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Equipment Discussions >> Eyepieces

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Jon Isaacs
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Help Me Find a Finder Eyepiece new [Re: Sarkikos]
      #5623876 - 01/15/13 06:46 AM

Quote:

IME, there are a number of problems involved with mounting Newts on GEMs: an 8" or larger Newt on a GEM can be a bear to mount and handle (6" or smaller are OK); the focuser gets itself in precarious positions (rotating rings fix the problem, but are a bother); the focuser is often too high unless the observer stands; the extra weight and cumbersomeness of a GEM makes the scope more of a chore to move and setup; the OTA can hit the legs when pointed toward zenith. A better solution to heat rising from the ground is to only set up on grass and/or put a carpet under the scope.

In general, I prefer a Dob to a three-legged Newt.


Mike




Mike:

There are problems with any scope. And to be sure, large, equatorially mounted Newtonians have more than their fair share, any time someone is considering GEM mounted Newtonian, I strongly encourage them to try observing with one first.

But design is a question of addressing the various issues... Three legged solutions are a problem, Newtonians belong on piers. Historically large Newtonians were all on piers. Rotating rings, they are a necessity but they are available...

I have both GEM mounted Newtonians and Dobsonians. Most of the time I observe with a Dobsonian but if I want the best possible planetary views, I will roll out my 12.5 inch F/6 Equatorial. It's more effort, but it's on casters, it takes about 2 minutes to roll it out and a few more to connect the power, get the fans running and do the collimation. It has rotating rings. It sits on a pier. Of course it's on a driven mount. And it requires a ladder for most objects...

It's old, from a time before Dobsonians, they did everything right so the pay off is at the eyepiece... it's the closest thing to a 12.5 inch apochromat I have ever looked through..

Jon

Edited by Jon Isaacs (01/15/13 06:47 AM)


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Sarkikos
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Help Me Find a Finder Eyepiece new [Re: Jon Isaacs]
      #5623886 - 01/15/13 07:07 AM

I mounted my first two telescopes on an Edmund pedestal GEM. They were a 4.25" f/10 and a 6" f/8. No tripod legs on the mount, so the long OTA's were unencumbered when pointing to zenith. I sold the mount back in the early '80's.

Mike


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Scanning4Comets
Markus
*****

Reged: 12/26/04

Re: Help Me Find a Finder Eyepiece new [Re: Sarkikos]
      #5623898 - 01/15/13 07:17 AM

I agree about GEM's putting the scope in all kinds of weird positions. This is where the fork mounted CAT comes into play with good positions to the telescope for every kind of orientation in the sky.

I think the fork mounted CAT is the way to go of you want tracking. If I were to get another scope with tracking, I'd buy an 11" CAT. My observing friend ,(JunoMike), has an 11" CAT and I have looked through it. Galaxies are a lot brighter than when viewing in my 10" scope, so the secondary obstruction seems to have no impact on brightness of dim objects. Bottom line is that a fork mount is better than a GEM IMO.

BTW, Nice scope JunoMike!

Now, back to the regular OP of "Help Me Find a Finder Eyepiece".

Cheers,


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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Help Me Find a Finder Eyepiece new [Re: Scanning4Comets]
      #5623907 - 01/15/13 07:30 AM Attachment (11 downloads)

Quote:


I agree about GEM's putting the scope in all kinds of weird positions. This is where the fork mounted CAT comes into play with good positions to the telescope for every kind of orientation in the sky.

I think the fork mounted CAT is the way to go of you want tracking.




CATs certainly are handy but I believe a Newtonian with top notch optics is capable of providing better views. This is the eyepiece forum so it is probably best that it not drift too much more off topic. I will just say this:

Done right, a big Newtonian on a GEM is difficult to match when it comes to the quality of the view.

Jon

Edited by Jon Isaacs (01/15/13 07:32 AM)


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MRNUTTY
Carpal Tunnel
*****

Reged: 11/22/11

Loc: Mendon, MA
Re: Help Me Find a Finder Eyepiece new [Re: Jon Isaacs]
      #5623951 - 01/15/13 08:01 AM

Beautiful scopes Jon.

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csrlice12
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Reged: 05/22/12

Loc: Denver, CO
Re: Help Me Find a Finder Eyepiece new [Re: Sarkikos]
      #5623984 - 01/15/13 08:35 AM

I'd never go the 10" on a stick route. The 4" refractor is enough for slewing around as it is. I have other means to determine wind direction without using a Newt as a windsock.....To each his own though...

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Scanning4Comets
Markus
*****

Reged: 12/26/04

Re: Help Me Find a Finder Eyepiece new [Re: csrlice12]
      #5624023 - 01/15/13 09:02 AM

Quote:

CATs certainly are handy but I believe a Newtonian with top notch optics is capable of providing better views. This is the eyepiece forum so it is probably best that it not drift too much more off topic. I will just say this:

Done right, a big Newtonian on a GEM is difficult to match when it comes to the quality of the view.

Jon




This is the eyepiece forum with pics of telescopes? The topic is "Help find me a finder eyepiece", but here you are posting pics of your telescope again. LOL!

Yea, let's try not to drift off topic Jon. We've only seen this picture a 100 times, in several different off topic posts.

Now, back to your scheduled program...


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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Help Me Find a Finder Eyepiece new [Re: csrlice12]
      #5624032 - 01/15/13 09:10 AM

Quote:

I'd never go the 10" on a stick route. The 4" refractor is enough for slewing around as it is. I have other means to determine wind direction without using a Newt as a windsock.....To each his own though...




My 12.5 inch is actually quite stable in the wind. The 100 lb OTA + 85 lbs of counterweights does have some effect.. But that said...

I do not recommend large Equatorially mounted Newtonians, particularly ones that require a ladder. There is just too much chance of being stunned by the high quality view and falling off the ladder.



I don't use it a lot but when I do...

Jon Isaacs


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Sarkikos
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Help Me Find a Finder Eyepiece new [Re: csrlice12]
      #5624084 - 01/15/13 09:49 AM

Quote:

I'd never go the 10" on a stick route. The 4" refractor is enough for slewing around as it is. I have other means to determine wind direction without using a Newt as a windsock.....To each his own though...




I would never put more than a 6" Newt on a GEM, even on a perfectly calm night. That's my preference based on my experience, even before I start to consider the wind factor. But I've observed with my 10" Dob in wind gusts as high as 25 mph. The scope did not move at all.

Mike


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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Help Me Find a Finder Eyepiece new [Re: Sarkikos]
      #5624556 - 01/15/13 02:38 PM

Quote:

Quote:

I'd never go the 10" on a stick route. The 4" refractor is enough for slewing around as it is. I have other means to determine wind direction without using a Newt as a windsock.....To each his own though...




I would never put more than a 6" Newt on a GEM, even on a perfectly calm night. That's my preference based on my experience, even before I start to consider the wind factor. But I've observed with my 10" Dob in wind gusts as high as 25 mph. The scope did not move at all.

Mike




Mike:

If I only had one 12.5 inch scope, it would not be a larger Newtonian on a GEM. Too big to easily transport, too awkward point. But I am fortunate and able to enjoy both a 12.5 inch Dobsonian and a 12.5 inch Equatorial, both have their place. I am not forced to use it but when I get the hankering to roll it out, it is a treat.

Jon


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jrbarnett
Eyepiece Hooligan
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Reged: 02/28/06

Loc: Petaluma, CA
Re: Help Me Find a Finder Eyepiece new [Re: Scanning4Comets]
      #5624618 - 01/15/13 03:10 PM

The problem with large fork mounted Cats is that you're OTA is dependent on potentially unreliable electronics...

...*cutscene*...

Dave finishes loading his camping gear and CPC-1100 into the back of his pickup truck under the shell, bids his loving wife farewell, and sets out to BoonieStar, the finest dark sky star party in the Tri-state area. Seven hours, a fill-up, drive-through fast food run and potty break later, Dave reaches the turn-off for the star party. Before him lies a rock-strewn road carving its way in the form of a narrow shelf up Deadman's Peak, the site of BoonieStar.

It is slow going, nerve-wracking work guiding the truck up the scratch that passes for a road in these parts. Hours later, Dave reaches the saddle and spies the meadow peppered with scopes as well as the big registration tent. He picks his spot, parks, and walks over to the tent, gives his name and waits while the attendant thumbs through index cards before asking him to spell his name. Apparently Dave's registration is missing! Fortunately he printed his confirmation, and heads back to the truck to fetch it. Eventually the registration snafu is sorted out and Dave heads back to his truck to set up his tent and gear as the Sun bathes the field in old gold glow as it drifts toward the borders of twilight.

Dave sets up the CPC-1100 with much grunting. He then goes to connect the battery. Battery! Oh chit! Dave forgot his power source! His observing neighbor, Bill, alerted by the stream of staccato profanities coming from Dave's direction, walks over to see what the problem is. Dave explains that he's batteryless. Bill says not to worry and loans Dave his back-up battery. Dave thanks Bill profusely and all is seemingly well...

As dusk sets in, Dave fires up the CPC, to let the GPS get a fix and to align the GOTO system using the handful of first magnitude stars that are just starting to peep out of the deepening gloom. He connects the cables to the hand controller and battery, and switches it on. NOTHING!

He checks his connections, the charge on the borrowed battery, and still nothing. His mighty fork mount is dead, dead, dead. It could have been the bumpy ride. It could be a manufacturing defect. It could be the fact that Dave left the mount outside under a cover for nearly a month last spring. But whatever the cause, the mount is kaput.

Bill saunters over in answer to a new string of profanities from Dave and asks what is wrong now. Dave explains that his robotic fork mount is dead, and laments that he won't be making any progress on his Herschel 400 project. Bill says, "I have a spare Orion Atlas mount. Can you move your OTA to that? If so, you can borrow it."

Therein revealing the problem with an OTA that is semi-permanently mated to its mount.

I never leave serious observing to scenarios that have a single point of failure such as a fork-mount dependency. Redundancy is your friend.

Regards,

Jim


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junomike
Carpal Tunnel
*****

Reged: 09/07/09

Loc: Ontario
Re: Help Me Find a Finder Eyepiece new [Re: jrbarnett]
      #5624676 - 01/15/13 03:44 PM

Jim, that's a good point, but I haven't had any issues with my NS11GPS in the 3 years I've had It. It was made in 2005 so It had lots of use before I got It.

Will It last forever? Nope, but when It finally does go beyond conventional repair, I'll de-fork he OTA and use funds from It's sale to get another ForkMount (maybe the CPC100 HD).

I don't mind the extra cost and "chance" associated with the ForkMount as the trade-off to have GOTO and Tracking in a easy viewing position is worth It....at least to me!

Mike


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Scanning4Comets
Markus
*****

Reged: 12/26/04

Re: Help Me Find a Finder Eyepiece new [Re: junomike]
      #5624714 - 01/15/13 04:03 PM

Mike,

Your scope is awesome and has never once failed us at the observing spot. It's always funny reading drama in these forums, but then again, this thread has turned from "Help me find a finder eyepiece" to, "look at my scopes everybody, or create controversy."

Cheers,


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Help Me Find a Finder Eyepiece new [Re: jrbarnett]
      #5624815 - 01/15/13 05:07 PM

Jim,

I have zero experience with a fork mount except to see others heave that over-sized paint-can of an OTA onto the top of it. But if the battery is dead or the electronics in the mount are kaput, can't the observer still move the thing by hand?

Give me a scope I can push by hand and a decent finder and I'm all set. Otherwise that super-golly gee-whiz gizmo is just a disaster waiting to happen.

Mike


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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Help Me Find a Finder Eyepiece new [Re: jrbarnett]
      #5625261 - 01/15/13 09:47 PM

Quote:

The problem with large fork mounted Cats is that you're OTA is dependent on potentially unreliable electronics...




There were three guys with a 12 inch LX-200 GPS that used to share a "secret spot" with my wife and I. I had my 12.5 inch Dob which was pretty reliable, never had any electronics issues...

On more than one occasion, they would set up the LX-200, that took quite a while, then I would hear some wild slewing of the motors, some discussion, some more wild slewing of the motors. I would wander over, the controller was giving them an error. They would tear it down..

And they then strolled over my way...

Their backup was me...

Jon


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Sarkikos
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: Help Me Find a Finder Eyepiece new [Re: Jon Isaacs]
      #5625297 - 01/15/13 10:07 PM

IME, there is no more irritating sound than a coffee-grinder goto mount at a dark site. I am delighted that in the last two years, all of the coffee grinders seem to have given up or gone elsewhere. The Dob Masters have taken the field. Huzzah!


Mike


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csrlice12
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Reged: 05/22/12

Loc: Denver, CO
Re: Help Me Find a Finder Eyepiece new [Re: Jon Isaacs]
      #5625933 - 01/16/13 10:25 AM

Quote:

Quote:

The problem with large fork mounted Cats is that you're OTA is dependent on potentially unreliable electronics...




There were three guys with a 12 inch LX-200 GPS that used to share a "secret spot" with my wife and I. I had my 12.5 inch Dob which was pretty reliable, never had any electronics issues...

On more than one occasion, they would set up the LX-200, that took quite a while, then I would hear some wild slewing of the motors, some discussion, some more wild slewing of the motors. I would wander over, the controller was giving them an error. They would tear it down..

And they then strolled over my way...

Their backup was me...

Jon




Wow, a 12.5" backup scope.......


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