how the altitude bearings work, to my eye, the one bearing I can see does not appear to be the standard trunion design. It could be that it works great, it could be that it needs a complete rebuild.
To Kerry's points, the difference between a 48 inch long OTA and a 52 inch long OTA can be quite critical when it comes to fitting the scope into a car. I know my 10 inch F/5 fits nicely across the back seat of our 1999 Honda Accord, the Parks might fit but probably would require some shenanigans.
My thinking goes like this: Over the years I have purchased a fair number of second hand Dobsonians. With customs scopes, I have had some surprises that required major rebuilds. If the Original Poster, Cordite33, is ready to take on what might be a project scope, it's probably a reasonable choice.
Jon
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nirvanix
Pooh-Bah
Reged: 06/07/07
Loc: Saskatoon, SK
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Re: what to look for in used 10 inch Parks Dob
[Re: Jon Isaacs]
#5692503 - 02/21/13 10:43 AM
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I agree with you Jon. A picture of a telescope with the name Parks on it is not a guarantee of this scope being quality. Brand name obsession. I wouldn't pay anywhere near the asking price unless I brought a seasoned stargazer along to "try before you buy". Not when I know that for half that price I could get a 10" Orion/Zhumell that someone has been using and can attest to it's performance.
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KerryR
Carpal Tunnel
Reged: 12/05/07
Loc: SW Michigan
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Re: what to look for in used 10 inch Parks Dob
[Re: nirvanix]
#5692571 - 02/21/13 11:39 AM
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Parks's reputation for quality optics is not brand-name obsession-- it's based on their production of excellent optics and tubes over a period of many, many years.
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dscarpa
Carpal Tunnel
Reged: 03/15/08
Loc: San Diego Ca.
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Re: what to look for in used 10 inch Parks Dob
[Re: cordite33]
#5692607 - 02/21/13 12:00 PM
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I had a 6" F/8 with a Parks mirror 30 plus years ago and it was an excellent scope. My IM-715D has nothing on it performance wise. Provided everything works I would go with the Parks over a GSO. David
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Jon Isaacs
Postmaster
Reged: 06/16/04
Loc: San Diego and Boulevard, CA
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Re: what to look for in used 10 inch Parks Dob
[Re: KerryR]
#5692620 - 02/21/13 12:11 PM
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Parks's reputation for quality optics is not brand-name obsession-- it's based on their production of excellent optics and tubes over a period of many, many years.
I have seen others whom I trust suggest otherwise.
They are old school, standard thickness and if I remember correctly, they provide a certificate that the mirror is "diffraction limited."
Jon
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nirvanix
Pooh-Bah
Reged: 06/07/07
Loc: Saskatoon, SK
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Re: what to look for in used 10 inch Parks Dob
[Re: KerryR]
#5692792 - 02/21/13 01:44 PM
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Parks's reputation for quality optics is not brand-name obsession-- it's based on their production of excellent optics and tubes over a period of many, many years.
Right here on CN I've read at least two people state they were not impressed with their Parks mirror. They were not new stargazers, so I'm assuming they understood collimation, cooldown, mounting, etc, but who knows? I realize that Parks had a great mirror maker named George Clement, but did he make every mirror? It all goes back to what I said previously, each scope is only as good as it proves out to be, so you can try before you buy or take a chance. You will learn something either way 
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Binojunky
Carpal Tunnel
Reged: 12/25/10
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Re: what to look for in used 10 inch Parks Dob
[Re: nirvanix]
#5692931 - 02/21/13 03:20 PM
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Parks mirrors were as follows, if you got a good one and the majority were good they were very nice performers, however they also put out some average ones and the odd lemon,it pays to look through one before parting with your hard earned cash, an earlier post saying they woudn,t care if the mirrors need a recoat its still a deal, is to me just nuts, what if the mirrors are not that great a performer?DA.
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KerryR
Carpal Tunnel
Reged: 12/05/07
Loc: SW Michigan
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Re: what to look for in used 10 inch Parks Dob
[Re: cordite33]
#5699719 - 02/25/13 11:43 AM
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OP:
I assume you checked this scope out this weekend. What did you think? What did you learn about it? What did you end up doing?
I'm curious to hear...
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cordite33
member
Reged: 02/13/13
Loc: western montana
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Re: what to look for in used 10 inch Parks Dob
[Re: KerryR]
#5700663 - 02/25/13 10:01 PM
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I haven't been able to break loose and go see it yet. It is about a 3 hour drive.
We have great dark skys here in Montana but it is often quite a drive to find used equipment.
I really appreciate all the comments and I'm sure they will help me make a final decision. The diversity of thoughts here reflect my own internal debates; one can buy a new low end dob for the same price and I've recently seen several, nearly new, for even less money. I definitely need to see it in person and evaluate it as best I can.
I will report back.
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cordite33
member
Reged: 02/13/13
Loc: western montana
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Re: what to look for in used 10 inch Parks Dob
[Re: cordite33]
#5700789 - 02/25/13 11:27 PM
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I've decided to go see it tomorrow. Seller says it is 9 years old and the receipt is $1500 for the OTA plus $499 shipping. He has no knowledge about the base. I told him I would only make the drive if he was flexible on the price and pointed to another used Dob in his town currently for sale for less money. He is flexible. So stay tuned for a full report tuesday pm.
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azure1961p
Postmaster
Reged: 01/17/09
Loc: USA
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Re: what to look for in used 10 inch Parks Dob
[Re: Jon Isaacs]
#5700837 - 02/26/13 12:12 AM
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It's pretty easy to recognize truly bad bearings-- the differential between the force required to initiate movement and that needed to continue the movement can be pretty obvious, and if it is, it suggests a problem.
My concern is that the base is a non-standard design and for an OTA that heavy, it does look a bit undersized and with small altitude bearings.
My gut feeling is that this scope will be a project, the OTA probably weighs about what a 12 inch F/5 does, from what I can see in the photo, the OTA is long...
Jon
If its identical to my PARKS 10" f/5 that I had and it appears to be, the weight is a clean or close 50 pounds. The glass is the real weight. My long 6', 10" wide Parks 8" OTA by contrast is a comfy 35 lbs.
Pete
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azure1961p
Postmaster
Reged: 01/17/09
Loc: USA
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Re: what to look for in used 10 inch Parks Dob
[Re: azure1961p]
#5700841 - 02/26/13 12:15 AM
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I wouldn't haggle too much at $550. If you get it for $500 or even $550 and the mount is worthless you hot a fantastic deal
Lol be nice to this guy.
Pete
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Deep13
Carpal Tunnel
Reged: 01/25/05
Loc: NE Ohio
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Re: what to look for in used 10 inch Parks Dob
[Re: KerryR]
#5700866 - 02/26/13 12:46 AM
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A Parks mirror will probably be better than a mass-produced Chinese mirror.
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nirvanix
Pooh-Bah
Reged: 06/07/07
Loc: Saskatoon, SK
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Re: what to look for in used 10 inch Parks Dob
[Re: Deep13]
#5701033 - 02/26/13 05:36 AM
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A Parks mirror will probably be better than a mass-produced Chinese mirror.
This is part of the mythology that persists at CN. Take a look around here at how many satisified Orion, Zhumell, Skywatcher, etc owners there are of 8, 10, or 12 inch dobs. In fact, if you get one of them you are almost certain of getting a good mirror, and have a reasonable chance at getting a great mirror like I did.
It's interesting to note that the refractor forum let go of this myth earlier than we have here in the reflector forum. People that buy refractors with Chinese lenses now expect to get very good optics, and they pretty much always do.
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Binojunky
Carpal Tunnel
Reged: 12/25/10
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Re: what to look for in used 10 inch Parks Dob
[Re: nirvanix]
#5701571 - 02/26/13 12:27 PM
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A Parks mirror will probably be better than a mass-produced Chinese mirror.
This is part of the mythology that persists at CN. Take a look around here at how many satisified Orion, Zhumell, Skywatcher, etc owners there are of 8, 10, or 12 inch dobs. In fact, if you get one of them you are almost certain of getting a good mirror, and have a reasonable chance at getting a great mirror like I did.
It's interesting to note that the refractor forum let go of this myth earlier than we have here in the reflector forum. People that buy refractors with Chinese lenses now expect to get very good optics, and they pretty much always do.
Agreed, DA.
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cordite33
member
Reged: 02/13/13
Loc: western montana
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Re: what to look for in used 10 inch Parks Dob
[Re: Binojunky]
#5702680 - 02/26/13 11:23 PM Attachment (7 downloads)
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Well, I think I bought a project but I'm well pleased.
Lets start with the good. The OTA appears unused and pristine. The mirrors, the tube, it is like well, new!! I'm sure the heavy end caps have helped keep it that way in storage. I can't say enough about the condition.
It has a 2 inch focuser and and an 8x50 finder both labled Parks. The finder must be a red dot?? It has an on/off switch and a small battery compartment.
Edited by cordite33 (02/27/13 12:17 AM)
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