iStar 127 mm (5”) R30 F/12 Doublet Refractor
My first telescope was a refractor. As a star struck 8-year-old it represented the ideal image of how a telescope should look. It was a model 9TE-5 Tasco 60 mm (2.4-inch) f/11.7 700 mm focal length alt-az telescope sold by Sears, Roebuck and Company. It was advertised disproportionally as a 234X telescope. With a refractor you could aim directly at the stars. In a Newtonian you look indirectly at the stars sideways. How a reflecting telescope works just didn’t make sense to my young mind. I have had several reflector telescopes over the last 60 years, but I always gravitate back to refractors.
I have always been a visual observer. The nights when the eye was the best detector for viewing critical details on lunar, solar, and planetary bodies changed in the mid-1990s ending a tradition of visual observing for scientific purposes that began 400 years ago. The advent of solid-state detector technology (e.g. CCD and CMOS) coupled with computer processing made it possible to exceed the amount of detail the eye could detect through “lucky imaging.” This new technology was quickly adopted by the amateur astronomer community.
Review of iStar Optical PHOENIX 204-6 Achromatic Refractor
From James S. McEvoy
iStar PHOENIX 204-6 Achromatic Refractor
I have been an amateur astronomer since 2002 and have owned just about every type of telescope commercially available. These include 8, 11, and 14-inch SCTs, 4” ED apochromatic refractor, and 15” Dobsonian. Life happens and circumstances change. We ended up in rural northwestern Wyoming about 2 miles outside of a small town. It is reasonably dark at my home but not pitch black due to scattered bright lights on adjacent properties as well as sky glow to the west from the town. How to observe?
I am strictly a visual astronomer and enjoy the moon, planets, double stars, and selected deep sky objects. As I’ve gotten older, I’ve noticed that I’m less comfortable standing while observing for very long. I prefer to be seated. Hence, a large Dobsonian reflector, while tempting, was not ideal. The mount that I use has a weight limit of about 60 pounds. While that is robust, an 11 or 12” SCT would be about the limit. I especially enjoy the views through refractors and decided that the best option for more photons was a large aperture achromat.
Review of iStar Optical 150mm (6”) F/15 Objective Lens
From Russ Leonard, Litchfield Hills Amateur Astronomy Club, Connecticut
Ever since I got my first telescope over 50 years ago, I have wanted a big refractor. It probably started when I was looking through the old Sears and Edmund Scientific catalogs in the mid 1960’s. I was happy with my 90mm F/10 Newtonian back then but looked forward to the day when I would have a “real” telescope.
Forty plus years go by and I have 8” and 11” SCT’s and a couple of small APO’S. My interest in astronomy continues to grow and I retire in 2014 and have plenty of time to fully enjoy my hobby. Last fall I decide to build the big refractor that I always wanted and I contacted Ales at Istar.
The F/15 lens was shipped promptly and arrived several days later. I had been worried about damage during shipping but that was totally unwarranted. It was packed so well it could have been drooped from an airplane and still survived intact. Upon initial inspection it was flawless and perfectly free of any dust or contaminants.
Four months later my beast of a scope is finished with the exception of some cosmetic finishing touches. It resides on a homebuilt Alt-AZ mount with a friction clutch design. It moves freely with finger touch control very similar to a large dob. The entire unit is 500 lbs of rolling telescope, mount, oak pedestal and counterweights. It may look bulky but it is very easy to move around and use. I would never try to convince anyone that it is practical but it sure is fun.
I have recently compared its performance to my other scopes. Does it have some false color? Yes, but it is very minimal as you would expect from an F/15. The contrast and clarity of the images is amazing. When observing the moon, you feel as if you are on an Apollo mission looking out the window. Jupiter was stunning the other morning as I watched the shadow of Ganymede traverse the surface of Jupiter. The very thin crescent Venus has looked very impressive as it approaches inferior conjunction. Open star clusters and double stars are perfect targets for this scope. For light gathering it is similar to my C8. For a sharp image, clarity and contrast it easily surpasses both my C8 and C11. The C11 is obviously better for faint fuzzy deep space targets. It certainly is not a grab and go scope but it is everything that I have ever wanted and more. Dealing with Ales was a pleasure and the product has lived up to my expectations which were very high.
Russ Leonard, Litchfield Hills Amateur Astronomy Club, Connecticut
159 mm F/15 iStar achromatic doublet mounted in folded style refractor designed and made by Takashi Tsumura from Japan.
Few words about the scope and mount written by Mr. Tsumura:
My telescope is a 15cm F15 achromatic refractor. The structure is a folded type, and the material of tube and parts is GFRP. Therefore, this is short (1200mm) and light (11kg without finder and sub scope). I'm using it with iEQ45Pro AZ mode, and the focuser height is equal to DEC axis. I can observe by easy posture. I have 32cm reflector, but, in a city, sky is bright (can see only 3 magnitude stars) and seeing is bad in Japan. So, I'm mainly using this 15cm to observe double stars, open clusters, planets and moon. This lens easily resolve Antares, E and F in Trapezium, etc. I compared with 120mm Apo. (TAKAHASHI) side by side. My telescope was winner. (But, I have no experience with 150mm Apo.) When used Anodizing Screen, resolve more easily. Even if use a cheap eyepiece, it shows pinpoint star image at view circumference. So, open clusters are very beautiful. At moon, blue harrow reduces the contrast slightly, but a Semi Apo Filter improve the contrast. For a conclusion, this is the most useful telescope for me.
GFRP Parts made by Takahashi Tsumura
iStar 150mm F/5 R50 Semi APO Doublet Mounted in Custom Made OTA by Skylight Telescopes of London
I have had a liking for low power wide field telescopic views as long as I can remember. I was looking for a telescope to supplement my Istar 200/1200 WFT that would be portable enough to easily transport in a compact car and utilize a 3" format 30mm 100° field eyepiece. The Istar 150/750 semi-apo lens was perfect as it would give me 25x and a huge 4° true field of view. I had Skylight Telescopes of London, England design and build the telescope around the Istar lens and a 3.5" Feathertouch focuser.
Lens 127mm F/8 achromatic doublet
Frank Sady, Australia
I recently purchased a used Istar 127mm f.8 lens in cell, the Perseus model. I have since built a telescope around it and used it for the first time last night. My friend and I both own several scopes including Takahashi models. My friend has the 130mm Tak toa model, but was so impressed with the views with my iStar that he hasn't been able to stop talking about it.
He considers, as do I, that there is little if any appreciable difference in image quality, they are both wonderful telescopes.
Where the Tak 130 TOA has the edge is that it is totally C.A free. Naturally I was expecting some of the usual Achromat C.A that normally comes with achro's of that size and focal length, I already own a 150 f.6.
What really surprised both of us was how little ca it showed, it is barely there. The thing we found most astounding was that when looking at the moon, there appeared to be no increase in the barely noticeable ca on the limb as we increased the power of the eyepieces incrementally from 30mm to 5mm. What a wonderful objective. I am delighted with this telescope and very proud to own it, I can't wait to show it off at my astronomy club.
You and your company are producing a wonderful product, thank you.
Frank Sady, AUSTRALIA
The iStar 204/1200 – Second Generation 2014
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.
Moonraker Nebula Class 4-inch f/12 refractor featuring iStar 100 F/12 Achromatic Doublet
Moonraker, not the best known, but known by the best... We take great pride in creating each and every telescope and we all know that the the engine driving the OTA is the objective. In this regard we use classic optics both old and new and Istar create stunning classical doublet objectives with a modern twist at a great price that deliver stunning well corrected vistas... Period!
"Moonraker are proud to use iStar optics in many of our telescope builds."
Viktor Zsohar Proudly Presents the iStar 228mm F/7.7 ATM Build
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 APextension 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.
2015 Solar observers meeting in France Featuring iStar 204 F8 TCR Refractor
We had great success with the 204mm F8 TCR at the R.O.S. meeting! People were amazed with the open design, the good looks and care taken in producing it. Many people observed the Sun through it.
One guy had a personal made refractor with a 150mm Istar lens…of course now he has a mind to buy a 204-8. We had intermittent weather some clouds, but no rain.
This year there were 120 participating amateurs surpassing the 60 attending last year. This attendance did not include the who also enjoyed viewing the Sun through our instruments. This event is increasing in notoriety every year with also very interesting lectures. Here are 3 photos. Stay tuned!
Bernard Durand, FRANCE
iStar WXT 204-6LT refractor review
“My God! It’s full of stars!” proclaimed David Bowman, as he approached the monolith in the classic science fiction movie 2001: A Space Odyssey. That’s the feeling I had whilst experiencing the new iStar WXT 204-6LT rich-field refractor under a dark, country sky. Before I elaborate on this, it is important to define what ‘rich-field observing’ is all about.
Small-aperture telescopes with short focal lengths are excellent for low-power, ultra-wide-field observing. In contrast, large aperture, long focal length telescopes are the instruments of choice in the pursuit of high resolution targets such as the Moon, planets and double stars. Rich field occupies the niche in between the two. The ideal rich-field telescope will have a decent aperture and present moderately large fields of view in order to probe the depths of the deep sky at intermediate image scales.
Arguably the ideal rich-field telescope will present unobstructed images over a field of view of approximately two degrees. While a fast (f/5 or faster) Newtonian of 200mm (eight-inch) aperture or more is a good rich-field telescope, an achromatic refractor of similar specifications can do considerably better, owing to its lack of a central obstruction and maintenance, as well as its provision of a wider true field. Enter the iStar WXT 204-6LT.
WHAT CAN ONE EXPECT FROM AN iSTAR 150 F/15 STANDARD ACHROMATIC DOUBLET?
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...
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