Jump to content


Photo

Which mount for large refractor ?

  • Please log in to reply
36 replies to this topic

#1 PhilCo126

PhilCo126

    Gemini

  • -----
  • Posts: 3239
  • Joined: 14 Jan 2005
  • Loc: coastline of Belgium

Posted 11 May 2011 - 04:03 AM

We're trying to find out which mount to use to hold a 20 kilograms refractor for a small observatory ( outreach observational use, occasional astro-photography )... without getting under-mounted :question:
Losmandy G-11 can hold 35 kg
CGE-Pro can hold 45 kg

#2 gillmj24

gillmj24

    Aurora

  • *****
  • Posts: 4911
  • Joined: 06 Dec 2005
  • Loc: PA

Posted 11 May 2011 - 06:44 AM

A large refractor needs substantially more mount than the equivalent weight (or even a heavier) short tube SCT.

I've seen a C14 on a G 11 but I wouldnt put a 50 pound "large" (meaning long) refractor on one.

#3 Eddgie

Eddgie

    Voyager 1

  • *****
  • Posts: 12675
  • Joined: 01 Feb 2006

Posted 11 May 2011 - 08:20 AM

Losmandy Titan or something similar at the LEAST.

Not even sure the Titan will hold a 20 KG refractor still even though it is rated at 50KG load.

Some depends on the length of the refractor you are mounting.

If it is much more than a couple of meters long, you will most likely need a steel pier.

Titan would likely be your best bet though if you are cost concious.

#4 alpal

alpal

    Soyuz

  • -----
  • Posts: 3663
  • Joined: 15 Jun 2009
  • Loc: Melbourne Australia.

Posted 11 May 2011 - 08:26 AM

What is the focal length of this refractor
& the diameter of the objective?

#5 David Pavlich

David Pavlich

    Transmographied

  • *****
  • Administrators
  • Posts: 27509
  • Joined: 18 May 2005
  • Loc: Mandeville, LA USA

Posted 11 May 2011 - 08:27 AM

Losmandy Titan or something similar at the LEAST.

Not even sure the Titan will hold a 20 KG refractor still even though it is rated at 50KG load.

Some depends on the length of the refractor you are mounting.

If it is much more than a couple of meters long, you will most likely need a steel pier.

Titan would likely be your best bet though if you are cost concious.


I don't know...a Tak TOA150 is around 40-45lbs and I wouldn't hesitate to put it on my MI250.

David

#6 M13 Observer

M13 Observer

    Viking 1

  • -----
  • Posts: 991
  • Joined: 09 Dec 2006

Posted 11 May 2011 - 09:22 AM

We're trying to find out which mount to use to hold a 20 kilograms refractor for a small observatory ( outreach observational use, occasional astro-photography )... without getting under-mounted :question:
Losmandy G-11 can hold 35 kg
CGE-Pro can hold 45 kg


AP900 on a steel or concrete pier.

#7 Eddgie

Eddgie

    Voyager 1

  • *****
  • Posts: 12675
  • Joined: 01 Feb 2006

Posted 11 May 2011 - 10:03 AM

Oh, I think the MI-250 would be a nice choice, but it is no longer made, and the cheapest MI mount available today is over $12000.

These mounts to me also kind of fall into the "Custom" mount catagory because often they are built to order.

The Titan is half the price and is generally available.

And for someone in Europe that will have to pay import duties on top of the purchase price, I think that the MI mount can be a pricy issue.

But the OP really didn't give any details other than weight, and no information on budget or anything.

So the only thing we can do is make unqualified noise. We really don't know what his requirements and budget are.

#8 PhilCo126

PhilCo126

    Gemini

  • -----
  • Posts: 3239
  • Joined: 14 Jan 2005
  • Loc: coastline of Belgium

Posted 11 May 2011 - 01:11 PM

sorry, for those who didn't follow the refractor topic, it's about this large achromatic refractor:
Fraunhofer achromatic 203 mm / 1800 = f/8.8 (20 kilogram)

http://www.apm-teles...666&bildid=1651

#9 skybsd

skybsd

    Skylab

  • *****
  • Posts: 4281
  • Joined: 01 Feb 2008

Posted 11 May 2011 - 01:54 PM

sorry, for those who didn't follow the refractor topic, it's about this large achromatic refractor:
Fraunhofer achromatic 203 mm / 1800 = f/8.8 (20 kilogram)

http://www.apm-teles...666&bildid=1651


What is your budget?

Regards,

skybsd

#10 M13 Observer

M13 Observer

    Viking 1

  • -----
  • Posts: 991
  • Joined: 09 Dec 2006

Posted 11 May 2011 - 02:56 PM

sorry, for those who didn't follow the refractor topic, it's about this large achromatic refractor:
Fraunhofer achromatic 203 mm / 1800 = f/8.8 (20 kilogram)

http://www.apm-teles...666&bildid=1651


1.8 metre?!? AP1200 or Paramount.

#11 gillmj24

gillmj24

    Aurora

  • *****
  • Posts: 4911
  • Joined: 06 Dec 2005
  • Loc: PA

Posted 11 May 2011 - 03:32 PM

"PS I forgot to say I don't want to spend more than $750 on the mount"

I love it when they say that ;)

#12 alpal

alpal

    Soyuz

  • -----
  • Posts: 3663
  • Joined: 15 Jun 2009
  • Loc: Melbourne Australia.

Posted 11 May 2011 - 06:12 PM

"PS I forgot to say I don't want to spend more than $750 on the mount"

I love it when they say that ;)


Where did Phil say that?
$750 ????? :shocked:

#13 Eddgie

Eddgie

    Voyager 1

  • *****
  • Posts: 12675
  • Joined: 01 Feb 2006

Posted 11 May 2011 - 07:09 PM

Well, some of the pictues in the links you sent show them on a CGE.

If it were on a sturdy pier, maybe a CGE or G11 head would work.

Being in a dome would mean that you don't have as much issue with wind.

#14 wz2

wz2

    Most Boring Astronomer...

  • -----
  • Posts: 267
  • Joined: 30 Jul 2010

Posted 11 May 2011 - 08:16 PM

AP-3600

"I say we nuke the entire site from orbit - it's the only way to be sure"

Chris

#15 alpal

alpal

    Soyuz

  • -----
  • Posts: 3663
  • Joined: 15 Jun 2009
  • Loc: Melbourne Australia.

Posted 11 May 2011 - 09:02 PM

AP-3600

"I say we nuke the entire site from orbit - it's the only way to be sure"

Chris


Yes the AP 3600 would definetly work but
at $26,000 it might be above their budget.

see my thread:
http://www.cloudynig...5/o/all/fpart/1

#16 gillmj24

gillmj24

    Aurora

  • *****
  • Posts: 4911
  • Joined: 06 Dec 2005
  • Loc: PA

Posted 11 May 2011 - 09:13 PM

Phil didn't say that but there's often threads about I want to do this that and everything else and not pay more than ____

#17 alpal

alpal

    Soyuz

  • -----
  • Posts: 3663
  • Joined: 15 Jun 2009
  • Loc: Melbourne Australia.

Posted 11 May 2011 - 10:34 PM

Phil didn't say that but there's often threads about I want to do this that and everything else and not pay more than ____


I spoke to a well known astronomer here in Melbourne
who claims he once made his own mount (30 years ago)
with a washing machine motor to drive it.
He actually got it to track for 5 minute frames
using drift alignment & no guiding.
It cost him almost nothing as he had a machine shop
to build it in.

#18 AntarcticDave

AntarcticDave

    Mariner 2

  • -----
  • Posts: 288
  • Joined: 03 Feb 2009
  • Loc: Denver, CO

Posted 12 May 2011 - 11:58 AM

If you don't need a GOTO mount you might consider an Optic-Craft mount - something like a model 5 would most likely suffice.
http://www.opticcraf...copemounts.html

#19 PhilCo126

PhilCo126

    Gemini

  • -----
  • Posts: 3239
  • Joined: 14 Jan 2005
  • Loc: coastline of Belgium

Posted 14 May 2011 - 01:00 PM

Budget would be about US $ 7500.00

#20 skybsd

skybsd

    Skylab

  • *****
  • Posts: 4281
  • Joined: 01 Feb 2008

Posted 14 May 2011 - 01:29 PM

Hello,
Good to hear from you again..,

Budget would be about US $ 7500.00


At your required payload, usage and FL (not to mention that you're in the EU), let's be honest here.., that's tight.

As far as brand new is concerned the only option open to you at this time, is the Gemini G42 . On the bright side, this is the same mount pictured with your OTA at APM .

Used.., well, at present there are a few options - at a glance: -

Very Best Option
Next Best Option
In Europe
MI-250
Losmandy GM-150

Hope that helps..,

Regards,

skybsd

#21 PhilCo126

PhilCo126

    Gemini

  • -----
  • Posts: 3239
  • Joined: 14 Jan 2005
  • Loc: coastline of Belgium

Posted 15 May 2011 - 11:04 AM

We'll probably go for a brand new CGE Pro ...

#22 skybsd

skybsd

    Skylab

  • *****
  • Posts: 4281
  • Joined: 01 Feb 2008

Posted 15 May 2011 - 11:20 AM

We'll probably go for a brand new CGE Pro ...


Best wishes - do let us know how you get on, okay?

Regards,

skybsd

#23 frolinmod

frolinmod

    Surveyor 1

  • -----
  • Posts: 1829
  • Joined: 06 Aug 2010
  • Loc: Southern California

Posted 17 May 2011 - 01:28 PM

I spoke to a well known astronomer here in Melbourne
who claims he once made his own mount (30 years ago)
with a washing machine motor to drive it.
He actually got it to track for 5 minute frames
using drift alignment & no guiding

Grandpa said, "Sonny, when I was your age I walked 10 miles through the snow to school."

#24 gdd

gdd

    Apollo

  • -----
  • Posts: 1456
  • Joined: 23 Nov 2005
  • Loc: Lynnwood, WA (N/O Seattle)

Posted 17 May 2011 - 09:04 PM

Grandpa said, "Sonny, when I was your age I walked 10 miles through the snow to school."



"And that was uphill both ways!"

Gale

#25 PhilCo126

PhilCo126

    Gemini

  • -----
  • Posts: 3239
  • Joined: 14 Jan 2005
  • Loc: coastline of Belgium

Posted 18 May 2011 - 11:42 AM

Only a few years after production, some "horror" stories crept up about the mechanical & electrical problems of the CGE Pro... I guess as with all mounts, there're might be some produced on a Monday and others on a Friday :shocked:

Currently we're considering a Losmandy solution...






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics