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cordite33
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Reged: 02/13/13

Loc: western montana
what to look for in used 10 inch Parks Dob
      #5689316 - 02/19/13 05:17 PM

Hi, first post here. I'm looking to get back into astronomy after many years away. What a great site this is. I've learned a lot by just searching and reading.

I have a chance to go look at at 10 inch Parks Dob this weekend that is for sale. Its one of those deals where the seller inherited it and doesn't know much about it other than it is valuable because they have the original receipt!
From my searches here it appears that Parks is well respected from a quality optics standpoint. Is there anything in particular I should look at to determine the telescopes value. It has some sort of custom base and only one eyepiece. Thanks in advance for any guidance you can give me.


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nirvanix
Carpal Tunnel


Reged: 06/07/07

Loc: Saskatoon, SK
Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5689339 - 02/19/13 05:31 PM

Are the movements of the scope (up and down and sideways) reasonably smooth? Do the two mirrors appear to be undamaged? No cracks, scratches, gouges, silver coating falling away? Don't worry about a bit of dust or dried dew spots - they can be cleaned with care. Because it's an unknown I wouldn't offer too much because you can buy a used Orion, Zhumell, etc 10" dob for about 300$ and you'll know from the owner that it works.

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GeneT
Ely Kid
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Reged: 11/07/08

Loc: South Texas
Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5689498 - 02/19/13 07:03 PM

Quote:

I have a chance to go look at at 10 inch Parks Dob this weekend




This is the key--to personally look over and test a telescope when buying used.


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KerryR
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Reged: 12/05/07

Loc: SW Michigan
Re: what to look for in used 10 inch Parks Dob new [Re: GeneT]
      #5689559 - 02/19/13 07:37 PM

I'm not sure, but I don't think Parks ever offered Dobsonain mounts.

So, the tube and/or mirror(s) may be Parks, and the Dobsonian mount is probably made by someone else.

Parks sold both tubes and mirrors by themselves, so you'd want to be sure what parts are actually Parks and what parts aren't. Parks tubes are all fiberglass, I believe, and easily recognizable as such. The primary will likely be labeled on the back with a serial number, hopefully a Parks logo, and some other information, probably depends on how old it is.

Parks mirrors have a solid reputation for being very good.

Parks fiberglass tubes are excellent-- excellent thermal characteristics, rigid but soft enough to help reduce vibrations, and nicely over-sized; both these things reduce tube currents far more effectively than the comparatively narrow metal ota's common to mass-market Dobs. Both these things are now nearly impossible/expensive to get, so this may be a pretty good score. Don't underestimate the value of non-thermally conductive tube materials.

Mirrors can be cleaned or re-coated if necessary, but you don't want to see ANY chips or scratches.

What's the asking price?


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cordite33
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Reged: 02/13/13

Loc: western montana
Re: what to look for in used 10 inch Parks Dob new [Re: KerryR]
      #5689721 - 02/19/13 09:03 PM Attachment (37 downloads)

He is asking $550

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cordite33
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Reged: 02/13/13

Loc: western montana
Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5689725 - 02/19/13 09:06 PM

It has some sort of location or tracking built into the mount as you can see the keypad. The owner was not at home when we talked so he couldn't give me any more details at the time.

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nirvanix
Carpal Tunnel


Reged: 06/07/07

Loc: Saskatoon, SK
Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5689819 - 02/19/13 10:03 PM

A Parks tube and optics with a custom base. The locator adds some value, maybe an extra $100. It looks like it was well cared for but check the mirrors for any damage. I'd be offering more like $400 for what I see if the optics are ok and the locator is working. These days used dobs are going for half price or less.

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azure1961p
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Re: what to look for in used 10 inch Parks Dob new [Re: nirvanix]
      #5689854 - 02/19/13 10:19 PM

Take it.

I had a PARKS F5 and I prefer the views through my PARKS 8" F/9 as its small secondary simply provides a look on everything I prefer. But my scope WAS at least good. The ronchi like for my 8" they made later on was ruler straight - completely. Too, another 10" f/5 by PARKS was reviewed by sky and tel as so good it would produce essentially perfect star images. They based it on the ronchi. Other mirrors tested in that article failed behind the parks, notibly MEADE. I forgot the others but recall the PARKS ten beat them all - hence my PARKS purchases.

If you don't mind the f/5 and most folks don't, it may be the best ten you'll ever look through. At the price its going at - you've got a bargain sitting there.

Pete


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Jon Isaacs
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5689879 - 02/19/13 10:34 PM

Quote:

It has some sort of location or tracking built into the mount as you can see the keypad. The owner was not at home when we talked so he couldn't give me any more details at the time.




It looks like a Parks tube on a custom mount. It looks big, long and heavy. A major virtue of the Asian 10 inch F/5 Dobsonians is that they were carefully designed to be compact, they fit in smaller cars and are of a reasonable weight. This one looks like a handful.

The mount is also an unknown. It looks to be a one-off design that did not follow common practice, it might work great, it might not. I don't recognize the electronics, maybe someone does...

A new 10 inch F/5 from Apertura, Astronomics or Zhumell is right at $500 shipped to your door. My gut feeling is that this Parks tube on a Dob mount is a bit clunky, something of a project.

Would this be your first scope? Where are you located?

Jon


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azure1961p
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Re: what to look for in used 10 inch Parks Dob new [Re: azure1961p]
      #5689917 - 02/19/13 10:56 PM

I'd laugh if that was the OTA I sold in New Hampshire. I too built a dob mount for it but ended up jus selling the tube.

Pere


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Mirzam
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Re: what to look for in used 10 inch Parks Dob new [Re: azure1961p]
      #5690353 - 02/20/13 08:23 AM

The bearings on the mount are on the small side. Perhaps they have some sort of tension adjustment? This would aid in maintaining balance when using eyepieces of different weights. It is nice to also have the tube rings though.

If the coatings on the primary are bright and undamaged then the price is not too bad. The fiberglass tube will be heavy but is an upgrade from the typical steel tubes offered by the Chinese makers. If you have to have the mirrors recoated figure on about $100 unless you live close to a coating facility (to eliminate shipping costs). Obviously the recoating cost should influence the price.

If the scope comes with any decent eyepieces that would also be a plus.

JimC


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Mirzam
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Re: what to look for in used 10 inch Parks Dob new [Re: Mirzam]
      #5690355 - 02/20/13 08:25 AM

You mentioned the receipt. If the coatings are more than 15 years old I would absolutely want a recoat.

JimC


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KerryR
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Loc: SW Michigan
Re: what to look for in used 10 inch Parks Dob new [Re: Mirzam]
      #5690519 - 02/20/13 10:00 AM

Looks well built.

One nice feature is the use of tube rings-- this will allow you to put the eyepiece where you want it, and allow you to balance the scope easily, without counterweights, should you change things out on the front end.

Parks tubes weigh a LOT more than the steel Asian variety. This can help make the movements smoother-- seems to take a certain heft before Dob bearings enter the truly butter-smooth realm. This only applies if the bearings are done correctly, but it should be pretty easy to tell-- when you push the tube there should be no stick-jerk action. It's alright if they the movements feel stiff, as long as they are smooth. You shouldn't feel that you have to apply a lot pressure to start the movement, but then far less as soon as it begins to move.

As I mentioned earlier, there's much to recommend to the thermal characteristics of over-sized fiberglass tubes, so I see that as a plus for the scope. But, it does you no good if you can't easily get the thing out the door!

It's nice that the tube has dust covers for both ends. You don't see that very often.

If everything fits in your car, I can't see much reason not to go for it, as long as the movements feel super-smooth to you. I think the asking price is quite fair, but no reason not to haggle.


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The Planetman
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Reged: 01/27/06

Loc: Western KY
Re: what to look for in used 10 inch Parks Dob new [Re: KerryR]
      #5690606 - 02/20/13 10:42 AM

Quote:

I'm not sure, but I don't think Parks ever offered Dobsonain mounts...




Yes, Parks offered dobs back in the late '80's/early 90's. But this is not the mount that they used. It is definitely an aftermarket.

I had a 10" f/5 Z-Scope -who remembers those scopes?- and it was built with Parks optics. It was a killer scope! Optics were great! But like any telescope/optics manufacturer, they can make a really great one or a not so really great one....

Check to see if the mirror has "Parks" etched on the back. Also, check to see if the optician signed it. I've had three mirrors, one 8" and two 10", that were made by George Clements and they were all nice.


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Jon Isaacs
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Re: what to look for in used 10 inch Parks Dob new [Re: KerryR]
      #5690618 - 02/20/13 10:50 AM

Quote:

This only applies if the bearings are done correctly, but it should be pretty easy to tell-- when you push the tube there should be no stick-jerk action. It's alright if they the movements feel stiff, as long as they are smooth. You shouldn't feel that you have to apply a lot pressure to start the movement, but then far less as soon as it begins to move.




In my experience, it is very difficult to judge the action of a Dobsonian mount unless one is out under the stars. A mount can seem nice and smooth to the touch, most do, but looking a target at higher magnifications, small imperfections are highly magnified. Stiction results in overshoot, vibration, it only takes a tiny fraction of a millimeter to mess things up.

Jon


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dpwoos
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Re: what to look for in used 10 inch Parks Dob new [Re: Jon Isaacs]
      #5690644 - 02/20/13 11:11 AM

I agree - the only way to know the worth is to observe with the scope. If the seller isn't interested in facilitating that then I would pass.

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rflinn68
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Reged: 03/09/12

Loc: Arkansas
Re: what to look for in used 10 inch Parks Dob new [Re: Jon Isaacs]
      #5690689 - 02/20/13 11:37 AM Attachment (12 downloads)

Quote:

It has some sort of location or tracking built into the mount as you can see the keypad.




Quote:

I don't recognize the electronics, maybe someone does...A new 10 inch F/5 from Apertura, Astronomics or Zhumell is right at $500 shipped to your door.




It looks exactly like the Hand Controller that came with my Orion XT10i. The 10" Apertura, Astronomics, Zhumell dobs for $500 new do not include the hand controller. Those cost about $750. My guess is it is a Push-To object locator and does not have a tracking motor. These are still nice to have if they work right. You just need to know a couple stars then you find and center them in the eyepiece and you are ready to go. It will show you up and down (ALT) and side to side (AZ) arrows with a set of numbers that will count down (or up if you're going the wrong way) as you move the scope to the object you are wanting to observe. If this scope has a nice mirror made by Parks I'm sure it would be worth the asking price assuming everything is in good working order. Looks nice to me.


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KerryR
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Re: what to look for in used 10 inch Parks Dob new [Re: Jon Isaacs]
      #5690694 - 02/20/13 11:40 AM

Quote:

Quote:

This only applies if the bearings are done correctly, but it should be pretty easy to tell-- when you push the tube there should be no stick-jerk action. It's alright if they the movements feel stiff, as long as they are smooth. You shouldn't feel that you have to apply a lot pressure to start the movement, but then far less as soon as it begins to move.




In my experience, it is very difficult to judge the action of a Dobsonian mount unless one is out under the stars. A mount can seem nice and smooth to the touch, most do, but looking a target at higher magnifications, small imperfections are highly magnified. Stiction results in overshoot, vibration, it only takes a tiny fraction of a millimeter to mess things up.

Jon




Agreed.

But it's not always possible to do so, so the OP may have to do it by feel as best he can.

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.

Another 'error' that can be easy to detect is a significant difference between alt and az friction, most obvious with Dobs with (un-tuned) lazy-susan az bearings.

It is, of course, much more difficult to recognize the subtle 'over shoot' of close-but-not-actually-good bearings without actually looking through the scope at high power.

Really bad movement might suggest the need for heavier duty mods that the OP might want to avoid, such as having to re-do the laminate on a bearing surface.

Close-to-good bearings often respond well to movement of bearing pads, cleaning bearing pads, sanding bearing pads, wax, Sailcoat, etc.; things the OP might not mind trying.

Point is, definitely give the scope a push or two and look for glaring errors, and take the results of a pass with a grain of salt if not actually looking through the scope.

Failing stars, a daylight trial on a distant target at high powers would help.


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Binojunky
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Reged: 12/25/10

Re: what to look for in used 10 inch Parks Dob new [Re: KerryR]
      #5690828 - 02/20/13 12:51 PM

To be honest if your getting back into the hobby and thinking of spending around $550 or so, I would be inclined to go with a new scope,a 8 or 10 inch dob would be ideal.
With new you have recourse if their are problems, the mirror coatings would be new, the Parks scopes though good in their day are heavy, some came with only 1.25" focusers etc,you may be buying a pile of problems, JMTCW,DA.


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KerryR
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Re: what to look for in used 10 inch Parks Dob new [Re: Binojunky]
      #5690876 - 02/20/13 01:15 PM

I bet the focuser is 2".

It sure doesn't LOOK like a hack-job mount. It looks like someone took a bit of time and care to build the mount and retrofit the locator. 'Course, what can I actually tell from a photo?

Parks mirrors are usually quite good. So are many of the current Asian mirrors, but it's always a gamble. I'd gamble on the Parks mirror before I gambled on an Asian mirror.

New scopes in a similar price range typically take some work to get their motions butter-smooth anyway, and their narrow metal tubes are a thermal drag, though commercial inserts and/or fans help reduce much of the issue.

Parks currently (I thought they were out of business??) lists their 10" f5's at $1,500 ota only. This makes the $550 mounted scope with push-to look pretty darn good to me. There'd have to be something pretty wrong with it for it to be a bad deal, assuming it fits in the OP's car.

OP: Let us know what the Receipt says (cost, date, etc.).

Edited by KerryR (02/20/13 01:17 PM)


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Jon Isaacs
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Re: what to look for in used 10 inch Parks Dob new [Re: KerryR]
      #5690985 - 02/20/13 02:11 PM

Quote:


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
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Re: what to look for in used 10 inch Parks Dob new [Re: Jon Isaacs]
      #5691132 - 02/20/13 03:18 PM

Quote:

Quote:


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
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Re: what to look for in used 10 inch Parks Dob new [Re: KerryR]
      #5691905 - 02/20/13 10:45 PM

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
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Re: what to look for in used 10 inch Parks Dob new [Re: azure1961p]
      #5692382 - 02/21/13 09:14 AM

Quote:

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
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Re: what to look for in used 10 inch Parks Dob new [Re: azure1961p]
      #5692421 - 02/21/13 09:46 AM

Quote:

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
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Re: what to look for in used 10 inch Parks Dob new [Re: Jon Isaacs]
      #5692503 - 02/21/13 10:43 AM

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
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Re: what to look for in used 10 inch Parks Dob new [Re: nirvanix]
      #5692571 - 02/21/13 11:39 AM

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
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5692607 - 02/21/13 12:00 PM

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
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Re: what to look for in used 10 inch Parks Dob new [Re: KerryR]
      #5692620 - 02/21/13 12:11 PM

Quote:

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
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Re: what to look for in used 10 inch Parks Dob new [Re: KerryR]
      #5692792 - 02/21/13 01:44 PM

Quote:

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
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Re: what to look for in used 10 inch Parks Dob new [Re: nirvanix]
      #5692931 - 02/21/13 03:20 PM

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
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5699719 - 02/25/13 11:43 AM

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
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Reged: 02/13/13

Loc: western montana
Re: what to look for in used 10 inch Parks Dob new [Re: KerryR]
      #5700663 - 02/25/13 10:01 PM

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
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Reged: 02/13/13

Loc: western montana
Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5700789 - 02/25/13 11:27 PM

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
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Re: what to look for in used 10 inch Parks Dob new [Re: Jon Isaacs]
      #5700837 - 02/26/13 12:12 AM

Quote:

Quote:


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
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Re: what to look for in used 10 inch Parks Dob new [Re: azure1961p]
      #5700841 - 02/26/13 12:15 AM

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
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Re: what to look for in used 10 inch Parks Dob new [Re: KerryR]
      #5700866 - 02/26/13 12:46 AM

A Parks mirror will probably be better than a mass-produced Chinese mirror.

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nirvanix
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Re: what to look for in used 10 inch Parks Dob new [Re: Deep13]
      #5701033 - 02/26/13 05:36 AM

Quote:

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
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Re: what to look for in used 10 inch Parks Dob new [Re: nirvanix]
      #5701571 - 02/26/13 12:27 PM

Quote:

Quote:

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
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Re: what to look for in used 10 inch Parks Dob new [Re: Binojunky]
      #5702680 - 02/26/13 11:23 PM Attachment (8 downloads)

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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cordite33
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5702689 - 02/26/13 11:27 PM Attachment (11 downloads)

Please excuse the picture quality. It was dark when I got home but I wanted to post some photos anyway.

Back of mirror.


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cordite33
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5702694 - 02/26/13 11:29 PM Attachment (8 downloads)

Looking down the other end.

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cordite33
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5702697 - 02/26/13 11:30 PM Attachment (12 downloads)

Certificate. Signed George ???

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cordite33
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5702727 - 02/26/13 11:47 PM Attachment (12 downloads)

So what's the project? That darn homemade mount!

When I got there the seller had it setting in the mount but not attached. You recall he was selling for deceased uncle. When we went to attach it he, and I discovered that he had no mounting bolts. Takes a 1/4 bolt on each side. The mount is obviously homemade and unfinished. The wood is untreated and I see pencil marks remaining from the build.

So I told the seller I could not evaluate it with the parts missing. Told him I liked the telescope and would like to buy it but as far as I was concerned the mount was a throw in to the deal. I certainly do not have the experience to evaluate the potential of the mount so I'm assuming little to none. I quoted him a very modest price, he countered and I upped my offer just a bit and we loaded it up. I think I got a great deal.
Ideally, I will get it mounted up and things will be great but I suspect not. I will post some pictures and perhaps you can tell me if the mount has any potential at all. I know that the rings need to be shimmed or tightened as the tube wants to slide down when in the vertical position.

Edited by cordite33 (02/27/13 01:27 AM)


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cordite33
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5702731 - 02/26/13 11:50 PM Attachment (9 downloads)

a picture of the mount

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cordite33
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5702735 - 02/26/13 11:53 PM Attachment (10 downloads)

another

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cordite33
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5702750 - 02/26/13 11:58 PM Attachment (9 downloads)

the intelliscope powers up so perhaps it will be of value

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cordite33
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5702753 - 02/27/13 12:03 AM Attachment (7 downloads)

I found a couple of very long bolts to get it in the mounts. I had no shims so there is no compression on the sides so it is shaky.

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cordite33
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5702759 - 02/27/13 12:08 AM Attachment (10 downloads)

So I am a happy camper. Even if I have to start from ground zero on the mount I think I will come out ok and have a great telescope. I'm interested to hear what you think about this mount and how it might be finished if it can be. My overall impression is that the OTA is unused and the mount unfinished.

Edited by cordite33 (02/27/13 12:11 AM)


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cordite33
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5702765 - 02/27/13 12:14 AM

One more thing. The tube is heavy duty and no lightweight. But since I live in an area with dark skies out my backdoor, moving it around is not much of a concern.

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nirvanix
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5702966 - 02/27/13 07:18 AM

Congratulations cordite! Sounds like you got a great deal. If that mirror was made by George Clement then you did well. Actually the base looks well made, just perhaps needs a bit of sanding and varnishing.

You're going to enjoy that scope. I just came in from looking at Saturn with my 10" dob - the rings are wide open now and show themselves well.


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Mirzam
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Re: what to look for in used 10 inch Parks Dob new [Re: nirvanix]
      #5702995 - 02/27/13 07:44 AM

I'm not sure that you need the bolts, except possibly to ensure that the encoder on one side has an attachment point. Many dob mounts just drop in the tube assembly to rest on the altitude pads. You may need to incorporate a friction increasing device (something like a pad) to fine tune the resistance on the altitude movement. Use slightly thicker felt on the rings if necessary to secure the tube.

JimC


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azure1961p
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Re: what to look for in used 10 inch Parks Dob new [Re: nirvanix]
      #5703019 - 02/27/13 08:06 AM

Quote:

Quote:

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.




Oh it's no myth, and at least when Clements was there they were boastful with a ruler straight ronchi of your particular optic. They produced - reliably - excellent optics. And through a time when everyone else like MEADE were wrought with quality control gaffs. But it costs you.

The success of SYNTA for example is great optics with consistent quality control ( that I don't think ever entered a MEADE corprorate mindset even in theory) and one terrific price. PARKS charged more but they were extremely reliable. Said anotherway, you could order a custom mirror from them, a16" for example and just about bank on excellence. With SYNTA or the like I strongly strongly doubt they'd EVER consistently produce great optics that big.

I'm not saying PARKS didn't have an occasional lemon - at least when Clements was pushing glass there however it was textbook glass - and you could talk to your personal optician over the phone. True at prices that are staggeringly higher than the imports but they were reliable as rocks on quality.

Pete


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azure1961p
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5703025 - 02/27/13 08:10 AM

Quote:

Certificate. Signed George ???




George Clements lol - you got a gem buddy!!!! I don't know if he did all there mirrors over the life of the company but he made consistently great mirrors. I'd be a little shocked if you had mediocre optics.

They weren't cheap but he made some great sets.

Pete


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Jon Isaacs
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5703064 - 02/27/13 08:44 AM

Quote:

So I am a happy camper. Even if I have to start from ground zero on the mount I think I will come out ok and have a great telescope. I'm interested to hear what you think about this mount and how it might be finished if it can be. My overall impression is that the OTA is unused and the mount unfinished.






My concern was the mount, that it would be something of a project scope which it seems to be. But with the right attitude project scopes can be wonderful experiences and I can tell you are going to have a great time with this scope. It's got personality and you are going to make it work.

Looking at the base, it is not immediately clear why it is not stable. There are some basic things going on, tall mounts are less stable, it's a relatively heavy scope on a tall mount. I am assuming that the plywood is 3/4 inch. The front cross piece is rather low, that helps stiffen tall side boards. There is a lot of wood cut away up high... It might be that if you doubled the side boards it would stiffen up nicely. Doubling the thickness increases the stiffness by a factor of 8 inch bending. That would be an easy fix, just cut pieces to match, screw, bolt, glue the two together.

I would use it as it is, get to know it as it is, try to identify the problem areas and then come up with an integrated solution. If your rebuilt the base or built a new base, you could incorporate large altitude bearings which would lower the mount and provide smoother action.

Looks like a fun project to me...

Jon


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KerryR
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Re: what to look for in used 10 inch Parks Dob new [Re: Jon Isaacs]
      #5703168 - 02/27/13 10:12 AM

I think you did very well. You probably have first rate optics in a very nice tube. Everything else can be fixed.

I think the side bolts serve 2 purposes. As others have mentioned, the encoder side is probably necessary to turn the encoder with the tube in altitude. Both sides can probably be tightened (with an appropriately sized bolt) to squeeze the pads on the sides of the rocker against the laminate sides of the alt trunions to control alt friction.

Regarding the finder, from Parks' website:
"8 x 50 R.A. Polar Finderscope
Eight power, 50mm Right-Angled Finderscope. With illuminated polar reticle for accurate alignment based on the culmination of Polaris/date and time."

I assume this is aimed at equatorial mounting, wherein an offset from Polaris to true north is necessary for more accurate tracking. It probably has indexing in the image of the reticle for time/date and off-set cross hairs or an offset circle relative to centered cross hairs. It probably also provides a mirror-reversed (and upside down) image, which you might find trying when star hopping (I certainly do). While the push-to (if it works) should reduce your need for hopping, there will probably still be times when hopping is preferable.


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nirvanix
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Re: what to look for in used 10 inch Parks Dob new [Re: azure1961p]
      #5703238 - 02/27/13 10:46 AM

Quote:

It's no myth, and at least when Clements was there they were boastful with a ruler straight ronchi of your particular optic. They produced - reliably - excellent optics. And through a time when everyone else like MEADE were wrought with quality control gaffs. But it costs you.

The success of SYNTA for example is great optics with consistent quality control ( that I don't think ever entered a MEADE corprorate mindset even in theory) and one terrific price. PARKS charged more but they were extremely reliable. Said anotherway, you could order a custom mirror from them, a16" for example and just about bank on excellence. With SYNTA or the like I strongly strongly doubt they'd EVER consistently produce great optics that big.

I'm not saying PARKS didn't have an occasional lemon - at least when Clements was pushing glass there however it was textbook glass - and you could talk to your personal optician over the phone. True at prices that are staggeringly higher than the imports but they were reliable as rocks on quality.

Pete




The myth is in the assertion about a Chinese mass-produced mirror being worse than a Parks mirror. Unless you're comparing two individual mirrors with interferograms then your myth making. I have a 10" GSO mirror from 2005 that is essentially perfect which means that at least one very good mirror maker was at GSO back then. Last night in good seeing pushed the scope to 416x with no image breakdown and was rewarded with detail inside the GRS, 5 Saturnians moons and flashes of the Enke division.

I'm happy for cordite and I'm sure he got a great scope but that has nothing to do with my scope or any other Orion, Skywatcher, Zhummell owners scope right?


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cordite33
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Re: what to look for in used 10 inch Parks Dob new [Re: Mirzam]
      #5703310 - 02/27/13 11:25 AM

Quote:

I'm not sure that you need the bolts, except possibly to ensure that the encoder on one side has an attachment point. Many dob mounts just drop in the tube assembly to rest on the altitude pads. You may need to incorporate a friction increasing device (something like a pad) to fine tune the resistance on the altitude movement. Use slightly thicker felt on the rings if necessary to secure the tube.

JimC




My impression last night was that the tube doesn't want to set in the mount squarely on the friction surfaces. The ears on the base (is that a technical optical term?) tend to spread out and the scope wants to fall down between them. So I think it at least needs a bolt on each side to secure it and hopefully get all the surfaces to meet squarely.

Thanks to everyone for your comments! I am anxious to get it up and running. Need to get some collimation tools and haunt the eyepiece forum!
Unfortunately I have to be gone the next two weeks so further investigation will have to wait a while.

Edited by cordite33 (02/27/13 03:03 PM)


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KerryR
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5703336 - 02/27/13 11:37 AM

Quote:

Quote:

I'm not sure that you need the bolts, except possibly to ensure that the encoder on one side has an attachment point. Many dob mounts just drop in the tube assembly to rest on the altitude pads. You may need to incorporate a friction increasing device (something like a pad) to fine tune the resistance on the altitude movement. Use slightly thicker felt on the rings if necessary to secure the tube.

JimC




My impression last night was that the tube doesn't want to set in the mount squarely on the friction surfaces. The ears on the mount (is that a technical optical term?) tend to spread out and the scope wants to fall down between them. So I think it at least needs a bolt on each side to secure it and hopefully get all the surfaces to meet squarely.

Thanks to everyone for your comments! I am anxious to get it up and running. Need to get some collimation tools and haunt the eyepiece forum!
Unfortunately I have to be gone the next two weeks so further investigation will have to wait a while.




Well, that IS a problem. The altitude trunions MUST sit firmly on their pads. It should be possible to shim the pads upward so that the full weight of the scope is resting on them, yet allow the bolt holes to stay in alignment.

If the sides of the rocker are so flexible that they want to spread apart, that's a bad sign for the rigidity of the rocker box. You'll know pretty quickly if things wiggle so much when focusing that you can't see the exact point of best focus, or if it takes more than 2-3 seconds to stop wiggling after focusing or guiding. Hopefully that won't be the case.


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catboat
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5703358 - 02/27/13 11:52 AM

Cordite,
Congratulations. That's a fine looking OTA -- heavy, I'm sure, but it looks very serviceable. So does the mount. Nice RA finder too.

Here's a thread that mentions George Clement from when he was at Optical Craftsman. See the posts from "lhatten".

about George Clement

I have a Parks Clement-inscribed 6" f/8 mirror. I can't attest to the quality because I haven't yet built an OTA around it. But Clement had a good reputation.

Enjoy that 10".


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cordite33
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Re: what to look for in used 10 inch Parks Dob new [Re: catboat]
      #5703675 - 02/27/13 03:03 PM

So we are leaving on vacation as soon as my wife gets home from work. I have a list of things to do by then like take the dogs to the kennel and pack my suitcase. Instead I find myself at the hardware store looking at knobs and bolts.

I came back with a couple of nice black knobs and quarter inch bolts of the right length and some washers. As I have a chance to study this in the daylight I see better how it is supposed to work. My bolts snugged things up nicely. Not yet were it needs to be but I'm starting to see some possibilities here.

I mentioned earlier that the heavy tube slips in the rings when vertical. Looks like all of the tightening adjustment is about used up so I'm thinking some extra shimming material may be needed. Looks like there is already a bit of felt like material in there already. Any ideas on something that will provide a good grip and not mar the tube?
The more I look at it the more I like those rings. I can adjust the tube to compensate for a heavy eyepiece or rotate the finder and eyepiece to a comfortable position. Just need to get it to hold rock solid.

Guess I better go pack my suitcase...


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catboat
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Re: what to look for in used 10 inch Parks Dob new [Re: cordite33]
      #5703694 - 02/27/13 03:19 PM

For lining your tube rings, felt is traditional. You may be able to find thicker felt than what's on there now. Cork works well -- available in different thicknesses from craft stores. The loopy side of velcro also works well if it's thick enough for this situation.

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Binojunky
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Re: what to look for in used 10 inch Parks Dob new [Re: catboat]
      #5703802 - 02/27/13 04:24 PM

I eat large portions of "Humble Pie", looks like its a good un,DA.

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Aircoffee
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Re: what to look for in used 10 inch Parks Dob new [Re: Binojunky]
      #5803783 - 04/17/13 12:25 AM

I hope you have fun with that "Clement" mirror. I have a Parks superior mount 10" F6 newt. that George made the mirror for. Just had is recoated and the test confirmed my amatuer opinion, an outstanding mirror. Hope your mirror is the same.

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