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If you had a $5000.00 budget.

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#76 Jethro7

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Posted 13 October 2020 - 02:11 PM

Yes im liking the 102ed F-11 especially at the special open box price of $500 shipped.

Funny you mentioned a 6 inch F-15; 6 years ago i ordered a D&G 6 inch F-12 cell. Finished the ota, still waiting for the lens. Found a 6 inch F-10 istar r-30 un-used and 2 days after buying the istar i got a message that the D&G was almost ready. One way or another i will have a long achro before too far into the future. Ended up getting the APM 152ed while waiting for the D&G.

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Hello DRD715,

Those long focal length Achros are amazing I did not understand till I owned a couple why they have such a cult following. I do now.

 

HAPPY SKIES TO YOU AND KEEP LOOKING UP Jethro



#77 CounterWeight

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Posted 13 October 2020 - 02:16 PM

I'd spend about $2k of it on a small refractor and mount.  I'd spend the rest on the largest Dob I could reasonably use!


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#78 Jethro7

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Posted 13 October 2020 - 02:17 PM

Hi Jethro,

 

I am certainly one of the people who considers the TEC 140ED to be "the perfect scope" (whatever that really means wink.png), and have said so here on CN. My rationale? It is as optically perfect as any premium scope currently available, the oil spaced objective cools/settles down surprisingly fast, it has an unbeatable 3.5" focuser, at 19 pounds clean it weighs less than many popular premium Apos with less aperture, they come up fairly frequently in the secondary market at pretty reasonable prices (for a high end Apo), due to its weight and length it is easily mounted on Atlas/G-11/CGEM class mounts, and it has a lots of aftermarket supports for upgrades and add-ons. Easy on the eye, comparatively easy on the wallet, and with an extra bit of aperture to help get whatever observing or imaging task you want done...what's not to like? Here's hoping you find what you are looking for!

 

attachicon.gifIMG_7265sc.jpg

 

Clear Skies,

Brian snoopy2.gif

Hello Brian,

It is pretty simple, it's the reason that the TEC 140 is the scope you tend to use the most.

 

HAPPY SKIES TO YOU AND KEEP LOOKING UP Jethro

 

P.S. That's a nice setup indeed. I am half way there with being gifted a C8 Edge HD today. 


Edited by Jethro7, 13 October 2020 - 10:43 PM.

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#79 Jon Isaacs

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Posted 13 October 2020 - 03:24 PM

I assure you, Jon, quality is never an abstract characteristic.  Never.  No matter which metric you may choose to measure it; or benchmark used to define it.

 

I am a little surprised we're even having this argument as we seem to be in somewhat violent agreement in that its all about priorities.

 

You are reading into this a bit.  Never said a single characteristic defines quality.  Rather, what I said/implied is this:  its the sum of the priorities driven by a subjective value system.  Yours are different then mine - that does not make it inferior/superior.  It just makes it different.  This is a straw man debate.

 

In my opinion, far off-axis sharpness is over-rated unless one is choosing to purchase an instrument for photography.  I have never once heard anyone say that "...wow, the center is mush; but my God the off axis image is impeccably sharp and contrasty."   What is not opinion is this:  if the lens is not high quality it won't matter what the off axis performance is to the visual observer.

 

To state the obvious, refractors have limited aperture.  To this end, I want the best optics possible so the performance of the lens is only limited by its aperture.   

 

I've observed with, and tested a couple of NP127's, TEC140ED's and TSA120's.  So, at least I come by my conclusions honestly.   And, based on this, I made my recommendation as it pertains to the $5k budget.

 

Regarding the Don Bruns' experiment - I read the thread when it was active.  But, really, he had no choice but to use an NP101 (or similar) regardless of its overall optical quality.  His primary needs in a telescope were FOV and focal ratio for this experiment, not optical quality.  Though I am sure he wanted a diffraction limited OTA and the NP101 certainly provided that.

 

Anyway, that's how I see it.

 

We clearly have different attitudes towards what quality means.

 

-  Regarding field flatness: The center being mush, while the edge is sharp, that's not a flat field, that's what you can get with a short focal length doublet or triplet viewing at low powers wide fields.  

 

- I don't think in terms of what 4 inch (or whatever) telescope provides the best views of a particular object, I think in terms of what telescope provides the best view, aperture is one of the many variables. 

 

- Optical quality is suitability of a particular telescope system for a particular task.  Don Bruns used an NP-101 because it had the particular set of optical characteristics/qualities that fit his needs. 

 

- Quality depends on the job at hand, in that sense it's not abstract, it's not subjective. It's difficult to argue that the NP-127 will not provide the most perfect 3.65 degree star field of any of the 5 inch scopes under discussion. 

 

On the other hand, if one is looking for the sharpest, most contrasty view of Jupiter, there are other 5 inch refractors that would very likely be a better choice.

 

But in my world, a 5 inch refractor is not the best choice for achieving the sharpest, most contrasty views of Jupiter. 

 

Jon


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#80 peleuba

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Posted 13 October 2020 - 04:24 PM

We clearly have different attitudes towards what quality means.

 

lol.gif   Indeed we do.  Precisely.

 

Quality, does not vary depending on the "job at hand".    

 

You are confusing  term "quality" with the adage "right tool for the right job".    These are tangentially related concepts, but fundamentally not one in the same.

 

In any event, this is about answering Phillip's question.  I stand by what I said based on this being the Refractor forum and my own use of several samples of the three scopes I mentioned (NP127, TSA120, TEC140ED).  Have you used any of the three?  If not, it sort of a conceptual argument rather then one based on real-world experience.  Additionally, I can't be too far off the mark as several others in the thread have recommended the same instruments. 

 

 

<<But in my world, a 5 inch refractor is not the best choice for achieving the sharpest, most contrasty views of Jupiter.>>

 

We do agree on this point - but this is the refractor forum and I assume Phillip wants a refractor...


Edited by peleuba, 13 October 2020 - 04:30 PM.

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#81 CHASLX200

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Posted 13 October 2020 - 06:12 PM

We clearly have different attitudes towards what quality means.

 

-  Regarding field flatness: The center being mush, while the edge is sharp, that's not a flat field, that's what you can get with a short focal length doublet or triplet viewing at low powers wide fields.  

 

- I don't think in terms of what 4 inch (or whatever) telescope provides the best views of a particular object, I think in terms of what telescope provides the best view, aperture is one of the many variables. 

 

- Optical quality is suitability of a particular telescope system for a particular task.  Don Bruns used an NP-101 because it had the particular set of optical characteristics/qualities that fit his needs. 

 

- Quality depends on the job at hand, in that sense it's not abstract, it's not subjective. It's difficult to argue that the NP-127 will not provide the most perfect 3.65 degree star field of any of the 5 inch scopes under discussion. 

 

On the other hand, if one is looking for the sharpest, most contrasty view of Jupiter, there are other 5 inch refractors that would very likely be a better choice.

 

But in my world, a 5 inch refractor is not the best choice for achieving the sharpest, most contrasty views of Jupiter. 

 

Jon

I hate FC as much as coma when it comes to sweeping. Seeing out of focus stars coming and going in the FOV.  Can't live with it.  So super fast fracts are out and at least a Paracorr helps with Newts faster than F/5.6,  The sub F/5 drives nuts thanks to shallow focus so no super Fast Newts as well. 



#82 Jon Isaacs

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Posted 13 October 2020 - 06:27 PM

Quality, does not vary depending on the "job at hand".   

 

You are confusing  term "quality" with the adage "right tool for the right job".    These are tangentially related concepts, but fundamentally not one in the same.

 

 

A quality knife has different characteristics than a quality hammer.

 

A quality wide field refractor has different characteristics that a quality planetary refractor.

 

I was a research engineer who measured the material properties of a great many materials. These included dynamic fracture toughness of the ISS shell, the concrete in German nuclear containment in dynamic tension, the ballistic properties of ceramic armor reinforced with various composites, the dynamic properties of the steel used in navy ships.

 

A quality material does depend on the application, just as the desirable charactertics of a quality optic depends on the application.  

 

Jon


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#83 sw196060

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Posted 13 October 2020 - 06:46 PM

A nice dob!


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#84 BillP

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Posted 13 October 2020 - 08:04 PM

If I had a 102 Apo and a C8 Edge like you do, and was looking for something more to give me different capability, then the 1st choice would be a NV setup, and specifically one for naked eye, 2x, 3x viewing.  So not something to put onto a scope necessarily.  Sure you can adapt it for that but first and foremost would get it to observe without a telescope.

 

If not that, and you wanted more defined views than you are getting with you C8, then I would opt for something more around 130mm Apo.  Yes 140 and 152 is nice, but they are big enough and take enough time to acclimate to temps than you will probably take them out less.  A 130 is IMO at the tipping point so still enjoyable bright views and ergonomics still nice.  The new AT-125 EDL is intriguing IMO as a doublet so will cool faster and easier maintenance over a triplet (if at some point you do have to much with the objective). 

 

https://www.astronom...-8-doublet.html

 

But in the end, I think the NV will be the more new and interesting viewing experience.  So would get that first, then later get the 125 as it is much less expensive


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#85 Jethro7

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Posted 13 October 2020 - 10:46 PM

Stellarvue 140 for both the budget spend and the one to keep smile.gif

Hello, Jon.

I keep seeing good stuff on Stellarvue upper end refractors.

 

HAPPY SKIES TO YOU AND KEEP LOOKING UP Jethro.


Edited by Jethro7, 13 October 2020 - 11:16 PM.


#86 rkelley8493

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Posted 13 October 2020 - 10:55 PM

I keep seeing good stuff on Stellarvue upper end refractors.

I've been very pleased with my Stellarvue SVA130T [the predecessor to the SVX-series]. I've had it for almost two years and have enjoyed every second out observing with it. I believe there's still one in stock at High Point Scientific, but it comes as a kit with Stellarvue Optimus eyepieces and a mirror diagonal. It's under your budget, and you could probably flip the eyepieces for a profit if you don't need them.

 

https://www.highpoin...sva130t-25sv-vs

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Edited by rkelley8493, 13 October 2020 - 10:57 PM.

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#87 bobhen

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Posted 14 October 2020 - 06:19 AM

Hello, Jon.

I keep seeing good stuff on Stellarvue upper end refractors.

 

HAPPY SKIES TO YOU AND KEEP LOOKING UP Jethro.

The SV 140 lists for $6,500 ( over your $5,000 budget) and since this is a new model there are no used options. The 130 lists for $5,000.

 

Bob



#88 peleuba

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Posted 14 October 2020 - 10:08 AM

A quality knife has different characteristics than a quality hammer.

 

A quality wide field refractor has different characteristics that a quality planetary refractor.

 

 

 

 

I don't think we're far apart, but allow me to make this final point...   

 

To use your example - I can have a super high quality, very precisely machined and perfectly balanced hammer.  But it can't cut anything.   Let's say your knife is mass produced, imported, and even in a low quality, dulled state will cut much better then my hammer.  To me, it does not mean its higher quality then the hammer, its just means its the "right tool for job".  

 

To me, quality is an absolute.  Its tangible and describes precision of purpose, manufacture and result for its intended use.  Just because my hammer cannot cut anything, does not mean its lower quality then your knife.  It means its the wrong tool for the job.

 

So, how many angels do dance on the head of a pin?  smile.gif

 

So, Jethro, what are you gonna do with all of this advice?


Edited by peleuba, 14 October 2020 - 12:09 PM.


#89 Jethro7

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Posted 14 October 2020 - 10:21 AM

I'd spend about $2k of it on a small refractor and mount.  I'd spend the rest on the largest Dob I could reasonably use!

Hello CW 

Have that area,covered already.

Thank you for your post

HAPPY SKIES AND KEEP LOOKING UP Jethro



#90 25585

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Posted 14 October 2020 - 12:52 PM

For NV & a 140mm, what about the APM doublet? With the spare change you could get a better NV device, more filters etc.


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#91 bobhen

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Posted 14 October 2020 - 01:16 PM

For NV & a 140mm, what about the APM doublet? With the spare change you could get a better NV device, more filters etc.

With a refractor, and if Night Vision observing is the ONLY consideration, you don’t absolutely need an apo. A 120 F5 or 150mm F5 achromat will work really well and save you a ton of money – just like these fast achomats work really well for regular, low power, wide field observing. The APM 140 will, of course, work well with NV but why spend the money for just NV observing?

 

If you want to do NV AND high power lunar/planetary observing, the high quality triplets from TEC, TAK, CFF etc. will do better than the APM 140 F7 doublet. Not that the APM140 will be bad (and it might be good enough depending on the observer) it's just that the other triplets will be a notch or two up.

 

Bob



#92 csrlice12

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Posted 15 October 2020 - 09:52 AM

Looking at your current equipment list....that trip to Australia would be even more tempting.



#93 aa6ww

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Posted 15 October 2020 - 10:22 AM

Im good with my APM 152 and my new CGEMII using my Losmandy G11 Tripod. All I need are clear skies and I can take care of the rest.

 

...Ralph



#94 aa6ww

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Posted 15 October 2020 - 10:22 AM

Im good with my APM 152 and my new CGEMII using my Losmandy G11 Tripod. All I need are clear skies and I can take care of the rest.

 

...Ralph

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#95 Jethro7

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Posted 15 October 2020 - 09:42 PM

Im good with my APM 152 and my new CGEMII using my Losmandy G11 Tripod. All I need are clear skies and I can take care of the rest.

 

...Ralph

Hello Ralph,

Nice set up. And you have my favorite eyepiece. I could use some Good Seeing conditions here lately. Lots of upper atmospheric turbulence here, the views look like you are viewing the Planets in a pool of wind swept water. Oh well, I will have to be patient. 

 

HAPPY SKIES TO YOU AND KEEP LOOKING UP Jethro



#96 TareqPhoto

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Posted 18 October 2020 - 02:16 AM

I wish to have $5000, so i can add or save more and buy one of those AP/TEC/Tak scopes around.


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#97 csrlice12

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Posted 18 October 2020 - 10:43 AM

If I had $5000, my wife would come up with some home project to spend it on....


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#98 Jethro7

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Posted 18 October 2020 - 12:14 PM

I wish to have $5000, so i can add or save more and buy one of those AP/TEC/Tak scopes around.

Hello TareqPhoto,

Just feed the pig every chance you can. One easy way to do it,  never spend a Dollar Bill till your ready to, feed it to the pig. It adds up quick. I will not support a hobby with credit, and that will keep me out of trouble. It is probably unamerican of me to not carry a Debt more than I can pay out of pocket but that's me. 

 

HAPPY SKIES AND KEEP LOOKING UP. Jethro


Edited by Jethro7, 18 October 2020 - 02:46 PM.

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#99 TareqPhoto

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Posted 18 October 2020 - 01:20 PM

Hello TareqPhoto,

I just feed the pig every chance you can. One easy way to do it,  never spend a Dollar Bill till your ready to, feed it to the pig. It adds up quick. I will not support a hobby with credit, and that will keep me out of trouble. It is probably unamerican of me to not carry a Debt more than I can pay out of pocket but that's me. 

 

HAPPY SKIES AND KEEP LOOKING UP. Jethro

Well said, thanks!



#100 gnowellsct

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Posted 19 October 2020 - 07:33 PM

I'd take my existing scopes on a vacation to Australia....


That's a good idea. But short of Australia take one of your existing scopes to New Mexico or Colorado or somewhere like that. Unless you already live there of course.


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