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Post by Ales - iStar Optical on Dec 30, 2012 9:20:37 GMT -5
Dear friends, Just today I ran across several new links on CN, AM and elsewhere, posted by Istar competitors and/or people who cannot handle Istar’s success in lens and telescope design. To my total “surprise” I found out that our R30 and R35 anastigmatic doublets are nothing but a MARKETING HYPE and manipulation with poor customers mind. Our competitor is trying to tell others that a simple, cheapest achromatic doublet will actually perform substantially better than any R30 doublet! Not only is this a total nonsense, but statements like this show a great amount of disrespect to any fellow amateur astronomer. Most of us do think and do use our own brains, regardless of what we hear or read. I don’t believe that you or anyone else will base their opinion on substandard “study results” performed by a direct competitor who has no direct experience with our product to begin with They also suggest that R30 doublet is a simple, classic Achromats with only the red part of spectrum “hanging out” so the resulting CA halo is predominately reddish-pink instead of purple-blue. Nothing could be further from the truth! All R30 doublets are made with short flints and special, more expensive crowns than any classic Achromat. This is how we achieve all this “magic”. The design color-shift is only a bonus to all the good stuff. You never hear a bad word about completion from Istar. I simply wonder why our competition is spending their time, money and other valuable resources to throw dirt on Istar and its products. We stand behind our products and if we say that R30 or R35 anastigmatic doublets offer a substantially smaller spot size, greatly improved resolution and amount of chromatic aberration comparable to a classic system of 1,35x longer focal length, than these are all true facts and you can easily confirm all this under stars. I am not going to get involved in a never-ending battle with any competitor. I rather let market to prove them dead wrong over time. I just ask you not to abandon a great product without giving it a fair trial.
I will do one thing sometimes during early 2013. Together with our master optician we will put together an in-depth description of how our R30 doublet works and what can be expected in terms of visual and even photo performance. We are all extremely busy, time is very scarce but since the competition would not simply be quite I will present you all with the complete picture. In the mean time, to buy a R30 or R35 doublet is a very wise thing to do, especially now, when the Raycorr correctors are finally in sight. Prices of ED doublets and triplets are out of reach for most of us. As you may know, R30 lenses and Raycorrs are optimized for each other. See spot diagrams on Istar Scope Club for more detailed info.
We designed and sold many dozens of R30 and R35 doublets from 127mm F12 to 250mm F11. We received ONLY a very positive feedbacks from all of our customers and none of these lenses ever came back to us. I believe that this is what really matters.. and so should you
Best regards,
Ales Patrick Krivanek ISTAR Optical, owner
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Post by Watcher3 on Dec 30, 2012 12:14:10 GMT -5
Looks like you set the record straight in the CN thread, Ales. Just very curious how Gord could have missed the mark. It's like he only paid attention to little snippets of info available here. While I don't think he has anything to gain, it certainly doesn't make ISTAR look very good to point out one little aspect of their lenses. To ignore the fact that spot size and other aspects of your designs would contribute to the amount of detail to be had is just speculation at it's worst, even if he's only talking about Jupiter and Mars.
Due to health, job, and family tribulations, I haven't had the opportunity to properly first light my scope yet, but I did have a couple of rushed minutes with it. It's plain to see, even at F/5, that these lenses are something VERY special!
I wouldn't worry too much about that CN thread. reality trumps speculation, and the word is getting out. ISTAR is the only place to go for quality, affordable, big refractors!
Joe
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gord
Full Member
Posts: 82
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Post by gord on Dec 30, 2012 19:51:22 GMT -5
Hey All,
Joe, I don't think I've missed the mark on this. Remember this is a very specific test we are talking about.
I've spent some time looking at the spot plots on here for the 6" F8's, and to me the R30 does not look better than the achro, just different. I made a comment about this in the CN thread. Other than the purple halo in the achro, the blue hangs out and the other colors are very well focused. In the R30, both blue, and especially red hang way out. In fact they hang out more than the purple does in the achro.
However, the longitudinal graphs are not shown, so we can't say how things look as the blue is shifted tighter. But it looks to me that this is not the optimal design for planets where there is a red component.
But as I mentioned in the thread, the apparent lower intensity of the blur in the R30 would seem to me to be a bonus in the case of double star splitting. I know Mike C. has commented on this being a use case where he has been very impressed, and looking at the spot plot I could see how that could be the case.
And it is correct, I don't have anything to gain, but do think it's important to see more knowledge shared as well as the good (AND BAD!) aspects of products. There's nothing worse than the disappointment of something not performing as expected.
Clear skies, -Gord
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Post by Watcher3 on Dec 31, 2012 1:59:45 GMT -5
I understand Gord. I want to see the good and bad of ISTAR as well. The only thing I take issue with, in your CN thread, is the "theoretical ranking" for the specific use. You know as well as anyone, that something like that, written by a respected CNer, such as yourself, can leave a negative impression on a lot of readers, even if later proven wrong in a real world head to head comparison.
I just think that in the search for truth, one should not start with an assumption. I think, once you do that, you tend to look for anything that supports your position. It's one thing to ask if people have done a head to head with any of the lens types mentioned, it's quite another to give an opinion without those comparisons.
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gord
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Posts: 82
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Post by gord on Dec 31, 2012 11:57:36 GMT -5
I understand Gord. I want to see the good and bad of ISTAR as well. The only thing I take issue with, in your CN thread, is the "theoretical ranking" for the specific use. You know as well as anyone, that something like that, written by a respected CNer, such as yourself, can leave a negative impression on a lot of readers, even if later proven wrong in a real world head to head comparison. I just think that in the search for truth, one should not start with an assumption. I think, once you do that, you tend to look for anything that supports your position. It's one thing to ask if people have done a head to head with any of the lens types mentioned, it's quite another to give an opinion without those comparisons. Hi Joe, I understand what you are saying, it's important that we are clear about what is being said. Remember, this is a specific test case of two planetary targets where the red component is very important. These are important targets for a lot of people (me included) and to learn that design choices can have a negative impact on that is a very "oh no!" kind of moment! I was really seriously considering one of the APM Chinese ED's, but the revelation that it may not be the best for Jupiter really caught my attention. I would be really unhappy if I had got one and then found this to be the case. My understanding (previously) was very simplistic in terms of what is "better". If someone has an ED offering, or an enhanced design, it must be better (always) than a simple achro, right? And one ED is the same as the next, right? It was that simplistic of thinking. Reality though, is different and obviously things are not that simple. And what it takes is someone with the real knowledge of this to explain it. I've seen these effects from an observational perspective, for example the violet halo around an bright object in an achro, and how things improve in a design where things are properly focused. Where I didn't understand really, was how that translated back to what we see in the design graphs and plots. Now that is becoming more clear. And from that you can start to make predictions as to what should be the result. In terms of the list I mentioned, as I have stated a couple of times now, this is a straw-man, a hypothesis based on the theory put forward. We're trying to apply some of the scientific method here. We need to refine it based on input, and then put it to the test to either prove or disprove it. What we really need to see with the R-series is the longitudinal color graphs to see how things look as the focus is changed. The spot plots only show the best focus in green right now. And Matt, no, I haven't had a chance to see one in person yet. From the thread on CN, it appears there is a member here in Ontario that has one. Maybe we can get a side-by-side test with them. I know the performance of the 6" F10 is pretty good, even with the false color. It's been a very interesting discussion and I know I've learned a lot about the technical details behind all of this, and the really important aspect to it that there can be real effects in real world use. Clear skies, -Gord
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Post by Mike on Dec 31, 2012 14:51:17 GMT -5
Hello Guys, I have been holding off on this discussion both here and on CN. It took me a long time to learn to brush off the "expert" opinions over on CN. Instead of these guys out enjoying their equipment they're too busy behind their computers over analyzing every aspect of a telescope. I've also found that any new product or technology other than what has already been done simply cannot work. Little people like Ales Krivanek and his optician cannot possibly make something a little better. Take all your graphs and charts and throw them in drawer. I have had several "shoot outs" between Classic designs and R30s. The R30s do what they were designed to do. That is: When actually looking through the scopes show less CA than their equal F ratio cousins the Classic Achromatic. I know how to evaluate the performance of a telescope. I have been doing it professionally for many years. You would think that people would be happy that a company like Istar is producing quality refractors. People need to wake up and smell the roses. The smell of death is coming from several manufacturers when it comes to quality refractors. Why not embrace and support those who are producing what you love. I have found that if you kick at every little barking dog all you will get is a sore leg. Ignore it and it will probably go away.
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Post by Mike on Dec 31, 2012 14:58:33 GMT -5
One of the geniuses who claimed 9 months or more ago he had a refractor design that was going to change the world has yet to produce a single working model. This individual is the first to take apart anything anyone else thought of that he didn't. Istar IS producing innovative working designs that are in the hands of the public. Jealousy is such an ugly emotion.
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gord
Full Member
Posts: 82
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Post by gord on Dec 31, 2012 16:41:12 GMT -5
I have had several "shoot outs" between Classic designs and R30s. The R30s do what they were designed to do. That is: When actually looking through the scopes show less CA than their equal F ratio cousins the Classic Achromatic. Mike, I don't think anyone has been questioning the amount of CA present. The question is, do they perform as well in terms of showing the actual detail on a target with a lot of red information such as Jupiter/Mars? And is it rendered the same way, is it sharper, is it softer, is focus more difficult? The general consensus seems to be that the red component is the more important to planetary detail on these two targets than is the blue. And this is obvious if you look at the color of the main details on these two targets. It really comes down to horses for courses. Not every design is ideal for everything, and there's nothing wrong with that. Clear skies, -Gord
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Post by Mike on Dec 31, 2012 23:16:34 GMT -5
Gord, I have spent a great deal of time observing through R30 telescopes. How much time do you have? I and "many" other seasoned observers used an Asteria 127-12 R30 and a Phantom 152-8 Fluorite for several days during last years Winter Star Party in the Florida Keys. We experience conditions that most of the Continental US never experience, extremely good seeing. Very stable air that makes it difficult to see scintillation at all. Jupiter was well placed in the sky. I assure you the Asteria was able to not only be brought to a "sharp" focus but show great detail of the planet. There were two highly respected Belgium men who had there choice of any number of scopes but chose to observe with me three nights in a row. Their keen and experienced eyes had nothing but the highest praise for that R30 example. Yes, the fluorite APO triplet out performed the 127-12. At $6000 more I would hope it would. But most observers were simple blown away at the performance of a 5 inch telescope at that price. In fact, the scope performed so well it resulted in the sale of two scopes and a dealership. Paper work is fine for geeks... but I say nothing beats real world experience. I briefly look at the paper work, then I get out under the stars where it counts. My eyes tell me how well a scope performs. If you choose to sit on the couch and critique designs, more power to you. You are entitled to your opinion and I respect your right. I don't respect anyone who has no time behind the eyepiece of a particular scope and then points out it's short comings. This is simply unjustified and bad for business. Your "red" flag, no pun intended, causes potential customers to second guess Istars integrity. Your post has turned into an Istar bashing on CN whether you intended it to or not. Justify all the reasons you want. Bottom line is... it is not good for Istar. But you may feel good about warning off any body that might get duped into buying our misrepresented product.
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Post by Ales - iStar Optical on Jan 1, 2013 4:42:38 GMT -5
Hello my amateur astronomer friends, This discussion has reached the point where all parties should take a deep breath, think hard, get back to basics and sort our differences over a scope party and glass of wine. I value everyone’s opinion but sometimes it is needed to take two steps back and observe the situation in a greater picture. After all, what comes out of the eyepiece is what counts. So now, (for a second time) I am more eager than ever to compare Jupiter image with Classic Achromat and R30 doublet side by side. We have done this in the past with three similar scopes and none of the professionals doing the comparison test noticed any softness in image or lack of detail when observing with R30 scope. Actually quite the oposite. A greater, enhanced and crispier detail were reported both on the moon and Jupiter during this long test. We tested R30 against similar achromat (Istar) and two 140mm ED APO Triplets, both made by a very respected companies and both costing nearly 4x the price of Asteria R30. We used same eyepiece set (Pentax), same diagonal and all test were performed on same night after two hour initial lens cooling time. In any case, if this loss of detail is true to any measurable extend, we are immediately going to design and produce F12 R30 scope fine tuned for Planetary use only. So even the most demanding observer will be completely satisfied with their choice of an Istar lens or Istar OTA. And I’m dead serious about this offer. We can have such scope on the market in 3 months after we find out that there is a real place for such instrument on this market. I wish you all great day, respectfully, Ales Patrick Krivanek
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gord
Full Member
Posts: 82
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Post by gord on Jan 1, 2013 9:47:55 GMT -5
Happy New Year all!
Ales, Mike, you are right, we have been discussing the theoretical merits based on optical theory, the next step is to put them to the test. Here is a suggestion:
Approach Jeff to see if he would be willing to test your R30's.
Jeff is extremely knowledgable in both the theory and observation. He is also very respected and is one of the earliest IStar customers, and has experience with extensive testing of many telescopes of all different kinds. He has one of the 6" F10 Steinheil achromat's like mine and that many others have, and has a positive opinion of it as I do mine.
Send him a 6" F8 R30 since this would be an equivalent match based on the 30% improvement. In fact it would be a slight advantage to the R30, but there has to be some flexibility with what's available of course. I think he also has a (or some) regular 6" F8 achromats so that could be compared as well.
Anyway, just a suggestion. At this point, I believe I am no longer in a position to offer my own experiences as input as if I report anything other than positive results, my claims will be viewed as being biased with a pre-conceived conclusion. I have to defer to others to report their findings.
Clear skies, -Gord
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Post by Mike on Jan 2, 2013 12:55:08 GMT -5
Gord, One last question before I heed Ales suggestion to drop it is this... Why do the posters over on CN keep saying they are looking forward to your report on the R30 when you do not own one.
"My claims will be viewed as being biased with a pre-conceived conclusion."
The above statement is true because you have zero time behind this scope, right?
I respectfully ask you to do two things: Stop rating the R30 with no eyepiece time under your belt and let the posters on CN that you do not own an R30 and are theefore not in a position to rate one.
Mike
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gord
Full Member
Posts: 82
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Post by gord on Jan 2, 2013 21:49:22 GMT -5
Mike,
I have already stated this in both this thread and the one on CN. You seem to be asking that people not discuss or critique the design. Why?
What we have been doing is analyzing the design and others based on the information available and making a prediction. Valery has shared his experience based on deep observational and optical design & manufacturing skills, that which far exceeds either you or I. Based on the design information, predictions can be made. Then tested with observation.
The design of the APM doublet showed it would not show traditional violet false color and would show some red halo. It should also show reduced sharpness due to this red de-focus. It has been tested twice now and the above predictions match what was reported.
Speaking of the R30 design, you have not shown some information that is helpful for describing the performance characteristics of a refractor optical system, namely the longitudinal aberration graphs the same as what APM publishes. These show very clearly how a lens will perform. Have you shown this information? Your spot diagrams seem to show the above described characteristics, however there are some parts of the diagrams that seem unclear. For example:
-How do you calculate the 30% reduction in CA value? Is it the size of the color blur of the area where the red & blue overlap? Is this the total size of the blur? Is it a measurement of de-focus between green/red or green/blue? You have stated characteristic of the design, but I haven't analyzed it closely until now and am not understanding how you come to this value based on the plots you have shown. -Why is the airy disk size different between the two 6" F8's? Is it just the scale of the diagram (although both show the same scale label)? If they are the same size (which it should be), why is the blur so much larger on the R30?
Again, the most descriptive way is to compare by LA graph where the exact amount of de-focus across the FeC lines can be seen.
Thank you, -Gord
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Post by bn1777 on Jan 3, 2013 20:51:26 GMT -5
Good bit of to and fro here guys , All the tech talk is as Matt says is mostly above my head but I have owned a North Group 127mm f7.5 triplet up until mid 2012 and now have an Istar 127mm doublet f8 . I think I have now used the Istar ( 2 months almost now , on every clear night ) to make a quick comparisim between the NG triplet and Istar doublet . Ok the NG definatly has better controlled CA , thats to be expected ( over $2k , compared to $630 total cost of build ) so is the triplet 3.5 times better , not on your life it was very good but not 3.5 times better , more like 1/2 x better .
The moon , the Istar shows a faint colour fringe , the NG none , but the views are identical apart from that .
Jupiter . same as the moon , but I feel the Istar shows more intricate detail in the bands and GRS .And the CA dissapares for me very quickly once I start observing the planet .
Saturn , nothing between them up to 250x when the NG pullls away slightly .Both max out at about 340x .
M42 , Identical in every way .
Deep sky , Double stars , As above .
No , I am more than happy with my 127mm Istar Doublet and dont miss the NG triplet at all , and I had the pleasure of building my scope my self, total satisfaction . Thanks Ales and Mike for a world class product . I will do an in depth review with photos soon . You cant compare oranges with apples without trying both first . Brian.
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Post by bn1777 on Jan 3, 2013 21:00:27 GMT -5
Oh yea , I use TelVue Radians 3mm -12mm and Naglers 13mm -20mm and Panoptics 19-24mm so all I see is a product of the scopes , not the eyepieces . Brian.
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