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Stellarvue 115 Triplet vs NP-101

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#1 chaoscosmos

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Posted 16 February 2013 - 03:51 PM

Apropos to some of the comments in the discussion 'Aperture isn't Everything'... I'm wondering if since the vast majority of my viewing will be in semi-light polluted skies, if I should focus on as large an aperture scope as I can afford. The idea being that, given my usual viewing environment, I would use it for planetary viewing primarily and do what I could with it for deep sky. So I'm wondering that given the above, if something like the SV 115 would be a better choice for me than the NP-101. Or is the NP-101 versatile enough that it might make up in my occasional dark sky opportunities what it might lose viewing from my backyard?

If you can throw light on the topic or offer your 2 cents, I appreciate it.
I'm open to alternative suggestions to the Stellarvue.

#2 la200o

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Posted 16 February 2013 - 04:39 PM

Both fine scopes. The NP 101 will give superb wide-field views as well as take high power very well.

Bill

#3 NHRob

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Posted 16 February 2013 - 05:29 PM

TSA-120??

#4 Scott in NC

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Posted 16 February 2013 - 07:14 PM

I realize that I'm just pointing out the obvious, but the 115mm scope will gather 29.6% more light than the 101mm scope. And with a 31T5 Nagler, you can still get a 3.15 degree TFOV with a 115mm f/7 scope. Admittedly that's not as wide a field as the NP101 will give you, but it's still a pretty wide field. The truth, though, is that they're both great scopes. I can't imagine you'd be unhappy with either one of them.

#5 SteveG

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Posted 16 February 2013 - 08:04 PM

I'm in a similar situation, and can strongly recommend the 115mm scope. Actually, I recommend a 120mm ed refractor such as the Eon 120 or similar.

#6 Jon Isaacs

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Posted 17 February 2013 - 11:14 AM

If you can throw light on the topic or offer your 2 cents, I appreciate it.



This is the way I look at it:

A $500, 10 inch GSO Dobsonian seriously outperforms either of these scopes at higher magnifications. If it fits in the field of view of the 10 inch Dob, the Dob is just so superior. Where the 115mm has a 13% advantage in resolution and 28% light gathering advantage over the NP-101, a 10 inch Dob has more than twice the resolving power and gathers about 4 times as much light, these are numbers that indicate huge differences at the eyepiece.

At the eyepiece, looking at the planets, looking at double stars, I'll take my 10 inch GSO Dob over my NP-101 if there is time for the Newtonian to cool. On those dark sky trips, a 10 inch Dob will do the number on the refractors.

The thing about the NP-101, it does the things that refractors do best, best... There is no field curvature in the widefields, there is no chromatic aberration at the highest magnifications. With it's 540mm focal length, it's like an 80mm in terms of field of view but it's a 4 inch. The 115mm is a small scope that is quite long but still small in terms of aperture. You can only do so much with 101.6mm or 115mm.

I recommend to things:

- Consider a second scope, that $500 Dob is an incredible value and a powerful tool. Point it at M13 or the Orion nebula.. it packs some punch.

- The StellarVue 115 is about $3200, it's a triplet but from what I can find out, apparently not an FPL-53 triplet, the FPL-53 costs more and provides the possibility of better color correction. I would swing my gaze over towards Astro-Tech, two scopes, the Astro-Tech 111 EDT and the Astro-Tech 106.

The Astro-Tech 111 EDT is very similar in aperture to the SV-115, it may even be manufactured by the same manufacturer as the SV-115. You are giving up very little aperture and saving a lot of money. The AT-106 uses the better FPL-53 glass, costs more than the 111EDT but still considerably less than the 115.

These are all good scopes. When you are looking at the difference between the NP-101 and the others, you are looking at a scope that takes it that last little bit, both mechanically and optically, that costs so much. It probably takes a trained eye to notice at first glance that at low powers with widefield eyepieces, the stars are round and sharp at the edge of the field in the NP-101. In the other scopes, there is field curvature to be seen, the views are still totally amazing...

If I didn't have an NP-101, I would probably now own a AT-106...

jon

#7 Scott in NC

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Posted 17 February 2013 - 12:51 PM

Post deleted by Scott in NC (edited to correct some misinformation that I had mistakenly posted!) :foreheadslap:

#8 Rich V.

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Posted 17 February 2013 - 01:15 PM

In searching, I don't see where Vic has ever said that FPL-53 is used in the 115T. He'd say it if it was used; he has no hesitation claiming that glass is used in some of his other offerings.

In a SV group post from 2008, he hedges around saying he uses FPL-53 and denies using FPL-51:

"The optical design of the SV115T is as good as we make it. As
always, we will be prodded to disclose glass types. People will want
to know if it is FPL-53 as if this is the only good glass on the
market. While Ohara FPL53 is certainly better than Ohara FPL-51,
there are other excellent glass types made by Schott and others. The
fact is, the best optical systems we have ever produced are the LZOS
Advanced Optical Systems using OK4 Russian glass. These lenses
outperform our other lenses using FPL-53. This should explode the
myth that a telescope absolutely must have FPL-53 to be the best.
Certainly FPL-53 is excellent, but it is not the only game in town.

I think some people ask this question wanting to make sure it is not
the less expensive Ohara FPL-51. That is valid. I will state that the
115T does not use FPL-51. Bottom line is, the SV115T provides a color
free, perfect star test. The correction is as good as we can make it.
With these facts clearly stated, only the competition wants to know
specific glass types. We will clearly state how this telescope
performs but we will not give up three years of R+D just to satisfy
the nay sayers. We will let the 115 stand on its own merits. I am
making this post as a reference as I will be asked this question over
and over again."

A Schott ED glass combo of ZKN7/FK51/ZKN7 would be a good guess; FK51 has an Abbe number about halfway between FPL-51 and FPL-52 and this triplet combo can provide a Strehl of .95 or greater to meet SV's premium apo specs.

See:

Telescope Optics.net reference 1
Telescope Optics.net reference 2

Rich

#9 johnnyha

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Posted 17 February 2013 - 01:24 PM

In searching, I don't see where Vic has ever said he uses FPL-53 in the 115T.


He would never use it, since he doesn't make telescopes. He may have been extremely instrumental in selecting it from a catalog however... :question: ;)

#10 Rich V.

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Posted 17 February 2013 - 01:34 PM

In searching, I don't see where Vic has ever said he uses FPL-53 in the 115T.


He would never use it, since he doesn't make telescopes. He may have been extremely instrumental in selecting it from a catalog however... ;)


Edited to remove that ambiguity. ;) Making the assumption that SV scopes are entirely rebrands may be going a bit far however...

Rich

#11 johnnyha

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Posted 17 February 2013 - 01:40 PM

:grin:
I know that Vic does some QC and tries to weed out the lemons, I didn't know it went any further than that. If so I certainly apologize. I was under the impression that versions of the SV scopes could also be purchased under different brand names from different vendors, so SV is similar to say Explore Scientific or Astro Tech... :question:

#12 chaoscosmos

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Posted 17 February 2013 - 01:51 PM

Not seeing much on the net on the Astro-Tech 106, with regard to personal experiences... And if I'm reading this correctly, you guys are saying that SV, AT, and ES are in many cases essentially the same scopes?

#13 johnnyha

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Posted 17 February 2013 - 01:52 PM

And if I'm reading this correctly, you guys are saying that SV, AT, and ES are in many cases essentially the same scopes?


Not necessarily but I had assumed they were all made by one of the two Chinese telescope makers Synta or GSO so, if not I apologize, maybe someone can jump in and clear it up...?

#14 Scott in NC

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Posted 17 February 2013 - 01:53 PM

Well, now that you mention it, I really thought that I had read in the SV115T product description on the stellarvue.com website that that scope had an ED element made of FPL-53. But if that description was ever there, it's gone now. So I may have been mistaken, and may have confused this with another SV triplet apo scope like the SV80ST and the SV90T. There's currently no mention of glass types used for the SV105T, SV115T, and SV130T. I'll edit my post above, as I don't want to spread any misinformation.

#15 microstar

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Posted 17 February 2013 - 02:08 PM

I think there is more to a good refractor than FPL-53 or who makes it. The mating glass is as important. The scope makers will make objective elements to whatever specification the purchaser desires. I like that Vic star-tests every scope and sends back those that don't meet spec. I am willing to pay a bit more for that and a for a well-executed design that I have confidence in. I'd be disappointed if with SV it's just a bit of QC on mass-produced scopes, but my understanding is that it is more than that.
...Keith

#16 RGM

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Posted 17 February 2013 - 02:25 PM

As a side note, you should not be asking Canadians for their 2 cents worth. We got rid of the penny on the 4th of Feb. Now you have ask for our nickel worth.

#17 LivingNDixie

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Posted 17 February 2013 - 03:46 PM

Not seeing much on the net on the Astro-Tech 106, with regard to personal experiences... And if I'm reading this correctly, you guys are saying that SV, AT, and ES are in many cases essentially the same scopes?


That would be reading it correctly. SV has changed some minor things in the past on some scopes, but in the end there are only so many scope makers so the chances are you can buy the same product from another company... usually for less money. When you buy a new SV you are basically paying a premium for the owner of the company to basically "star test" and then repackage it for you, he does not send you any paperwork to you telling you how your scope tested. I can understand why, if one scope tested better and your buddy got it, you might be upset. However if he sent the paperwork out with the scope and said what his standard was that a scope had to pass by, he could get around that. In the end I don't see any value being added to the product without the paperwork.

In the end only you can decide if that is worth it to you. If it were me I would just go get a used Tak or Televue before paying that premium. If I was picking between a new Televue and a new Stellarvue in the four inch range, I would probably go with the Televue. However I am more of a Tak guy and if I were in your shoes I would look for a used FS102, but that is after the experience of owning a Tak FS78.

#18 Rich V.

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Posted 17 February 2013 - 04:17 PM

To be fair, SV may just test and "repackage" the lower to mid range scopes but their premium scopes can be a mix-and-match build from components from various sources.

In the past they have built up scopes with Russian LZOS and LOMO objectives with USA Starlight focusers and their own CNC machined clamshells, flanges and extensions. I know my SV80S from 2007 is one of these scopes. There was no generic scope with those specs being produced.

I think this can be applied to their current premium scopes as well. Just because SV may not figure the optics, the scopes are built to a spec with parts sourced from a number of suppliers and meet a very high standard just the same.

My TMB 130 is a "built" scope with an objective from one source, a focuser from another with tube and rings from another. The same applies to the APM/LZOS scopes; that doesn't make them a "repackage" does it?

Sweeping statements should be backed up with evidence. This is the age of science based on evidence, not heresay, you know!

Rich

#19 Yu Gu

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Posted 17 February 2013 - 04:44 PM

No, it doesn't use the CHEAP FPL-51. It use the chinese equivalent FK-61. I wish I am that good at implying things...
:tonofbricks:

#20 johnnyha

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Posted 17 February 2013 - 04:46 PM

Yes my apologies then, if SV does use LZOS and LOMO obviously that sets them apart from generic. :cool:

#21 RTLR 12

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Posted 17 February 2013 - 05:10 PM

I don't think that all of the SV115Ts are all using the same glass. I don't think any of them use FPL 53 or FPL 51, but I like many people, don't know what glass is used. I think it could be from one of a number of glass makers. I can say one thing about my SV115T20 and that is that it is far from being "color free...".

Stan

#22 Scott in NC

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Posted 17 February 2013 - 05:25 PM

Yes my apologies then, if SV does use LZOS and LOMO obviously that sets them apart from generic. :cool:


From the information readily available on the web (i.e., from either the stellarvue.com website or the SV Yahoo Group site), it does not appear that any SV scopes that are currently being produced are using lenses that are attributed to either LZOS or LOMO as sources. However, LZOS and LOMO lenses have been used at various times in the past.

#23 Eddgie

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Posted 17 February 2013 - 06:26 PM

I am an aperture red neck. 115mm over a 101mm.

I have to agree with Jon though.

It seems to me that you may be under the impression that a big aperture is of little use under suburban skies.

This simply is not the case.

I can see far more in my 14" scope than in my 8" scope, more in my 8" scope than in my 6" scope, and more in my 6" scope than my 5" scope when observing from my central Austin Tx back yard.

In fact, I have owned a half dozen 4" scopes and if anything I found them far less satisfying to use under typical light polluted skies.

The sky will wash out if you use too low a power (to big an exit pupil) in a small scope.

I would recommend that you do some research on the topic. What you will find is that you can often see more from a suburb using a big telescope than you can see in dark skies using a small telescope.

And when you do take a big scope to dark skies, you get a super-wow out of it.

But if you must have a refractor, get as big a refractor as you can afford, manage, and mount.

After owing maybe 15 refractors, the only one that interests me even slightly is my 6" APO. Nothing smaller has given me any real observing pleasure in my own sky conditions.

But my 14 gets used about 20 times as much from my back yard.

So I agree with Jon first, and the 120ED recommendation second. The more aperture, the better, especially if you are under typical light pollution. The more aperture you throw at most deep sky even under light polluted skies, the more you see.

M13 is barely a glow from my back yard in a 4" scope. In 6", it is only barely granular.

At 8", it starts to show some stars.

At 10", it becomes quite resolved.

At 14", it is fantastic.

Trust me, aperture is not wasted under typical suburban sky conditions.

#24 Eddgie

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Posted 17 February 2013 - 06:53 PM

Also, this...

About 6 years or so, there was the "Great 4" Refractor Shootout" posted in this very forum.

Several dedicated observers lined up a half dozen 4" telescopes and spent a great deal of time trying to decide on which scope was the "Winner." They did a huge amount of comparisons.

And guess which 4" telescope won? It was the one that seemed to show the sharpest, brightest image by most of the testers on most of the targets.

And the winner was???? The biggest 4" telescope.. :roflmao:

See, as it turns out, one of the telescopes in the review was a 110mm telescope. While I protested vigorously about the outcome, the testers did not buy in to the fact that a 110mm telecepe would have a distinct advantage due to it's better resolution, better contrast, and better light gathering. And yet the biggest of the 4 telescopes was judged by almost all of the reviewers to have delivered the best views.

So, my advice to anyone wanting a good 4" scope is to get the biggest 4" scope they can find. A 120mm one would make a really fine 4" telescope.

So, at least as 4" scopes go, aperture is everything, because when compared to all of the other 4" telescopes the biggest 4" scope was judged to provide the best views...

Funny, eh? I love this story.

Try to find the review. Oh, I mean the review was totally excellent and a wonderful job. It was a superb article. I was just not at all surprised that the biggest scope won. I thought it was totally unfair to have a telescope with 10% more aperture in the mix because well, it had to me a complete advantage simply because it was bigger.

Think about that when you make your decision. 120mm to me should make a pretty fantastic 4" scope.

#25 Bill Barlow

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Posted 17 February 2013 - 07:50 PM

Stan,

What objects show color? Are you using higher magnifications when the false color shows up? I am strongly considering this scope, but you are the first person who has said they see false color in the SV115T. I think that SV praises this lens design as being totally color free. Thanks..

Bill






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