Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> Refractors

Pages: 1 | 2 | (show all)
Kunama
professor emeritus


Reged: 10/22/12

Istar best achromat for big refractor build ?
      #6070090 - 09/08/13 07:03 PM

I am planning to build a large refractor in the future. I previously had a 6"F10 Istar which was excellent so will most likely go that way again.
I wonder if there are any other brands of objectives that can match them for price/quality?

We don't have much choice here in Australia so hopefully some European or USA members can chime in here.

I am considering 8" F8 or larger.

Many thanks in advance.


Post Extras: Print Post   Remind Me!   Notify Moderator  
timps
sage


Reged: 02/24/13

Re: Istar achromats best way to go for big scope ? new [Re: Kunama]
      #6070336 - 09/08/13 10:01 PM

Why not a reflector for a big scope?

Post Extras: Print Post   Remind Me!   Notify Moderator  
Kunama
professor emeritus


Reged: 10/22/12

Re: Istar achromats best way to go for big scope ? new [Re: timps]
      #6070346 - 09/08/13 10:13 PM

I will be building a reflector later as well but am really more interested in the refractors.

Post Extras: Print Post   Remind Me!   Notify Moderator  
plyscope
Pooh-Bah


Reged: 11/23/06

Loc: Perth, West Australia
Re: Istar achromats best way to go for big scope ? new [Re: Kunama]
      #6070357 - 09/08/13 10:19 PM

I've considered this myself and I think Istar is probably the best value option other than a reflector.

There is the APM 203/1800 with TMB designed lens that would be wonderful but at a much greater cost.

web page

My conclusion is to do the ATM thing with an 8" lens from Istar or else go for a high end ATM dob (Royce, Zambuto, Lockwood etc.) 10 or 12" for similar cost.

Before any of that I need to catch up on my current projects.


Post Extras: Print Post   Remind Me!   Notify Moderator  
jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Istar achromats best way to go for big scope ? new [Re: Kunama]
      #6070363 - 09/08/13 10:21 PM

Nah. I'd say a premium Dob is the best way to go for a big scope. And if we're talking only refractors, I'd say a top quality large apochromat (TEC, A-P, APM/LZOS, etc.) would be the best option. Years of proven quality. Low depreciation/solid and liquid investment. Decent availability, etc. But not cheap.

[note: post edited by FirstSight]

Regards,

Jim

Edited by FirstSight (09/09/13 11:16 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
plyscope
Pooh-Bah


Reged: 11/23/06

Loc: Perth, West Australia
Re: Istar achromats best way to go for big scope ? new [Re: jrbarnett]
      #6070382 - 09/08/13 10:35 PM

One thing that sways me towards refractors rather than reflectors is that there is no local facility for re-coating mirrors. The only option is shipping the mirror to the other side of Australia and back (>3000km each way). This adds to the future running costs. Refractors can be virtually maintenance free with due care.

I have a decent 8" f6 mirror that needs a re-coat but it will cost over $300 so it is on hold for now. I can buy a new GSO mirror for that or a new Royce mirror for under a $1000 delivered.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Kunama
professor emeritus


Reged: 10/22/12

Re: Istar achromats best way to go for big scope ? new [Re: plyscope]
      #6070567 - 09/09/13 01:16 AM

I am hoping to get a look through the Oddie II refractor at some stage, I have already had a good look at the lens in it and it certainly looks the goods.
It is more of a scope building exercise and an achromat is more than sufficient, I have no need for TECs or other APOs, my TAK TSA is fine for those purposes. Reflectors really aren't my thing (although I intend to build one at some stage).



Post Extras: Print Post   Remind Me!   Notify Moderator  
mikey cee
Postmaster
*****

Reged: 01/18/07

Loc: bellevue ne.
Re: Istar achromats best way to go for big scope ? new [Re: Kunama]
      #6070585 - 09/09/13 01:39 AM

Matt as a person living the dream of using a larger Istar refractor my answer would be a definite yes. At 9" and larger there aren't many options. If you could only have been with me last night after midnight. These lenses are really more than just good.

[note: Post Edited by FirstSight]

Mike

Edited by FirstSight (09/09/13 11:17 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Messyone
sage


Reged: 05/02/12

Loc: Down Under
Re: Istar achromats best way to go for big scope ? new [Re: mikey cee]
      #6070618 - 09/09/13 02:48 AM

Matt,
An 8" would be have been my choice if I had a mount to take it. As you know I'm doing a 6" f12.
Locally available is 203mm 3mm thick drawn aluminium pipe that would hold an 8" beautifully.
I would go for as long an FL as you could and would get an Istar R 35 f12 objective would be the one I would choose.
Why oh why when you ask which refractor objective to get the reply from some is...get a dob....
Matt


Post Extras: Print Post   Remind Me!   Notify Moderator  
Kunama
professor emeritus


Reged: 10/22/12

Re: Istar achromats best way to go for big scope ? new [Re: Messyone]
      #6070653 - 09/09/13 03:47 AM

Hey Matt, I thought posting in the refractor forum would have been sufficient but have amended the thread title.
I have the enormous Gaunt Mount c1865 that will easily carry anything I can build, I'll look into the 8" lens. Looks like Istar has no competition as I think the others only sell complete scopes.
I'm trying to finish the other refractors so I can start the big project.


Post Extras: Print Post   Remind Me!   Notify Moderator  
James Ling
sage
*****

Reged: 09/18/10

Loc: Singapore
Re: Istar achromats best way to go for big scope ? new [Re: Kunama]
      #6070771 - 09/09/13 07:10 AM

Hi Matt...

You should go for the Istar 8" F12 R30 lens....
If your mount can take it........

Regards

James Ling


Post Extras: Print Post   Remind Me!   Notify Moderator  
plyscope
Pooh-Bah


Reged: 11/23/06

Loc: Perth, West Australia
Re: Istar achromats best way to go for big scope ? new [Re: Kunama]
      #6070773 - 09/09/13 07:12 AM

Hi Matt

You can buy the APM TMB lens in cell only however it is 2850 Euros.

web page

There is D & G but only in f12 or longer.

web page

Then there is Barride Optics from China. I would expect them to be less expensive than Istar and I have no direct experience.

web page

Other than those you are left with waiting for a secondhand lens to pop up on the classifieds or Astromart.


Post Extras: Print Post   Remind Me!   Notify Moderator  
opticsguy
sage


Reged: 02/02/09

Loc: Washington State
Re: Istar achromats best way to go for big scope ? new [Re: plyscope]
      #6071049 - 09/09/13 11:11 AM

Have you considered custom made? I kind of remember an optician; Ross Optical? Not sure if that is the correct name.

Post Extras: Print Post   Remind Me!   Notify Moderator  
t.r.
Post Laureate
*****

Reged: 02/14/08

Loc: Upstate NY
Re: Istar achromats best way to go for big scope ? new [Re: opticsguy]
      #6071126 - 09/09/13 11:43 AM

RF Royce will make large achromats...oil spaced too!

Royce


Post Extras: Print Post   Remind Me!   Notify Moderator  
tomharri
sage
*****

Reged: 09/19/08

Loc: USA
Re: Istar achromats best way to go for big scope ? new [Re: t.r.]
      #6071147 - 09/09/13 11:51 AM

That APM 203 f/9 really looks tempting. But after my results with the 127 f/8 R30, will never do a basic achromat again. The blue fringe at 250x on the planets is almost nothing. About the same as a Carton 100/1300.
The 'R' works.


Post Extras: Print Post   Remind Me!   Notify Moderator  
roscoe
curmudgeon
*****

Reged: 02/04/09

Loc: NW Mass, inches from VT
Re: Istar achromats best way to go for big scope ? new [Re: jrbarnett]
      #6071384 - 09/09/13 02:03 PM

[post edited by FirstSight]

Edited by FirstSight (09/09/13 11:17 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
dlapoint
scholastic sledgehammer


Reged: 08/18/03

Loc: Moncton NB Canada
Re: Istar achromats best way to go for big scope ? new [Re: roscoe]
      #6071807 - 09/09/13 06:01 PM

I'd love the 8" f8.8 myself but have not the mount. I'm now looking at the 5" f12 r30

Post Extras: Print Post   Remind Me!   Notify Moderator  
Kunama
professor emeritus


Reged: 10/22/12

Re: Istar achromats best way to go for big scope ? new [Re: dlapoint]
      #6072043 - 09/09/13 08:25 PM

Thanks everyone for the suggestions, I will get to work on current 80F15 scopes, get them finished and then get onto the big one. Looks like the 8"F8.8 might be the one.
The APM looks tempting but I think the $$$ might be vetoed by the Finance Minister.


Post Extras: Print Post   Remind Me!   Notify Moderator  
RGM
scholastic sledgehammer
*****

Reged: 09/15/03

Loc: Burks Falls, Ontario, Canada
Re: Istar achromats best way to go for big scope ? new [Re: dlapoint]
      #6072112 - 09/09/13 08:58 PM

Quote:

I'd love the 8" f8.8 myself but have not the mount. I'm now looking at the 5" f12 r30




Great scope, rides very well on my G11. Works well with all the eyepieces I have. Depth of focus on the f12 is great for double star work.


Post Extras: Print Post   Remind Me!   Notify Moderator  
RGM
scholastic sledgehammer
*****

Reged: 09/15/03

Loc: Burks Falls, Ontario, Canada
Re: Istar achromats best way to go for big scope ? new [Re: roscoe]
      #6072120 - 09/09/13 09:02 PM

Post edited by FirstSight

Edited by FirstSight (09/09/13 11:17 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
FirstSightModerator
Duke of Deneb
*****

Reged: 12/26/05

Loc: Raleigh, NC
Re: Istar achromats best way to go for big scope ? new [Re: RGM]
      #6072128 - 09/09/13 09:07 PM

This thread is now RE-OPEN for posting comments. Constructive, respectful critiquing of Istar achromats is welcome, provocatively disrespectful comments toward same or other members, not so much.

Edited by FirstSight (09/09/13 10:21 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
dlapoint
scholastic sledgehammer


Reged: 08/18/03

Loc: Moncton NB Canada
Re: Istar achromats best way to go for big scope ? new [Re: RGM]
      #6073762 - 09/10/13 07:16 PM

Bob, doubles and planetary viewing is what I want the scope for. Where did you buy yours?

Post Extras: Print Post   Remind Me!   Notify Moderator  
A. Viegas
scholastic sledgehammer
*****

Reged: 03/05/12

Loc: New York City/ CT
Re: Istar achromats best way to go for big scope ? new [Re: RGM]
      #6073816 - 09/10/13 07:48 PM

Just a generic question, but why not an 8" F16 for super planetary type work? is the mounting issues of such a long tube the main problem? FL would be like 3200, so not too much in terms of magnification... Just wondering why nobody builds longer FL than F12 generally?

Al


Post Extras: Print Post   Remind Me!   Notify Moderator  
David PavlichAdministrator
Transmographied
*****

Reged: 05/18/05

Loc: Mandeville, LA USA
Re: Istar achromats best way to go for big scope ? new [Re: A. Viegas]
      #6073915 - 09/10/13 08:46 PM

Quote:

Just a generic question, but why not an 8" F16 for super planetary type work? is the mounting issues of such a long tube the main problem? FL would be like 3200, so not too much in terms of magnification... Just wondering why nobody builds longer FL than F12 generally?

Al




Think about the mount you'd need for that 8" lever. And think about where you'd house it. All big stuff.

David


Post Extras: Print Post   Remind Me!   Notify Moderator  
beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Istar achromats best way to go for big scope ? new [Re: David Pavlich]
      #6073985 - 09/10/13 09:36 PM Attachment (43 downloads)

Good choice the Isatr's are and Matt I look forward to what ever you decide on .
If I had a mount like your beautiful 'Gaunt' I would definatly look at the 7.1 inch f8 or f12 slim , R35 by Istar and if these are as good as I hear you will be right by one of these .
One of these would keep the weight down as well .

By the way here is a shot of Venus taken last Saturday night in my Istar 127mm f8 achro , this is raw , no work except a small zoom and crop with sizing for CN's .
Great objectives .

Brian.

Edited by beanerds (09/10/13 09:39 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Kunama
professor emeritus


Reged: 10/22/12

Re: Istar achromats best way to go for big scope ? new [Re: beanerds]
      #6074000 - 09/10/13 09:50 PM

I think the 8" F9 is about the biggest I would want to put on the mount, although no doubt it will carry much more weight, I still need to be able to move the thing around. At the moment I can carry the mount but the pier needs a trolley. I am guessing the all up weight will be about 150Kg or 330 lbs. When complete I hope to take the lot to starparties on a custom cradle in a trailer.

Post Extras: Print Post   Remind Me!   Notify Moderator  
RGM
scholastic sledgehammer
*****

Reged: 09/15/03

Loc: Burks Falls, Ontario, Canada
Re: Istar achromats best way to go for big scope ? new [Re: dlapoint]
      #6074543 - 09/11/13 08:11 AM

Quote:

Bob, doubles and planetary viewing is what I want the scope for. Where did you buy yours?




Derek, I purchased mine from Canadian Telescopes. At the time they were having a sale. If you contact Mike at Istar, you might find they have a few overstocked scopes at a sale price. I believe they will cover a portion of the shipping from Florida.


Post Extras: Print Post   Remind Me!   Notify Moderator  
dan_h
Carpal Tunnel


Reged: 12/10/07

Re: Istar achromats best way to go for big scope ? new [Re: RGM]
      #6074615 - 09/11/13 09:08 AM

Quote:

Quote:

Bob, doubles and planetary viewing is what I want the scope for. Where did you buy yours?




Derek, I purchased mine from Canadian Telescopes. At the time they were having a sale. If you contact Mike at Istar, you might find they have a few overstocked scopes at a sale price. I believe they will cover a portion of the shipping from Florida.




Istar currently has an ad on AM for a sale of overstock items. There are a couple of nice sized scopes available at a decent discount.

dan


Post Extras: Print Post   Remind Me!   Notify Moderator  
dlapoint
scholastic sledgehammer


Reged: 08/18/03

Loc: Moncton NB Canada
Re: Istar achromats best way to go for big scope ? new [Re: dan_h]
      #6075020 - 09/11/13 12:44 PM

thanks guys, I will look into it

Post Extras: Print Post   Remind Me!   Notify Moderator  
rwiederrich
Goldfinger
*****

Reged: 11/17/05

Loc: Always Dark skies of Belfair W...
Re: Istar achromats best way to go for big scope ? new [Re: A. Viegas]
      #6075508 - 09/11/13 04:43 PM

Quote:

Just a generic question, but why not an 8" F16 for super planetary type work? is the mounting issues of such a long tube the main problem? FL would be like 3200, so not too much in terms of magnification... Just wondering why nobody builds longer FL than F12 generally?

Al




I wouldn't say that...I had a hand in builing a 6"f/15 and I build my 10"f/15.

Rob


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Istar achromats best way to go for big scope ? new [Re: rwiederrich]
      #6075530 - 09/11/13 04:57 PM

Quote:

I wouldn't say that...I had a hand in builing a 6"f/15 and I build my 10"f/15.

Rob




Rob:

Who made the lens for your 10 inch F/15? You didn't make that yourself did you?

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Istar achromats best way to go for big scope ? new [Re: beanerds]
      #6075534 - 09/11/13 05:00 PM

Interesting photo.

I am not seeing the blue-red/orange atmospheric refraction at the bottom and top of Venus that I see with my reflectors (and apo's).

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
Messyone
sage


Reged: 05/02/12

Loc: Down Under
Re: Istar achromats best way to go for big scope ? new [Re: Jon Isaacs]
      #6076348 - 09/12/13 04:39 AM

Quote:

Interesting photo.

I am not seeing the blue-red/orange atmospheric refraction at the bottom and top of Venus that I see with my reflectors (and apo's).
Jon



Jon thats because the Istar objectives are that good...really. I have a great Synta 6" f8 but am in the process of building a 6" f12 Istar scope. f12 is a long as I could go with my mount and tripod.
Rob I think I should join your refractor group.
Matt


Post Extras: Print Post   Remind Me!   Notify Moderator  
mikey cee
Postmaster
*****

Reged: 01/18/07

Loc: bellevue ne.
Re: Istar achromats best way to go for big scope ? new [Re: Messyone]
      #6076714 - 09/12/13 10:37 AM

Matt Istars are more than good...they are great. But you will still see atmosheric dispersion or aberration. I do. Just wanted to set the record straight. Mike

Post Extras: Print Post   Remind Me!   Notify Moderator  
Kunama
professor emeritus


Reged: 10/22/12

Re: Istar achromats best way to go for big scope ? new [Re: mikey cee]
      #6077457 - 09/12/13 05:24 PM

Thank you all for the feedback, I have decided to go with the Istar objectives and once underway will do a thread in the ATM forum.

Post Extras: Print Post   Remind Me!   Notify Moderator  
beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Istar achromats best way to go for big scope ? new [Re: Jon Isaacs]
      #6078242 - 09/13/13 05:46 AM Attachment (21 downloads)

what are you suggesting Jon ? , here is the original , sized for CN's of course .
Brian.
Quote:

Interesting photo.

I am not seeing the blue-red/orange atmospheric refraction at the bottom and top of Venus that I see with my reflectors (and apo's).

Jon




Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | (show all)


Extra information
22 registered and 31 anonymous users are browsing this forum.

Moderator:  Scott in NC, FirstSight, panhard, star drop 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 1890

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics