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Istar 150MM Objective

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#1 KarlL

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Posted 01 February 2013 - 02:25 PM

I understand that this is not ATM forum, but a number of you do build or refurbish, so here it goes. Does anyone have experience with the Istar 150mm f/15 objective? This is only a pipe dream at this time, and I will probably go for the AstroTelescope in the end, but I am somewhat interested in building a refractor similar to the one in Richard Berry's book.

Regards,

Karl

#2 neotesla

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Posted 01 February 2013 - 02:47 PM

I can't remember the details, but a member here plyscope, did a build with an Istar 6" lense... and I can't find the thread with a quick search. He had a detailed thread on how he did it and what his impressions of the lense were as well.

#3 neotesla

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Posted 01 February 2013 - 02:50 PM

Sorry it was an 5" f12 from istar, he had a 6" f15 D&G...

http://www.cloudynig...4572197/page...

#4 Gord

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Posted 01 February 2013 - 03:00 PM

Is it the classic achro lens? There are quite a number of us here that have built using those lenses at F10/12/15 in the 6" size. Some others have done other sizes too. I like mine for what it is and it was great value when I got it. Very few reports that I have seen on the R-series though if that was what you were looking at.

Clear skies,

#5 jhfenimore

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Posted 01 February 2013 - 03:52 PM

Don't know what your timeline is for building the telescope. I've just ordered an Istar 6" F15 achro, and plan to build a folded refractor on a dob mounting. Hoping it will be a stable alternative to my shakey (at high power) 4" apo on an alt-az mount. Visual observing only, mostly doubles, clusters, and solar system objects. Have been advised by large apo refractor users far more experienced than myself that the color shouldn't be much of a problem at F15.

Probably won't have the project completed until late spring. Until then, may not be able to give you any useful information.

Jack

#6 Rutilus

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Posted 01 February 2013 - 04:31 PM

I'm building an Istar 150mm f/15 Achro at the moment. I collect the lens tomorrow morning (Saturday).
I'm building the tube so that it splits into two sections for storage and transportation.
Heres a couple of pictures of the jointing section.

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#7 Rutilus

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Posted 01 February 2013 - 04:32 PM

Jointing section.

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#8 Kevin Barker

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Posted 01 February 2013 - 04:50 PM

Hi
I tried a similar design a few years ago with a Zeiss AS63/840 objective using two aluminium pipes of different diameters and a turned plastic fitting. Gary Beal from hamilton , NZ owned an original astro special version and mine was a poor mans clone. gary helped with the project.

It worked but did struggle with low temperature as the plastic and aluminium expanded differently.

Andy Dodson in Taranaki NZ now owns this wee scope now.

I think he uses it for solar observation.

Good luck with using MDF, I imagine it should be stable enough.

There is a review somewhere of a 6 inch f-15 istar achromat. It rates well around 1/6th PV and the owner is very happy with the visual performance of the long fous lens.

My twin brother Phil Barker is currently grinding a 148 mm doublet(littrow/clark type) from two pre generated blanks he has acquired from a professional telescope maker's estate.

I wish him luck , he also needs to make a cell, it is f-16,

The shot is my el cheapo 5 inch f-6.5 Barkonian refractor......

Kevin

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#9 Sean Cunneen

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Posted 01 February 2013 - 04:51 PM

I bought one and built an OTA when Istar first hit the market. The lens was good and performed well for the price. They have risen signifigantly in price since I bought mine. I think I paid $360 at the time. When Surplus Shed started to offer the Jaeger's lens, I bought one of those. I put both up for sale and the Istar sold in hours, so I have stayed with the Jaegers.

In terms of performance the lens was decent and on some nights, exquisite. I noticed the Istar cell had a tendency to pinch the glass and I found I had to keep an eye on the cell tension. The coatings were very good. I feel my Jaeger's is sharper but because it's uncoated, the views of DSO's are dimmer but with sharper stars.

I hope in the 3 years since I bought mine the quality has improved and that Istar lenses will rival those from much more expensive sources.

You can see my original build here:

Istar build "Jill"

#10 plyscope

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Posted 01 February 2013 - 04:57 PM

I have the 5" f12 lens from Istar, it is a great lens. Neotesla shared the link to the thread about the construction above.

There is a picture here.


Here is a link to an older thread about my 6" f15 D & G.

web page

A picture is here.

I encourage you to build a refractor with an Istar or D & G lens. It is a fun project, you will learn a lot and have a wonderful telescope at the end. :)

#11 John Jarosz

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Posted 02 February 2013 - 09:07 AM

I built a scope from the 6" F5 Istar objective. I felt f 15 was way too long a scope for me, but I understand why you'd want that type of scope. The objective cell is the same. You'll need a flange or some thickness. in the tube to attach the cell at that end. You can see the details of my build by following the link in my sig line. I am very happy with the Istar quality and the scope I ended up with.

John.

#12 Rutilus

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Posted 02 February 2013 - 02:54 PM

Today I collected my Istar lens, after waiting around 3 weeks for delivery from the U.S.A. The lens also came with a report.
Also picked-up a massive equatorial mount, which will be mounted onto a taller pier. The mount head weighs around 55
pounds, the short reflector pier that came with it weighs even more.

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#13 Rutilus

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Posted 02 February 2013 - 02:57 PM

Sorry about the poor quality photo of the mount, I intend to take some better photo's during daylight.
For scale my Vixen GP mount is included, in the flesh the equatorial is way more bigger than the Vixen.

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#14 KarlL

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Posted 02 February 2013 - 09:16 PM

Due to its length, I've shelved the idea of building a scope. My wife, who is otherwise very supportive, has brought me back to reality. An f/15 is right now out of the question.

But I can still dream...

Regards,

Karl

#15 timwetherell

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Posted 03 February 2013 - 09:04 PM

I bought a ISTAR 9" f9 a while back and was very happy with both it and the customer service :)

#16 Meep_Esq

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Posted 03 February 2013 - 10:30 PM

Due to its length, I've shelved the idea of building a scope. My wife, who is otherwise very supportive, has brought me back to reality. An f/15 is right now out of the question.

But I can still dream...


Hmm! I think I like the reality where you get the long lens and fold it with a flat and end up with a superb telescope in a more convenient-to-use package :)

#17 KarlL

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Posted 04 February 2013 - 10:10 AM

Vaughn -

I'm actually considering that as a long-term project. I'm not sure as to how to design it at this point. It can't be difficult. However, it would be, for me, very expensive. It would probably be double- or triple-folded.

I'm at the point that I probably should start asking questions on the ATM forum.

Regards,

Karl

#18 plyscope

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Posted 04 February 2013 - 04:52 PM

Here is a link to a German pdf with pictures and details of folded refractors. Might give you some ideas. It's about 3.2Mb.

Faltrefraktoren pdf

#19 Paul C-I

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Posted 04 February 2013 - 06:06 PM

Andy,
Very interesting and thanks for the link.
I too am possibly considering a single fold for my forth coming Istar 8" F12 R35 lens. Have couple of months to consider various designs.
Paul

#20 Kevin Barker

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Posted 05 February 2013 - 04:04 AM

HI Vaughn
Is your Newtonian really a 200 mm f-13. I guess it can be a spherical mirror and not need parabolising at this focal length??

I used a friends 200 mm f-10 a few years ago and it was amazing when collimated.

Kevin
Auckland, New Zealand(36 degrees 42 min South)
200 mm f-6 Newtonian(homemade mount and ota Parks optics), 300 mm f 5 Newtonian(brock optics), 150 mm f-4 Newtonian(Nanckivell optics), Zeiss AS 80/840, semi apochromatic refractor, Zeiss APQ 130/1000 apochromatic refractor, 127/830 achromatic refractor
10 X 70 Fuji FMT-SX, Garrett 20 X 110 binoculars....

Zeiss, AP, Televue eyepieces.

#21 Meep_Esq

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Posted 05 February 2013 - 05:22 PM

HI Vaughn
Is your Newtonian really a 200 mm f-13. I guess it can be a spherical mirror and not need parabolising at this focal length??

I used a friends 200 mm f-10 a few years ago and it was amazing when collimated.


Yes it is. And yep, it has a spherical figure, less complicated to test, a little more forgiving of my skills in manufacture, and less hard on simpler (or inexpensive) EPs, etc... :-) For me, it's the solution to owning a lovely, long focus, big achromat, at a fraction of the cost.






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