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Equipment Discussions >> Refractors

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De Lorme
professor emeritus
*****

Reged: 12/30/08

Re: Istar refractors Pros and Cons? new [Re: careysub]
      #5775964 - 04/03/13 04:45 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


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Rutilus
Carpal Tunnel


Reged: 12/17/10

Re: Istar refractors Pros and Cons? [Re: careysub]
      #5775990 - 04/03/13 05:01 PM Attachment (94 downloads)

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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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Istar refractors Pros and Cons? [Re: Rutilus]
      #5775995 - 04/03/13 05:04 PM

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

Regards,

Jim


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B. Cook
professor emeritus
*****

Reged: 10/18/10

Loc: No. California
Re: Istar refractors Pros and Cons? [Re: jrbarnett]
      #5776272 - 04/03/13 07:35 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


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mdowns
Pooh-Bah
*****

Reged: 06/12/10

Loc: Englewood,FL
Re: Istar refractors Pros and Cons? [Re: careysub]
      #5776298 - 04/03/13 07:47 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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Roy McCoy
Pooh-Bah
*****

Reged: 10/13/05

Loc: Glendale, AZ
Re: Istar refractors Pros and Cons? [Re: De Lorme]
      #5776350 - 04/03/13 08:20 PM

Quote:

Who do you know that would have the skills and time to
do the test on so many scopes?





Rohr

(see Jim's links above)

We could collectively/periodically send a box of scopes to Astro-Foren.
He clearly knows what he is doing and already has a large list of evaluated scopes so we would only need to supply models he hasnít done.


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dan_h
Carpal Tunnel


Reged: 12/10/07

Re: Istar refractors Pros and Cons? [Re: De Lorme]
      #5776352 - 04/03/13 08:21 PM

Quote:

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




Who do you know who would be willing to take the heat from the membership when a product doesn't live up to the standards that the testing indicated it should? You don't have enough money to pay any reputable testor to take that kind of risk.

dan


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LAF
member
*****

Reged: 11/30/04

Re: Istar refractors Pros and Cons? [Re: telescopemullet]
      #5776499 - 04/03/13 09:12 PM

Totally agree

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tomharri
sage
*****

Reged: 09/19/08

Loc: USA
Re: Istar refractors Pros and Cons? [Re: LAF]
      #5776567 - 04/03/13 09:46 PM

Huuummm.....Jupiter last night with Istar 5" f/8 R30, homebuilt, $1000 in it, 5mm Kiyohara ortho(?). 200x, very little purple haze, great defined detail equal to good 8" reflector. Two moons going behind planet, Europa going in front of Jupiter, could see moon for 20 minutes along edge but then lost it. What's not to like?

Meade 127mm ED/APO f/9, $1700+new ota way back then. Around $1000 used today. No purple haze, defined details about same as good 8" reflector. Good deal if you can find one.

Factor in inflation/worth of money, you get a little less scope new today for about same price that you got yesterday.

Why all the hate? Sounds like a deal to me.


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Gord
Carpal Tunnel
*****

Reged: 01/06/04

Loc: Toronto, ON, Canada
Re: Istar refractors Pros and Cons? [Re: B. Cook]
      #5776598 - 04/03/13 10:04 PM

So on the topic of IStar pro's and con's, I'll share my experience and observations.

Jim has given a lot of information here already and I'd say he's covered it will, including probably the biggest point, the unknown. Who they are, where they get stuff, it's pretty well known although I don't think I've ever seen it admitted anywhere that DKD is the source.

On my own experience, I've got the 6" F10 classic achro, and have tested another model that isn't offered any longer. My 6" is one of the early offerings, perhaps even from the very first batch offered when they first started back around 2009/2010. I believe Stanislas' sample is from the same time.

From my experience with it, it's a good achro, was great value at the time (and a little less so as the prices have crept up). Quality is good, I'd say above the previous offerings from Synta and the like. They were supposed to be around 1/5th wave, and mine is likely in that range.

After doing more extensive testing, I don't think it's as good as I initially felt in terms of absolute numbers and the very highest power tests (500x) are not as nice as I had hoped. Mine is not showing clear low order SA, but rather what appears to be balanced high-order SA. But I need to do further testing with some better filters to really understand it. It does though put up a nice image to 300x for sure, and at low powers it is very nice!

One thing that Jim has highlighted is the real unknown about *how* good they actually are since most tests from people are not very detailed and nothing really measurable like we see from Mr. Rohr. The interferometer report that Jim mentioned is a good example. This was presented around the time of when I got mine, but there seem to be a limited number of them all kind of looking similar and around that 1/5 wave error range. Seems unlikely that all could have such similar looking reports and the very same looking ones have been tested on astro-foren and came up quite different. I'm thinking it could just be a sample report and there would be whatever variability you would normally get between samples. Most also seem to be for around the 6" size.

I do think mine is a touch above the older Synta's (from 10 years ago), but I'm not so sure about more recently. My experience with some newer Synta's (and what I see on astro-foren) is that they have improved as well. Reports also seemed to suggest they were not far off of D&G either, but after seeing some of the D&G results, that may not mean they are particularly good since there are apparently some real stinkers out there even from them!

Still, I think the classic acrhos are good value. But I wouldn't say that applies to everything they offer. They have been very focused on the "R-series" lately and that's an even bigger unknown. Other than Mikey Cee here, there are few reports. There are a few that have got them, raved briefly about how amazing they were (with no details), and then the scopes were up for sale.

There was some good info posted about what is likely going on with these and how it comes with some big drawbacks (in real performance) and when combined with the large increase in price, they don't seem like a good value. Again, no real tests done to say for sure, but the reports don't seem to match up with the comments about superior performance, but what they do seem to suggest is just what had been suggested (trade-off performance, an alternately tuned achromat). Here's a good example of that by some questions/observations that Mike has noticed:

Larger lens cool-down time thread on IStar forum

The reports of difficult focusing on Jupiter are spot on with what had been suggested by those that are far more experts than I.

On other designs, they have too not done so well. The triplet LaF lenses for example. They weren't able to make those work and the only one in the wild (a 140) never stayed very long with the original owner. I'm not sure there was ever any others. The 160 version never even got that far (and I can speak from experience on that one...).

It seemingly is to do with the complexity of things. If they are more complex, their (IStar's) track record is worse. The Raycorr corrector is another example. They have been talking about this for years now (since 2010 at least) and it has never materialized. Not surprising either since in researching what it's all about, it turns out it's REALLY HARD TO DO! Many have tried and many have failed. But it's always "just about ready".

On service and support, they generally do well on this in trying to make it right. They also offer something that few others do, and that is a "custom" source for a specialized optic, yet very affordable compared to others.

If there is anything where they don't do well related to this, it's on communication of expectations, over-selling, over-marketing and then not being able to deliver. That and since they don't do things (the optical side...) in-house, they don't have the control to handle things not being perfect from the sub-contractor. What they get is what they get.

On the structural side, they do control things more (as I understand it) and the OTA's are extremely well built. If anything, they are over-built and they suffer then from weight. Have never seen one in person yet, but they sure look well built.

So, my summary:

PROs:
-Good (to even great) value for classic achro's
-Ability to do custom stuff
-Have had good response in trying to make things right and please customer
-Very well built OTA's

CONs:
-No real concrete reports on how things really are (especially on the R-series)
-Poor track record on the more complex offerings
-Too much marketing, not enough substance
-Heavy OTA's

Clear skies,


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Istar refractors Pros and Cons? [Re: dan_h]
      #5776640 - 04/03/13 10:22 PM

Rohr. He's already doing it. He's outed plenty of bad glass and identified much good glass. No issues with threats from the hawkers of junk optics so outed. Why? Because truth is a defense to *any* claim such a purveyor could concoct. The last thing junk-mongers want is the attention a failed effort to suppress truth brings.

He also already has a large and growing database of test reports. That's a great start. Best of all it costs not a penny to view his reports. It's all very transparent. That's great for consumers who want facts. Not so great, potentially, for the "true believers" though.

Regards,

Jim


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timps
sage


Reged: 02/24/13

Re: Istar refractors Pros and Cons? [Re: jrbarnett]
      #5776849 - 04/04/13 12:18 AM

. Heck, there are even Meade fans if you can believe it.

Does that mean I'm making a wrong decision in looking to
buy a 14" Meade SCT?


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Istar refractors Pros and Cons? [Re: timps]
      #5776860 - 04/04/13 12:33 AM

T'was a joke. But why not head over to astro-foren.de and see if there are any Meade SCT test reports? You can get apples-and-apples, non-anecdotal, measurable test data for both Meade and Celestron SCTs, as well as other kinds of scopes.

Regards,

Jim

Edited by jrbarnett (04/04/13 12:37 AM)


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herrointment
Carpal Tunnel
*****

Reged: 03/12/11

Loc: North of Hwy. 64
Re: Istar refractors Pros and Cons? [Re: timps]
      #5776861 - 04/04/13 12:33 AM

Heck, I once bought a Rambler!

You'll be fine.


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timps
sage


Reged: 02/24/13

Re: Istar refractors Pros and Cons? [Re: jrbarnett]
      #5776866 - 04/04/13 12:39 AM

My German is not good enough to navigate their website.

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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Istar refractors Pros and Cons? [Re: timps]
      #5776873 - 04/04/13 12:42 AM

Use google translate. It's free and not too bad.

Regards,

Jim


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cliffy54
professor emeritus
*****

Reged: 03/14/10

Loc: ma
Re: Istar refractors Pros and Cons? [Re: herrointment]
      #5777063 - 04/04/13 06:51 AM

A Rambler.

Edited by cliffy54 (04/04/13 06:53 AM)


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Istar refractors Pros and Cons? [Re: cliffy54]
      #5777077 - 04/04/13 07:05 AM Attachment (43 downloads)

There is nothing wrong with my 127mm f8 Istar achromat , it performs very well .
I too was out last night looking at jupiter and at 250x the image was still sharp with great detail seen on the planet .
I dont know where they get their lenses from but mine is good one .
Total cost of my build $650 aud .
Istar lense in its beautiful cell was only $450aud of this delivered to me here in Australia , great value and after sales service .
You wont do better for an Achro for this price .
Brian.


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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Istar refractors Pros and Cons? [Re: beanerds]
      #5777092 - 04/04/13 07:12 AM Attachment (72 downloads)

Here is the moon taken using a HTC One phone held up to my 8mm TV Radian about 140x .
Note the little bit of CA on the luna limb , but its very well suppressed for a 127mm at f8 and the image is super sharp apart from that .
CA does not bother me at all , some people hate it . Every ones different .
Brian.


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Mark Costello
Carpal Tunnel
*****

Reged: 03/08/05

Loc: Matthews, NC, USA
Re: Istar refractors Pros and Cons? [Re: herrointment]
      #5777194 - 04/04/13 09:02 AM

Quote:

Heck, I once bought a Rambler!

You'll be fine.





IMO the best car my parents had was a '61 Rambler station wagon.


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