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Istar refractors Pros and Cons?

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#1 Dakota1

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Posted 02 April 2013 - 10:10 PM

Are these refractors worth the money they cost and is the build quality there? They seem to have a good selection of different scopes. From what I can find they are made overseas in Europe if I am correct. Are they a new company or have they been around in Europe long? I wonder if they have a warranty service here in the USA? I see OPT has them for sale. Availability on some of them you have to call them for that information its not online by phone only. I am going to get a refractor this fall be interesting to see if they are worth there cost and if they become popular on this side of the pond. Thanks
 

#2 jrbarnett

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Posted 02 April 2013 - 10:29 PM

The optics are made in China. The tubes? Dunno. Europe, maybe. Or the US. Their HQ is in Page, AZ, USA, these days. They haven't been in business all that long. They do have an interesting selection. I'd love to see some independent interferometer reports for their larger optics done with meaningful parameters. If the optical quality is there, then they are a good value. If not, then I'd say there's not as much to be excited about.

Regards,

Jim
 

#3 mikey cee

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Posted 03 April 2013 - 12:15 AM

Well I for one am an extremely satisfied customer. After a year's plus usage I find this lens is truely top notch. I can honestly say I can see no room for improvement. Double stars of .5 arc seconds are easily split and Mars and Jupiter are phenominal to say the least. Seeing conditions obviously need to be cooperative and those times are far and few between but this lens still amazes. Ales K. Istar's owner is a straight shooter and will personally see to it that you will become a satisfied customer. I exchanged approximately two dozen e-mails with him. Go ahead take the leap. ;) Mike

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#4 RGM

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Posted 03 April 2013 - 05:29 AM

I am also a happy owner. I believe they have a 5 year warranty period. I needed some work done on my focuser recently. Instead of repairing my existing focuser, they exchanged mine with a new/latest model focuser. Scope is built like a tank, and therefore heavier than other scopes. I rate it as high quality. They do have options to reduce weight on their website.
 

#5 Jim Curry

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Posted 03 April 2013 - 06:07 AM

Mr. Cook:

I purchased both the 4" & 6" f/12 regular achro lenses and built OTA's. The 4" star tests perfectly at 200x, the 6" perfect @ 300x.
 

#6 Darren Drake

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Posted 03 April 2013 - 07:42 AM

Double stars of .05 arc seconds are easily split and Mars and Jupiter are phenominal to say the least.


Wow that's some really good glass there lol.
 

#7 CounterWeight

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Posted 03 April 2013 - 07:57 AM

Folks that own them seem happy, at least those in the Istar user group and here - but I think in the end 'value' and etc are a personal call. I think you need to be aware of mount requirements if you goi with one of the long focal length and larger apeture.
 

#8 mikey cee

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Posted 03 April 2013 - 10:24 AM

Double stars of .05 arc seconds are easily split and Mars and Jupiter are phenominal to say the least.


Wow that's some really good glass there lol.

Ah c'mon man lay off me. I meant to put down .5 arc seconds! :foreheadslap: Mike :roflmao:
 

#9 jrbarnett

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Posted 03 April 2013 - 10:57 AM

Also, there are lots of "happy users" in users groups for every brand of scope. Heck, there are even Meade fans if you can believe it. :grin: The cold harsh light of some objective interferometric test data using methods and metrics identical to those used to test other optics would go a very long way to establishing or undermining the value proposition represented by Istar optics. Large optics are hard to fabricate well no matter where in the world you figure them.

It would be great if Rohr on astro-foren were to test a handful of non-cherry-picked Istar lenses. For me, that would establish quickly whether the goodwill is earned or just derived from "clubiness" that follows every brand, good or bad. It would also give an idea how these lenses stack up to other brands whose lenses have already been tested.

The large (6" and larger) Chinese achormatic optics tested thus far on astro-foren haven't been very good. This is why I think the absence of similarly derived data for these optics gives reason to pause. It would be a huge "win" for Istar if scopes already in users hands (not hand picked examples) were tested in that neutral context and shown to be exceptionally high in figure quality. Conversely, if the test results looked a lot like the other big Chinese achromats tested on the site, it could be problematic for the business. I'll put it another way: if there were one or two actual-customer-owned Istar scopes tested on astro-foren and they were shown to be in the neighborhood of 1/6 wave or better, I would buy an Istar tomorrow. If instead they look more like the DKD and other large China acromatic optics tested on the site (a little over 1/3 wave) I'd have zero interest in owning one at any price.

"Do you/we feel lucky?" :grin:

Regards,

Jim
 

#10 jhfenimore

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Posted 03 April 2013 - 11:24 AM

I purchased an Istar 6" F15 achro lens a few weeks ago to use in a folded refractor on a dob mount I plan to build this spring and summer. Chose the Istar based on availability (at age 72, you don't want to be on a multi-year wait list), and to a lesser extent, on price. Have only built Newtonian dobs, so this will be an interesting experiment. When I am able to test it on the night sky, I'll be happy to pass along the results, if anyone is interested.

Jack
 

#11 telescopemullet

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Posted 03 April 2013 - 11:52 AM

You can add me to those who can attest to the great quality of the optics and OTAs of these scopes. I owned a D&G scope and the ISTAR was of better build quality and had optics that were just as good.
 

#12 Sean Cunneen

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Posted 03 April 2013 - 12:25 PM

I purchased and built a scope around an Istar 6" f15 objective. Over a couple of years maybe a hundred people looked through it and I received lots of compliments. I sold it when I came across my current Jaeger's lens which I find to be sharper but dimmer(the Jaegers is uncoated). My reports are that I had a large objective with no major errors (astigmatism, SA). The lens was not perfect, but I thought the performance outstanding for the value and there were few times my scope did not have the best planetary images around. I have not dealt with Istar complete scopes, though I did check one out at a star party. I felt the tube was very heavy and I did not like where the scope balanced aesthetically. Istar builds their OTAs in a premium way, with machined baffles and a thick tube. I felt you'd have to add perhaps 15# on the focuser end to make the OTA sit properly on a mount. That additional weight would make an already heavy tube just about at the limit for one person to move around. You will need a very robust (HUGE!) mount as well.

Pay no attention to where this or that is made, we live in a world of stuff being made everywhere. Istar has their own factory making their own stuff. Istar service and communication is first rate, except when they post anything :poke: :tonofbricks:
 

#13 cliffy54

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Posted 03 April 2013 - 12:41 PM

Moderators should not get involved. Look at the title of the post. Pros and Cons. Mr Barnett is stating his opinon of Cons.

I to would like to see some testing numbers also. :)
 

#14 telescopemullet

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Posted 03 April 2013 - 12:48 PM

Moderators should not get involved. Look at the title of the post. Pros and Cons. Mr Barnett is stating his opinon of Cons.

I to would like to see some testing numbers also. :)


They are not his opinions as he has never used one. He is using conjecture to cast doubt upon a fine product, big difference.
 

#15 jrbarnett

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Posted 03 April 2013 - 01:12 PM

It is not an opinion that there are no published, neutral, interferometric test reports for Istar optics. I suggest that astro-foren is the best we have since we have test reports constructed using identical methodologies and criteria for many, many lenses from many, many sources. That is FACT.

It is not opinion that the large Chinese-made achromatic lenses tested on astro-foren using these standardized methods have been relatively poor in quality; below that which I would accept as a good quality optic. That, too, is FACT.

Here is the menu of astro-foren.de test reports:

http://www.astro-for...ischer-Berichte

Here are examples of poor quality large Chinese achromatic optics:

http://www.astro-for...romat-154-22...

http://www.astro-for...hbarer-Achro...

http://www.astro-for...romat-154-22...

Here is the DKD website:

http://dkdoptics.com/

Here is Istar's webpage for optical groups:

http://www.istar-opt...m/istar_031.htm

Here's a DKD lens with the accompanying "test report" (scroll down):

http://dkdoptics.com...ctus.asp?id=108

Here is an Istar "test report":

http://www.istar-opt...m/istar_083.htm

It is not opinion that they look to be quite similar in parameters and presentation. That is a FACT, too.

Now every DKD optic that shipped with telescopes tested on astro-foren.de was accompanied by a similar test report, yet the actual figure quality of the optic when tested more rigorously wasn't consistent with that comforting report.

Therefore because we have no non-anecdotal evidence of high quality large Chinese achromatic optics, and do have some neutral, non-anecdotal evidence of large Chinese achromatic optics (shipped with glowing "test reports" no less) with poor optics, it is reasonable to proceed with caution and not be too hasty to accept anecdotal opinions from those who have drunk the kool-aid...er...I mean offered only pride of ownership endorsements rather than real data. :grin:

But hey, it's your money. I do have a question for the Istar owners. That ring on the front of the objective on which the focal length, aperture and company name are painted - can that be threaded off the front of the cell or is it glued on? I'd like to see the cell with the nameplate removed. Thanks!

Lastly, Istar hasn't helped itself among more skeptical and careful potential customers. It was Istar's principal to played "hide the banana" with the FACT of Chinese origin for Istar's lenses very early in the game. You see, I just want the FACTS, not the fanboism. A couple of 1/6 wave Istar objectives on good 'ol astro-foren, and I'd not only lose my skepticism but also become a customer. But as thing stand, a bunch of club members pumping glass they already bought, who display a severe case of "need to believe" doesn't cut it in my book.

What's the harm in wanting some FACTS? Heck, I'll pay to have telescopemullet's objective shipped to Rohr for testing and then back to him.

:winky:

- Jim
 

#16 Gord

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Posted 03 April 2013 - 01:41 PM

Moderators should not get involved. Look at the title of the post. Pros and Cons. Mr Barnett is stating his opinon of Cons.

I to would like to see some testing numbers also. :)


They are not his opinions as he has never used one. He is using conjecture to cast doubt upon a fine product, big difference.


You know, this is one comment/attitude that I have seen presented here quite a few times (and not just related to a single vendor/thing...) that I just can't agree with; the whole "this person doesn't own/hasn't used so is in no position to say anything". *Everyone* is in a position to share things here, be it personal experience first hand, or observations from afar.

Of course, I *AM* an IStar owner and so by your own position on this, you shouldn't have any problems with me sharing my experience! :grin:

I'll start with saying that Jim has hit on a lot of it already (and has things pretty clearly laid out). I'll add my own experiences and other information separately.

Clear skies,
 

#17 Gord

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Posted 03 April 2013 - 01:52 PM

But hey, it's your money. I do have a question for the Istar owners. That ring on the front of the objective on which the focal length, aperture and company name are painted - can that be threaded off the front of the cell or is it glued on? I'd like to see the cell with the nameplate removed. Thanks!


Jim, I'm pretty sure it threads on, although I've never completely removed it. I'll have a look the next time I get a chance.

Clear skies,
 

#18 jrbarnett

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Posted 03 April 2013 - 01:56 PM

CNer Sasa also had an Istar - briefly. I'd love to hear him share his own "hands on" experiences with the instrument. :grin:

- Jim
 

#19 stanislas-jean

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Posted 03 April 2013 - 03:07 PM

When buying an Istar 150F10 doublet I was pretty sure that this was a chineese one.
China is a strange company of several sources.
When visiting some I was surprised to see the catalog of OTA in a room and some special orders at the corner, 8, 9, 10" and more.
You know that this is mass production and into the lots there are good ones.
Having got a problem with the 1st 150 showing spikes at high power the second one was without spikes and a little better in acuracy.
The bulletin is what it is, it is always possible to perfom a roddier on by yourself in order to be confortable. I did.
This is not the initial bulletin but the acuracy remains above the minimum required.
A L/4 PTV for the refractor equals a L/8 reflector on glass surface. The strehl given on the website is what can be expected and there is it seems at the receipt a polarimetric light test to see internal stressing of the glasses.
This is not may be a DGO but this works. The 150mm tool gave me images of Mars and Venus that didn't get mostly.
Jim reported the importance of the optic elevation to keep less seeing locally from ground. Absolutly right.
With the one way light into tube there is a gain with internal air currents.
Products are not the more exceptionnal optics to find but this works more than honestly. Better than the synta line.
Doublets are engraved on the front, not a stick glued on the front.
I dismounted the doublet from the cell to see how it is installed/ very well, not pinched, well spaced, diametrally spaced, all surfaces FMC. Easy to maintain and to collimate.
I improved the assembly with the installation of 6 screw helping to collimate the lenses together for avoiding any shift.
People using these doublets on the sun found them very correct in Halpha, me on Mars and Venus.
Stanislas-Jean
 

#20 careysub

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Posted 03 April 2013 - 03:21 PM

What we need is a Consumer's Union for telescope owners.

It would be a membership organization in which, upon joining, members submit a list of their optics that they own and information about acquisition for compilation into a confidential database.

The organization would then select and contact members to provide free testing of their optics so as to get a random or representative sample of vendors without having to front the money for purchases.

Members would have log-ins for access to the complete test database.

Additionally the organization could purchase optics anonymously for testing and then offer them for auction to members after testing to recoup the purchase money.

A suitable incentive structure to get members to pay sufficient membership fees to support this would be necessary.

Sort of a pipe dream, I know. But such a thing might be workable.
 

#21 De Lorme

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Posted 03 April 2013 - 03:45 PM

That is a great idea! This way the manufactorers know that
if they don't produce quality telescopes we won't buy.
Anybody can say it's great but now we would know it's great.Who do you know that would have the skills and time to
do the test on so many scopes? De Lorme
 

#22 Rutilus

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Posted 03 April 2013 - 04:01 PM

The nameplate is just threaded on. This is my 150mm f/15 lens with it removed.
Not had much time to do much testing with mine, but what I did see, Jupiter and a few double stars
including Sirius B looked very nice.

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#23 jrbarnett

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Posted 03 April 2013 - 04:04 PM

Thanks Rutilus. That's exactly what I was looking for.

Regards,

Jim
 

#24 Dakota1

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Posted 03 April 2013 - 06:35 PM

Well like I said in the beginning I intend on buying a good quality refractor around Xmas. I have not seen an Istar scope around this area as of this time and no one in our club has either. I could consider one once more is known about the optics. Looking at there forum its hard to judge those who have them and there findings. Like Jim said it would be nice if one of the companys that can do a quality test on there glass and give an unbiased report in laymens language would be helpful to future buyers of Istar scopes.
If I want to invest 2 to3k on a scope I sure want to know ahead of time that I am buying a good quality product regardless of who made it.
Its a shame someone had to get up on the wrong side of the bed and jump on another CN member. Totally uncalled for especially when he does not even know what another person has knowledge of. Just my opinion Thank you
 

#25 mdowns

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Posted 03 April 2013 - 06:47 PM

Count me in as a charter member for the consumer union of telescope owners.Killer good idea and not near so far fetched if we keep it within the confines of cnights,were we can regularly share and post info. The vast,diverse background here is a goldmine of all things telescope!
 






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