Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Any Intes MC & MN fans?

  • Please log in to reply
205 replies to this topic

#201 stuart keenor

stuart keenor

    Mariner 2

  • -----
  • Posts: 202
  • Joined: 20 Feb 2011

Posted 25 May 2020 - 11:10 AM

Very interesting thread thanks for sharing πŸ‘

#202 luxo II

luxo II

    Surveyor 1

  • -----
  • Posts: 1,995
  • Joined: 13 Jan 2017
  • Loc: Sydney, Australia

Posted 26 May 2020 - 02:50 AM

I want to study a helicoid a bit more 

I'm mildly curious to know what you find - the only examples I've seen are the really small ones for guiders, and the weird tilted crayford helical idea that seems to be a DIY job - and not strong enough to support a camera rigidly.

 

The only other large examples I've seen are DIY ones where the focuser has been cannibalised from a camera lens barrel - which would probably work, as the larger ones are intended to support the weight of the camera body.

 

The opportunity arose recently to acquire an optical set from a 10" Intes f/5.5 MN, in need of recoating and a rebuild... it would make a nice project for someone keen to do a DIY.


Edited by luxo II, 26 May 2020 - 02:58 AM.


#203 Tony Owens

Tony Owens

    Explorer 1

  • -----
  • Posts: 84
  • Joined: 10 Aug 2014
  • Loc: Wicklow, Ireland

Posted 26 May 2020 - 11:17 AM

I'm mildly curious to know what you find - the only examples I've seen are the really small ones for guiders, and the weird tilted crayford helical idea that seems to be a DIY job - and not strong enough to support a camera rigidly.

 

The only other large examples I've seen are DIY ones where the focuser has been cannibalised from a camera lens barrel - which would probably work, as the larger ones are intended to support the weight of the camera body.

 

The opportunity arose recently to acquire an optical set from a 10" Intes f/5.5 MN, in need of recoating and a rebuild... it would make a nice project for someone keen to do a DIY.

The biggest commonly-found helicoid is M65 female to M65 male. Cheap, Chinese-made in fairly large numbers, used by folk who convert pre-digital large format camera and projection lenses to suit DSLR bodies. I'm not convinced about bending stiffness, and motorisation isn't straightforward due to the precession of the control ring while rotating it. Not to mention backlash.

Apart from helicoids, the obvious candidates for a motorised heavy duty low profile focuser are the Clement flexural one, which is very large and rather heavy, and the series of parallel screw-driven designs promoted by FLI (http://www.flicamera...sers/index.html) which are interesting but not interesting enough to tickle my fancy. What would tickle my fancy would be to integrate a parallel-screw focuser with a 5 x 2" filterwheel and an off-axis guider, all-in-one. Cant think why nobody has done that yet.

Re your MN10 optical set, I would certainly be interested in turning that into a instrument once more, either for myself or as a commission for someone else. But not a DIY - it would be done to a professional standard :) 

 

Tony



#204 Tony Owens

Tony Owens

    Explorer 1

  • -----
  • Posts: 84
  • Joined: 10 Aug 2014
  • Loc: Wicklow, Ireland

Posted 30 May 2020 - 07:00 AM

The biggest commonly-found helicoid is M65 female to M65 male. Cheap, Chinese-made in fairly large numbers, used by folk who convert pre-digital large format camera and projection lenses to suit DSLR bodies. I'm not convinced about bending stiffness, and motorisation isn't straightforward due to the precession of the control ring while rotating it. Not to mention backlash.

Apart from helicoids, the obvious candidates for a motorised heavy duty low profile focuser are the Clement flexural one, which is very large and rather heavy, and the series of parallel screw-driven designs promoted by FLI (http://www.flicamera...sers/index.html) which are interesting but not interesting enough to tickle my fancy. What would tickle my fancy would be to integrate a parallel-screw focuser with a 5 x 2" filterwheel and an off-axis guider, all-in-one. Cant think why nobody has done that yet.

Re your MN10 optical set, I would certainly be interested in turning that into a instrument once more, either for myself or as a commission for someone else. But not a DIY - it would be done to a professional standard smile.gif

 

Tony

Further to the discussion about the imaging qualities of M-N designs based on Intes-Micro optical sets, both from them and 'oachbuilders' like Matthias Wirth, it appears that there is no reason why M-N scopes up to 12" aperture should not be used as rugged transportable deep-sky astrographs, in addition to their usual role as high resolution 'planet-killers'. All that is required is an interchangeable diagonal mirror, which is a straightforward piece of opto-mechanical engineering. The limited backfocus issue, and the lack of structural stiffness in most M-N focusers is easily resolved by integrating focuser, filter wheel, camera rotator and off-axis guider into a single stiff module. See below for the basic concept:

 

MN76_focuser-filterwheel-guider_1.jpg

 

 

and in section:

MN76_focuser-filterwheel-guider_2.jpg

 

There is 123mm of backfocus beyond the OTA exterior of an MN-76. Removing the weak and floppy small Newtonian-type focusers normally-used, allows all of this backfocus to be used to accommodate a much stiffer imaging train, suitable for eyepieces and cameras up to full-frame. A door in the tube between the reinforcing rings and a different secondary mount on the corrector allows for convenient exchange of diagonals. For planetary high contrast imaging and visual use, standard low obstruction ones can be used, while a much larger one enables low vignetting while preserving essentially diffraction-limited imagery at F6 across a 34mm diameter image circle.

 

I understand that some owners of Intes-Micro instruments are not particularly interested in imaging, and may be infrequent observers, perhaps some even are mindful of the value of these telescopes as collectibles. The fact remains however, that MN scopes can be very capable astrographs beyond the domain of small APO's and competing with medium-sized RC scopes (including corrected aspheric Cassegrains from Meade and Celestron) while also offering much better high contrast visual performance. That is interesting! 


  • eros312, n2068dd and luxo II like this

#205 luxo II

luxo II

    Surveyor 1

  • -----
  • Posts: 1,995
  • Joined: 13 Jan 2017
  • Loc: Sydney, Australia

Posted 30 May 2020 - 05:53 PM

Tony likewise the Intes MCTs - there are a few examples on Astrobin, and then there’s the Astronominsk website (Santel scopes).

I’ve succumbed too and have ordered a camera to dabble at the planets later this year.

Edited by luxo II, 30 May 2020 - 07:19 PM.


#206 Tony Owens

Tony Owens

    Explorer 1

  • -----
  • Posts: 84
  • Joined: 10 Aug 2014
  • Loc: Wicklow, Ireland

Posted 31 May 2020 - 04:52 PM

Thanks for putting me on to the Astronominsk website.  Some amazingly refined yet elegantly simple technology comes from this part of the world, not to mention a more communitarian approach to doing astro projects. That big Klevsov certainly seems to produce the goods on planetary imaging.




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics