iStar Optical

More than a Telescope Manufacturer

iStar Optical is known for the design and manufacturing of quality telescopes and lenses for individuals and the astronomy industry. No less than a half dozen professional telescope builders and manufacturers in Europe and the US now implement our lenses in their telescopes. We have produced a number of objective lenses for Universities and observatories around the world including Mount Stromlo observatory   in   Canberra   Australia,  INAF-Osservatorio

Astronomico di Brera in Italy, Swarthmore College in the USA, Hohenkarpfen Observatory in Germany, Pic du Midi  observatory in France and Université Libre de Bruxelles in Belgium.

What you may not know is iStar Optical also designs and produces lenses for “Opto Mechanical” and “Opto Electronics” applications. Lenses and optical assemblies were recently produced for the physics departments of MIT

in Massachusetts USA and Caltech in Pasadena California USA. Specially designed lenses for Holographic applications were delivered to L-3 Communications EOTech in Ann Harbor Michigan USA. Recently iStar Optical became a registered supplier of optics for the prestigious STAR Labs of Lockheed Martin Aerospace and Defense Company.

Call or email today to find out how iStar Optical and their staff of engineers and opticians can provide solutions to your optical needs.

The iStar 204/1200 – Second Generation 2014

(from John Croker, Australia)

I’ve always had a liking for refractors. My first serious instrument was a Vixen 102 ED SS, a beautiful 660 mm focal length lightweight refractor, easily supported on the Vixen GP mount. Almost made for each other. Since 2001 its been the best portable telescope I’ve used. In subsequent years I have acquired a Vixen NA 120S (a Petzval designed 120 mm / 800 mm FL), and a WO 66 triplet which is a great travel scope. I had always wanted a bit more aperture yet liked short tubes for maneuverability  so when I saw a 6” Antares in 2006 I went ahead and bought it. I’ve had a few good years of observing with this scope, mainly from my house in the northern suburbs of Sydney, with its attendant light pollution. I decided I wanted a bit more but I could never quite bring myself to order anything I felt justified in spending upon until I noticed the Istar range. A little research and I was hooked. In Feb 2014 I placed my order and sent over three and a half thousand USD to Mike at Istar and settled back to wait. I also sold my Antares – I had to make room.

Nearly 11 months later the Istar finally arrived. I had picked the f/6 “Comet Hunter” model. Part of the delay was in remaking the tubes, as Istar had found the original assembly just too heavy. I have to say I appreciated this as the new scope was 16 kg (35 lbs) down from 20 kg (44lbs). 9 lbs is a lot extra when you are trying to get it onto a high dovetail on a G 11 or similar mount! The scope was well packed in a thick cardboard carton with the scope itself

surrounded by aerated foam blocks. Istar is clever in their packing and had placed the 3.5” WO focuser, in its own padded box, between the lens end of the scope and the box, making extra protection for the lens. The focuser was fitted with William’s new Rotolock eyepiece / diagonal lock system which is a self centering double opposed taper. I have to say this in its present form is one of the best eyepiece locking systems I have used.

This second generation Istar comes with an extendable dew cap, some 400mm long offering excellent dew shielding. A flat lens cap snaps in place with embedded magnets holding it to the outer ring of the dew cap. The white tube (I asked Mike for white because you can see it better in the dark) is held in 2 lined quick release tube rings, with several M6 tapped holes. I ended up drilling some extra holes in my Losmandy plate to accommodate the 60 mm spacing of the M6 holes (the Losmandy plate comes with predrilled holes 40 mm apart). I also mounted a 15x40 mm Al bar along the top of the rings to act as a handle and guide or camera mounting bar.

First light was in Sydney, with street lights and all. Seeing to mag 3.5 (E Crucis) I looked at Omega Centauri, Jupiter and M42. I was using a WO dielectric diagonal and switching between a TV Pan 35 and a 17mm Nagler IV – the latter quite the best eyepiece I’ve ever owned. I have to say it was the best view of each of these objects I have had in any telescope in Sydney. I quite forgot how many stars there

were in the trapezium. A few nights on I looked at “cluster row” - the Jewel Box (NGC 4755) along through Carina (NGC 3532, 3199, 2867)– some magnificent clusters with a hint of nebulosity. The Jewel Box really jumped out at me – crisp, well coloured stars just like a box of bright jewels. As James Edwards suggested  in his review of the gen one “beast” this scope scoffs at street lights. I spoke to Ales at Istar about how good the seeing is. Ales is the Istar designer and  technical expert and very willing with his advice. The performance of this telescope is a combination of aperture, of course, the high quality glass Ales has been able to source (I would say it’s ED but Ales says no, he can’t call it that) and the exceptional workmanship of the lens makers.

A week or so later, I took the scope to its long term home, my holiday house n the Blue Mountains west of Sydney. The altitude of 1140m and having a mountain range separating the view from the lights of 5 million people makes for clear dark skied – when it’s not cloudy or drizzly. After a few ‘bum steers’ I got a clear night, wheeled out the scope on the G11 and looked at the same little collection as before.







more >

Moonraker Nebula Class 4-inch f/12 refractor featuring iStar 100 F/12 Achromatic Doublet

Phoenix WXT 204-6 LT

This telescope is a great performer in its class, and is a joy to use! It is awesome for observing deep-sky and fantastic for the Moon! CA? Yes, the CA is undeniably present on bright objects, but I think it is up to a person how much it is tolerated or not? For example, I could not take off my eyes off the Moon for an hour or so, even when CA was present, because I was immersed so much in observing the craters and other fine surface details! Is this telescope good? Yes, darn good :-) Actually, this refractor may be the perfect outreach kind of scope!

I am very happy with it!


The focuser is an AP 2.7" with greased rack and   pinion  and  I  added  an  AP  extension

between the focuser and the tube so that it can be exchanged later on for a 4" AP focuser if needed. The length of the system is exactly as planned. I have 7" from the end of focuser to the focal point and it comes into focus with a diagonal even for me who wears strong glasses. The 7" back focus also makes the telescope bino friendly, however, this will need to be verified. The tube mounting is a 15" AP ribbed plate with Parallax rings. The tube is not heavy considering its size. My AP 900 is good enough to hold the refractor, but I have to balance it carefully.



Whitehorse Canada


Viktor Zsohar Proudly Presents the iStar 228mm F/7.7 ATM Build

Strongly Reduced Chromatic Aberration doublet  with a near SEMI APO performance.

Ares WFX 150-5 R50 SLIM

iStar is proud to introduce an all new, second generation Ares WFX 150mm F5

with exciting features our customers were asking for.


  The Heart of this wide field Comet Hunter is a recently designed 154mm F5 R50-Slim improved Achromatic doublet.

This new lens is substantially lighter and Chromatic aberration is reduced to near Semi APO levels with unmatched

resolution. New white tubes with all inner parts completely re-designed for reduced weight. Split construction counter cell

with fully retractable dew shield, bayonet style locking mechanism and slim lens cap held by neodymium magnets. Each OTA is

shipped with 360° fully rotatable dual speed 2.0” WO Rack and Pinion focuser in white finish and a set of 160mm “Fast Lock” Mounting

Rings. All scope parts are precision CNC machined in the European Union out of aircraft grade alloys and powder coated. All this for only $2085.



  Watch for the release of our next generation line of super lightweight 8" Refractors the Phoenix WXT 204mm F6, Perseus AXT 204mm F9 and Asteria AXT 204mm F8 R45-S.

Stay tuned!

Over the last several years, iStar Optical has established itself as a market leader in providing high quality achromatic and semi- apochromatic refractors at fair prices. Over this length of time, I have watched the company grow and innovate in new and exciting ways, providing customers with objectives for ATM builds or complete telescopes in traditional or truss tube formats. Recently, the company has been introducing exotic glass types into their designs, thus providing large aperture with improved colour correction to sate a growing demand from the amateur community.


Having fully test driven several iStar refractors, I eventually settled on acquiring one of my own; a beautiful 127mm f/12 R30 Asteria (aka ‘Tiberius’) which has given me immense pleasure in the pursuit of my hobby. Earlier this year, iStar owner, Ales Krivanek, contacted me inquiring about whether I would be interested in test driving yet another product from their first generation stock; a 6 inch (150mm) f/8 achromat. Naturally, I obliged and the following is a summary of how I got on with it.


Fit ‘n’ Finish

The optical tube assembly arrived in perfect condition having travelled across Europe to Scotland from its source in the Czech Republic. The instrument – a first generation iStar model – was very carefully packed and a quick examination of it confirmed that all was well. Just a few moments of casual inspection of the telescope will convince you that the workmanship that went into fashioning the tube assembly is light years ahead of the more ubiquitous Synta designed CR6.


While many have complained that the original, first-generation iStar tubes were over-built and too heavy, I have come to like them an awful lot. For me, they are reassuringly sturdy and reminiscent of the days when quality achromatic refractors were being built by the world’s famous optical houses. They feel old fashioned and look old fashioned.


Like all iStar objectives I’ve had the pleasure of using, the one that accompanied this tube was perfectly assembled within its high quality, adjustable aluminium cell. The crown and flint components are properly spaced, fully-multicoated and are surrounded by a massive dew shield that protects the lens and all but guarantees hours of hassle free observing without the need for a dew band.


J.P. Brahic - French amateur astronomer

achieving professional quality images using his iStar 228 F/9 H-Alpha Optimized Doublet

Phoenix WFT 204-6 FIRST LIGHT REPORT by Ralph Aquirre, California, USA (August 2014)

Last night I had an opportunity to take my first peek at my friend James new iStar Phoenix 204 F/6. Here in Sacramento, some of the weather forecasts were showing a chance of rain but our best source was saying no rain till the following afternoon. Because of this, we decided it would be smart to just set up on his driveway, just in case the weather turned south on us. When I went to his place, his scope was already set up.

He was on his driveway with 3 streetlights all in sight, and a near full moon just rising. We didn't care, we are passionate astronomers and having an opportunity to just set up and look at this beast on his G11 would have been good enough even if it remained cloudy.

Fortunately, the skies cleared up and the clouds had moved away. Despite our horrible lighting conditions, we were ready to have a first light at this beautiful masterpiece.

First off, I'd like to say the 204/F6 was a perfect marriage for the G11 with an optional one foot extension pier installed. For the first time ever, the big mount looked completely matched with a big refractor mounted on it. When  I  got  there,  the  scope  was  not  balanced  on the mount properly. I removed  one of  the counterweights and ended up with two 21 pound counter weights on the G11.

I slid the scope back in its massive stock tube rings because

because it seemed somewhat front heavy, even with a 2" diagonal and a 41 Panoptic installed. So 41 pounds of counterweights on the G11 was the perfect weight for the big optical tube.

I noticed the Moonlight focuser was adjusted a little too light for his two inch eyepieces, so using an allen wrench, I tightened both screws under the focuser which stiffened up the focuser slightly, and the focuser then felt excellent. When the scope was pointing straight up, the big Panoptic moved like glass in and out of the draw tube. The rotating focuser was extremely fluid, very smooth and precise, exactly what you would have wanted.

With the 12" Losmandy Extension Pier on the mount, the mount was at a perfect height with the tripod legs full extended. Even when pointing straight up, it was at a perfect height for sitting for observing or just leaning forward, and when observing above the roof lines, we were able to stand comfortably. Had we been in open flat horizons, we may have needed one small step on a two step ladder I always take with me. Overall, this scope was matched perfectly to the G11.

With our mediocre skies, I was able to see Cassiopeia and moved the scope over to the double cluster in Perseus.

Even  with  the  near  full moon about 30 degrees from our

target, the big red giants in the double cluster were very prominent and the entire star field was picture perfect pin points. With a big smile, I told my friend Jim that the optics on this scope was excellent. Every star with the widest eyepiece possible was absolutely a perfect pinpoint. It couldn't have been a better image. I panned around and found the ET Cluster, NGC 457. Even with the wide field 41 Pan, the large red and blue star forming the eyes of the ET cluster focuses perfectly. I put in a 14mm ES 100deg eyepiece (85x) and the cluster just jumped into view. Again, perfect pin point stars across the entire field of view, just absolutely perfect optics. This scope had been up for maybe 45 minutes before I started using it, so even in that short amount of cool downt time, there were no issues of waiting for the glass to equalize or settle down. The outside temperature was about 55 degrees and despite the clouds just clearing away maybe 2 hrs earlier, there were no signs of puffy stars.







ATM Build by Jack, September 2014

It’s been obvious for several years that my TV85 and cheap 6 inch Dob in our Florida home consistently outperform (on the usual lineup of urban targets) my TV102 and 10 inch Dob - Newt with a premium mirror in our upstate NY home. Atmospheric and local seeing is very good most winter nights on the east central coast of FL, and poor (on those few nights when stars are visible) in NY. So I transported...


"The universe is full of magical things

patiently waiting for our wits to grow sharper."

iStar Optical

Eden Phillpotts