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Post by Ales - iStar Optical on Jul 5, 2015 14:06:19 GMT -5
Hello everyone, recently we designed several new Semi APO and APO doublets. First model going to production is 160 F8 Semi APO. Lens in cell will be offered in about 5-6 months, OTAs about 2-3 months later. Check out more currently available details on our website here: istar-optical.com/objective-lenses-iv.html The 180mm F9 lens in cell will become available by end of this year or beginning of 2016, production of this model depends on performance and success of the 160mm Semi APO. We are also considering 204 F10 Semi APO, 180 F11 APO and 160 F11 APO. All these has already been designed but only some will be submitted into production, based on actual interest from you guys. See attached spot diagram of 160 F8. Beautiful flat field with good color correction. There will be halo around bright objects, but nothing compared to standard achromat or even R35 anastigmat. Anyone interested, contact me at: ales@istar-optical.com
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Post by Viktor Z. on Jul 9, 2015 17:01:29 GMT -5
Hi Ales,
I LOVE the idea of large semi-apo and apo lens with long focal length! Especially the 204 f10 and 160 f11 caught my interest!
Viktor
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Post by boomboom on Jul 9, 2015 21:47:41 GMT -5
Hi Ales,
A 204 f10 grabbed my interest too.
I'll be ready in about three years :-(
First I'm building a 2" shaft Pillow Block Mount :-)
Matt
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Post by cherubino on Jul 14, 2015 8:51:26 GMT -5
ohh… a 204 F10 could be really nice… I wait news about it..
Paolo
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jaymocha
Full Member
Bought me the Asteria 204-8 R35...
Posts: 46
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Post by jaymocha on Nov 17, 2015 6:45:21 GMT -5
Greetings Ales;
I am wondering how the production of your Semi APO lenses are coming? I am VERY interested in the 204 F10 Semi APO. I think I could be ready to purchase either the lens cell or a full OTA as soon as they come out or very nearly. Please let us know what a good time frame might be to expect these on your website.
Jason
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Post by cherubino on Sept 16, 2016 8:12:37 GMT -5
Hello Ales,
I'm interested in purchase a 160 F8 ED or 180 F9 Have you any news about it?
Thanks!
Paolo
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Post by Ales - iStar Optical on Sept 17, 2016 7:58:21 GMT -5
Hello Paolo, so far I have only 2 or 3 people interested in such instrument. I will seriously consider 160 F9, 160 F11 or 180 F11. This would be a doublet with ED special flint element. This scope would most likely perform at around R60, approaching good semi APO with nice tight spot and most likely only single color halo around bright objects (not this very colorful halo seen in most achromats at F12 and below). I do believe that I mentioned projected prices in some of my previous posts. You guys give me some feedback about which one of these 3 models would you like to see being produced and I will do my best to take care of this after my surgery and after I get better. Most likely by end of this year or beginning of next year.
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Post by cherubino on Sept 17, 2016 14:49:20 GMT -5
Ciao, Ales.
I give you my personal opinion. A 160 F11 with a very good control of CA surely could be a definitive planetary and doble stars telescope. We can only remember the superb Takahashi FC 150 (f11,3 doublet version) I'm sure the 160 F9 could be really close to a f11 version with the plus of a more gestible dimension and weight. We know that long focus large refractors are really little usable and the marked don't give them large production numbers (important consideration when you have do to business!) Probably a 160 F9 version is more easy to manage and, why not, it could be a market winner (no one make a such interesting instrument!) So.. if you realize a 160 F9 with not only a good CA control but, more important, no problems of spherical aberration, I will be the first to get one. Keep this in mind. For me a 180 F11 is too big and requires a very strong mount (surely with a playload of 50/60 kg or more to be stable and to minimize effects of wind and vibrations). Is not logic to have a large refractor (the difference from a 160 to a 180 mm. in high visual resolution are really suitable) on a standard mount.. A CEM 60 or a EQ8 (entry level price in the range 30-40 kg) are not strong enough to carry a 180 f11 and probably they reach theirs limit with a 160 f11.. I have just sold my Takahashi FCT-150 (OTA of 22 kg...I'm sure you know the scope..) cause it is too heavy and my CEM-60 on a giant fixed column could not provide a very stable support for it. Realize a good 160 F9 with a final weight of 14/16 kg and you can sell a good numbers of it. The quality of images must be of course really good in terms of geometrical aberrations. With a good project you can minimize the effect of CA (Sidgwick rapport of 1.5 is really negative using a normal fraunhofer scheme) and create a stunning achromatic refractor for visual observations. Remember that in visual planetary applications is more important the correction of the red part of spectrum despite the blue part but I'm sure you know this better than me.
Paolo
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Post by cherubino on Sept 17, 2016 15:00:22 GMT -5
Another consideration:
the market offers top level APO in the range of 16 cm. of clear aperture.. TEC 160 FL, AP 160, CFF 160, Stellarvue 160 (ex) and now other 150 made in China triplet. Their price is really hight (with no logical reasons) speaking of AP 160 and TEC 160 FL but very competitive in the case of Synta Triplet. I had occasion to use a SW 150 and in visual applications it is really close to the TOA 150 (that costs 2 or 3 time more). So... there is no space for a 160 top level optics. Keeping in mind your enterprise vocation your project have chance to be a market winner if it propose a third way to the stars. Forget a perfect apochromatic result... this is important only in deep sky imaging. Try to offer a competitive telescope for visual observers. A 160 "semi apo" lens in cel could not cost more of 1.500 USD and a complete scope doesn't go over 3K USD. If this is not obtained You will have no chance to make a good business cause people surely prefer a APM/LUNT 152/1200. I love ISTAR "mission" and hope to have one day the chance to get one of your scopes.
Paolo
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Post by cherubino on Sept 17, 2016 15:04:51 GMT -5
And ALES... most important thing... my best wishes for a speedy recovery!! health first and foremost!!
Paolo
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Post by Ales - iStar Optical on Sept 18, 2016 7:15:38 GMT -5
Paolo, very unfortunately, it is not possible to produce a good 160mm semi APO doublet in acceptable quality for 1500 dollars. Our actual cost of manufacturing is substantially higher than that. It is true that the market in 150mm aperture class is well covered but I think I will develop one of these 160 F9 doublets and see how they perform. I agree that these instruments do need good quality mount but with this new technology of manufacturing, assembly and choice of special thin alloy tubing I will be able to help weight of such OTA down to some 10 kilos excluding focuser and rings. These scopes will not be overly "nose heavy" too. Well give me some time to get well after my surgery and I will look into this again. Thanks to others for participating in this discussion. This is my last post before surgery (some 18 hours ahead). I will get back with you guys after I get well. Thank you for your patience and understanding, cheers Ales
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dan
Junior Member
Posts: 25
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Post by dan on Sept 21, 2016 0:00:29 GMT -5
Ciao, Ales. I give you my personal opinion. A 160 F11 with a very good control of CA surely could be a definitive planetary and doble stars telescope. We can only remember the superb Takahashi FC 150 (f11,3 doublet version) I'm sure the 160 F9 could be really close to a f11 version with the plus of a more gestible dimension and weight. We know that long focus large refractors are really little usable and the marked don't give them large production numbers (important consideration when you have do to business!) Probably a 160 F9 version is more easy to manage and, why not, it could be a market winner (no one make a such interesting instrument!) So.. if you realize a 160 F9 with not only a good CA control but, more important, no problems of spherical aberration, I will be the first to get one. Keep this in mind. For me a 180 F11 is too big and requires a very strong mount (surely with a playload of 50/60 kg or more to be stable and to minimize effects of wind and vibrations). Is not logic to have a large refractor (the difference from a 160 to a 180 mm. in high visual resolution are really suitable) on a standard mount.. A CEM 60 or a EQ8 (entry level price in the range 30-40 kg) are not strong enough to carry a 180 f11 and probably they reach theirs limit with a 160 f11.. I have just sold my Takahashi FCT-150 (OTA of 22 kg...I'm sure you know the scope..) cause it is too heavy and my CEM-60 on a giant fixed column could not provide a very stable support for it. Realize a good 160 F9 with a final weight of 14/16 kg and you can sell a good numbers of it. The quality of images must be of course really good in terms of geometrical aberrations. With a good project you can minimize the effect of CA (Sidgwick rapport of 1.5 is really negative using a normal fraunhofer scheme) and create a stunning achromatic refractor for visual observations. Remember that in visual planetary applications is more important the correction of the red part of spectrum despite the blue part but I'm sure you know this better than me. Paolo I would agree with this for the most part. I favor the F-11 over the F-9 because of the physical FL for easy eyepiece power on planets and moon plus it should have better CA. The F-9 would probably appeal to a larger number of buyers just because it is physically shorter. The CGEM-DX would max out at about an 1800 mm FL such as a 150mm F -12. It's the length of the tube more than the weight that is the limit (more wind torque), the difference in weight between 1440mm and 1760mm would be only one pound in a 7 inch carbon tube. The best of both worlds would be an F-10 at 1600mm. (Remember Goldilocks and the 3 bears) though a F-10 was not mentioned as an option, maybe this design would be a possibility. Some considerations in the design parameters here should be the final determining factor. Some of these fancier doublets have a rather steep curve on surfaces 2 and 3 which are very sensitive to lens spacing and especially centering. I would think a more forgiving curve here would make for a better scope. - Dan -
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Post by antoine on Nov 18, 2016 5:46:39 GMT -5
Hello Alex
My name is Antoine and I live in Paris, France
I hope you're recovered from your health problems
I'm interested in the glasses you assembled
I plan to acquire a Istar in 2017 I hope and I have several questions for you because I hesitate between two models
Can you assemble a complete refractor ED Semi-Apo 180 mn F11 with ( OTA with microfuser, finder, rings and dovetail ) ?
Can you assemble a complete refractor ED Semi-Apo 204 mn F10 with ( OTA with microfuser, finder, rings and dovetail ) ?
I need to know :
the price, weight, availability
Is a Skywatcher EQ8 or Losmandy Titan mount OK for the 180 mn and the 204 mn ?
Thank you in advance for your replies
Cordially
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Post by Ales - iStar Optical on Jan 13, 2017 14:33:22 GMT -5
Antoine, I replied in detail via email. Stay in touch! Ales
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