Istar Refractor Gallery

[John]

I've posted a few general photos of my Istar 150mm F/12 achromat refractor a while back but while I was giving the scope a gentle clean (not the optics !) I thought I'd take some pics of some of the details of it's construction for anyone who might be interested in this sort of instrument.

It's a very well engineered scope to my eyes, in a completely different league to my Skywatcher ED120 and Orion Optics 12" dobsonian. It's manufacturered partly in the Czech Republic, Austria and the USA with the objective lens being made in Asia but assembled, tested and installed in the scope in the USA.

The focuser is a 2-speed USA made unit manufacturered by Crawmach but with some custom Istar engraving. It's not as butter smooth as the Moonlite on my ED120 but it's pretty decent to use. It has a 2.5" drawtube. The visual back and adapter is made in the Czech Republic by Istar:

The dielectric diagonal is made for Istar to their specifications and they put their own backplate on it engraved with the Istar logo:

The main tube is some sort of magnesium alloy with 3mm thick walls. It is manufactured by Istar in Austria and has 4 custom designed knife edged CNC machined baffles bolted into it with flush hex screws. The interior has a textured matt black finish and it really is dark in there !. Each baffle has a rubber ring around the outer edge, where it meets the inner tube wall. This ensures that no light comes through between the tube wall and the baffle edge. The first photo is from the focuser end (focuser / visual back removed) and the second is from the objective end with the objective and cell removed:

The next photo shows the objective in it's cell and bolted onto the chrome plated countercell (please excuse the fingerprint). Collimation of the objective is through a "push-pull" system. The counter cell is bolted to the tube with low profile bolts which do not intrude into the light path:

Here is the fully multicoated Istar 150mm (clear aperture) F/12 objective in it's cell. The reference number engraved into the bezel is actually Istar's Zip code in Page, Arizona !. Later Istar objectives were individually numbered but this is one of their earlier ones, as confirmed by Ales Krivanek, Istar's founder, when I asked him about it's history:

The next 2 photos show the back of the chrome plated counter cell with the manufacturer and model details engraved into it:

The Istar objective dust cap is a rather innovative design comprising of a sandwich of CNC alloy and high density foam. By adjusting the two small chrome nuts, the foam is squeezed slightly and presses against the inside walls of the long CNC dew shield holding the cap in place and keeping dust and light out:

Finally here is a picture I took a little while back showing the big Istar alongside my Skywatcher ED120 and Vixen ED102SS refractors. A 6" F/12 is a big scope !!!

[Astro_Baby]

A really beautiful scope....I am green with envy

[russ.will]

It is a thing of beauty. I love the matte black with chrome highlights, which put me in mind of some of the more tasteful Harley Davidsons and yes; that is an oxymoron. Maybe it's a man thing, if I may be so misogynistic. I also love detail being machined into components for the hell of it. No need to do it what-so-ever, but boy does it look good.

I wonder if I'd need the counter weight on my Minitower v2.0 when I pick it up? 

Seeing it dismantled (and thanks for the detailed piccies btw) I'm surprised how short the lens shade is. Surely they didn't make that scope and then worry about the overall length? That horse had long since bolted!

Not that I expect many of these will be carrying imaging payloads, but I note from that they can't machine a flat on a Crayford. Unlike a dozen a dime SW, you'd think twice before taking a whetstone to that finish though.

Russell

[John]

Thanks Mel and Russell

I agree Russell, the Crawmach focuser is not a Feathertouch or Moonlite . Crawmach were not around for long making these things. Now the Istars are supplied with William Optics, Moonlite or Feathertouch focusers depending on the purchasors choice / budget. Mine was bought used so I've got what came with it. 

Perhaps because the focuser US made it uses rather large set screws to press the compression rings - the 2" fitting one is M8 I think !

In many ways the scope is about the most illogical purchase I've made in the hobby. It's turned into a long term project to get the mounting arrangements sorted properly, mostly because I can't throw £1K plus at the problem

One day it will be sorted though

[triton1]

A beautiful scope it is John but it's absolutley huge!,how long is it with dew shield 6ft?

[John]

A beautiful scope it is John but it's absolutley huge!,how long is it with dew shield 6ft?

It's around 6 foot 4 inches with the diagonal.

[Qualia]

Aye, it's gorgeous, John. I imagine the views are spell binding, especially of the Moon and planets. Is the Vixen 102 the finder ?

Anyway, for us mere mortals, to get some idea of proportion this is a photo of John (in his favourite astro-coat ) getting ready for this evening's Io shadow and GRS transit:

[John]

Rob, you are a naughty person !!

That one is an F/15 so even longer !

[Joves]

The sheer size of that thing is incredible!

Lovely scope, John.

[Moonshane]

Which one is the Istar again John? :0)

Superb scope indeed in every way.

[alan potts]

A beautiful looking scope John and I imagine at F12 not too much in the way of CA to worry about which is what always put me off the shorter Bresser models. The F15 looks like one to pire mount and use from a frist floor window or with stilts.

Alan

[chiltonstar]

That's what I call a scope!

What about a Lord Rosse mounting? That was for a 6 footer, although aperture rather than length presumably.

Chris

[swamp thing]

Thats a big beast for sure. Are you bringing it to SGLX John? 

[Marki]

Lovely pics John - makes me feel a bit wistful I sold my f10. Until I remember just how long it was again, and how much of a pain to get on the mount! Still, my f10 gave me the best views of Mars I've ever had... . The Crawmach focusser is distinctly nicer than the really basic focusser that mine had.

Is yours getting much use at the moment?

[John]

It's not getting much use unfortunately Mark, due to delays in getting a proper mounting solution plus recently a back injury getting in the way

@ Steve: I suspect I won't have the mounting sorted by SGLX so I'll take my 12" dob there.

[jam1e1]

How on earth did that get delivered??! Can't imagine would fit in many vehicles!

Really nice scope though!

[The Flinty Fox]

If Darth Vader had a scope .

But seriously it must be amazing to look through.

I'll be happy with the vixen.

Paul.

[John]

How on earth did that get delivered??! Can't imagine would fit in many vehicles!

Really nice scope though!

Thanks.

The scope has a 7 foot packaging case that just fits in my Volvo Estate with the rear seats folded flat and the passenger front seat moved right forward.

[Rainmaker]

Love the big Istar Scope !!! I had a Perseus 150mmF10 thanks for sharing the pictures.  They are certainly built like a tank.  Mine had the Moonlite focuser which I really liked.

(I don't have the same feelings toward Dan Crawford and Crawmach Machining though    ............ good riddance)

[John]

Love the big Istar Scope !!! I had a Perseus 150mmF10 thanks for sharing the pictures.  They are certainly built like a tank.  Mine had the Moonlite focuser which I really liked.

(I don't have the same feelings toward Dan Crawford and Crawmach Machining though    ............ good riddance)

Thanks Rainmaker

While the focuser on the Istar is not as good as the Moonlite on my ED120 it's a perfectly decent 2 speed crayford and just as good as some I've used from William Optics, Skywatcher and others. It does it's job competantly including holding big eyepieces in the heavy Istar 2" diagonal even when the scope is pointing upwards.

The worst crayford I've used was the UK made Orion Optics one I'm afraid   

[Mikeennamorato]

Late to the party, but... How are the optics on these Istars? Thinking about getting a shorter model myself, problem is I simply have not heard a whole lot about them. 

She's a looker for sure. 

[Guest]

Great looking traditional telescope.What is it mounted on?

[John]

Great looking traditional telescope.What is it mounted on?

Nothing at the moment - sorting a suitable mount out has been a significant challenge !

It's a sort of long term project. The scope came up at a price that I could not refuse so I went for it knowing that it would throw up all sorts of mounting issues, which it has. I'll get it sorted out one day but I'd like to do that without having to invest more than the scope cost in a mount, if possible

[John]

Late to the party, but... How are the optics on these Istars? Thinking about getting a shorter model myself, problem is I simply have not heard a whole lot about them. 

She's a looker for sure. 

From the limited viewing I've done with it the optics seem very good. I had no trouble splitting a 1 arc second double star with it and that was using a far from stable mount. It shows some chromatic abberration as you would expect but it's well controlled.

Here is a review of the F/10 version of this scope by Neil English:

http://neilenglish.net/adentures-with-the-istar-6-f10-achromat/