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

Post pictures of your planetary imaging rig(s) here.

  • Please log in to reply
86 replies to this topic

#26 Jan_Fremerey

Jan_Fremerey

    Mariner 2

  • -----
  • In Memoriam
  • Posts: 265
  • Joined: 03 Mar 2010
  • Loc: Bonn, Germany

Posted 25 January 2025 - 06:35 AM

Is the scope of your own design and construction?

Yes, it is, see my drawings.
 


  • Borodog likes this

#27 GKA

GKA

    Viking 1

  • -----
  • Posts: 514
  • Joined: 03 Jan 2019
  • Loc: South of Norway

Posted 25 January 2025 - 09:27 AM

 

So here are some pics I've taken over the past few months of my rig.  The scope is a 16" Orion xx16g GOTO Dobsonian telescope.  I constructed a roll-off building to house the scope on a concrete pad.  I used a computer cart (which remains in my shop when not in use) that has a capture computer on the lower shelf and a finder and controller computer on the top shelf.  The optical train is fairly compact (about 5" overall length) consisting of an ASI676MC, ADC, and a 2x Barlow element with spacers that yield an f/10 focal ratio.

 

Here is the scope in the stored arrangement.  The ends of the building are split into an upper and lower half which are removed manually and leaned against my property fence.

 
 
Here is the entire system in use.
 
 
Another view of the entire system
 
 
My optical train (note:  This is a duplicate set up with the ASI678MC camera installed.)  It's all threaded except for the 2" spacer that slips into the 2" eyepiece holder on the scope.  The 2x barlow cannot be seen in the photo as it is threaded to the scope side of the ADC barrel up inside that 2" spacer.
 
 
I MacGuyvered this $75 focus motor onto the slow-speed spindle of the scope 2-speed Crayford focuser (this is my spare).  It is operated by a 9V bi-directional variable speed hand controller.

 

Great setupwaytogo.gif . I use the same focuser my self for solar , and i bought it so that i can sit in my observatory and control it , aprox.2m distance.

Works great.

https://www.firstlig...cus-motors.html


  • dcaponeii likes this

#28 Space Cowboy

Space Cowboy

    Vanguard

  • -----
  • Posts: 2,314
  • Joined: 30 May 2010
  • Loc: Cheshire, UK

Posted 26 January 2025 - 09:27 AM

SC, nice scope. I have the SW Classic 250p, with an EQ platform, although I rarely image with it (and never planets any more).

For me the 250 Dob is the perfect size for grab & go imaging as it has the same size base as the 200 model so its not too heavy or bulky. I can whip it outside in a few mins on a whim if there is a break in the clouds or one of those 50/50 forecasts which is often the best we can hope for in the UK. I hate a load of faff with a lot of cables and "extras".

 

When the planets were way low over the UK a few years ago I tried DSO imaging with an EQ5 mount (different scope) and the time and frustration of setting everything up only for the clouds to roll in literally drove me crazy, nearly driving me out of the hobby altogether.

 

I hate EQ mounts and mine has stood unused for over 6 years now. I'd rather try making love to an Octopus than work with an EQ. Give me the simple "up & down, left & right" movement of an Alt/Az any day of the week preferably on a Dob mount waytogo.gif


  • Borodog likes this

#29 RedLionNJ

RedLionNJ

    Cosmos

  • *****
  • Moderators
  • Posts: 9,687
  • Joined: 29 Dec 2009
  • Loc: Red Lion, NJ, USA

Posted 26 January 2025 - 03:17 PM

Here's my setup in New Jersey:

 

12-inch LX200 OTA on a Paramount MX+. Various "side scopes" also on it over time, currently using a 60mm f/4 refractor as an electronic finder.

 

When pointed at less than 70 degrees elevation, I also incorporate an eADC into the imaging train. But I try to keep it simple. This shows just the asi678mc in the JMI NGF-S focuser.

 

 

roof-closed.jpg

 

 

lx200-on-paramount.jpg

 

business-end.jpg


  • scottinash, John Boudreau, ETXer and 7 others like this

#30 sfugardi

sfugardi

    Skylab

  • *****
  • Posts: 4,414
  • Joined: 30 Sep 2006
  • Loc: MA

Posted 26 January 2025 - 04:53 PM

Steve,

That's a lot of fans. I would worry about vibration. Not a problem?

I understand the compulsive need to image with absolutely every hunk of glass you have laying around.

Liam,

You should insulate that thing. :O)



#31 sfugardi

sfugardi

    Skylab

  • *****
  • Posts: 4,414
  • Joined: 30 Sep 2006
  • Loc: MA

Posted 26 January 2025 - 04:57 PM

Mike, I agree vibration limits the benefits. I am still trying to optimize the settings but for sure, less is better than more. I think I may try using Metaguide to quantitatively tune them.

Steve
  • Borodog likes this

#32 Borodog

Borodog

    Hubble

  • *****
  • topic starter
  • Posts: 12,928
  • Joined: 26 Oct 2020
  • Loc: St. Augustine, FL

Posted 26 January 2025 - 09:00 PM

Grant,

Wow. What a rig. Beautiful mount. And bravo using a Mak as a finder!
  • RedLionNJ likes this

#33 ETXer

ETXer

    Apollo

  • *****
  • Posts: 1,256
  • Joined: 03 Sep 2009
  • Loc: North Potomac, MD USA

Posted 27 January 2025 - 10:28 AM

Here we go, very basic; one from the 60s (Q 3.5), the other from the 90s (Celestar 8 Deluxe).

 

Cheers, Allan

Attached Thumbnails

  • 315743898_6067210586646097_8871044353045388874_n.jpg
  • 399953651_7271375266229617_6879640025385373954_n.jpg

  • scottinash, R Botero, KpS and 3 others like this

#34 RedLionNJ

RedLionNJ

    Cosmos

  • *****
  • Moderators
  • Posts: 9,687
  • Joined: 29 Dec 2009
  • Loc: Red Lion, NJ, USA

Posted 27 January 2025 - 11:11 AM

Grant,

Wow. What a rig. Beautiful mount. And bravo using a Mak as a finder!

The 5-inch Mak as a finder was a short-lived experiment - too narrow a field to always get a successful plate-solve.  These days I use a 60mm f/4 refractor with an asi174mm - huge field and quite capable of producing nice images by itself - at an image scale which doesn't require guiding.


  • Borodog likes this

#35 Jan_Fremerey

Jan_Fremerey

    Mariner 2

  • -----
  • In Memoriam
  • Posts: 265
  • Joined: 03 Mar 2010
  • Loc: Bonn, Germany

Posted 27 January 2025 - 12:10 PM

Here's my setup in New Jersey:

Very impressive setup, and a real eye catcher indeed, in particular, the equatorial mount looks very trustworthy. How did you get the mirror cell to an adequate stability?



#36 RedLionNJ

RedLionNJ

    Cosmos

  • *****
  • Moderators
  • Posts: 9,687
  • Joined: 29 Dec 2009
  • Loc: Red Lion, NJ, USA

Posted 27 January 2025 - 02:28 PM

Very impressive setup, and a real eye catcher indeed, in particular, the equatorial mount looks very trustworthy. How did you get the mirror cell to an adequate stability?

Thanks, Jan!

 

The pretty red Paramount is totally unnecessary for planetary imaging, but it's useful for minor planet astrometry, as I can swap out my camera for a larger one - and don't need to autoguide for the 30 or 45 seconds necessary to capture data for astrometric purposes.

 

I have two (what we call in the US) "stand fans" which I start blowing on the mirror cell as soon as I open the roof. I'm sure there are many nights the mirror fails to reach equilibrium with the surroundings (we can frequently have temperature drops of 15C between afternoon and night) and that shows in the captured video - heat plumes, distortion, etc. I'm definitely in the wrong part of the country to make this planetary imaging thing easy.  The best times are usually spring and autumn, when the variation in temperature isn't too much.


  • Jan_Fremerey likes this

#37 LiamMcD71

LiamMcD71

    Lift Off

  • -----
  • Posts: 18
  • Joined: 24 Oct 2024

Posted 28 January 2025 - 07:15 AM

Steve,

 

That's a lot of fans. I would worry about vibration. Not a problem? 

 

I understand the compulsive need to image with absolutely every hunk of glass you have laying around. 

 

Liam,

 

You should insulate that thing. :O)

Hi Mike

 

Hope it's OK to post my updated (improved!) rig now.

I read through the couple of very long, very controversial threads on the topic of insulating an SCT scope.

 

My conclusion is that the Physics is sound.  If a scope has been sitting in a room all day, then essentially it will have reached equilibrium with the room acting as a heat bath of sorts.  If is then taken outside (assuming colder outside in this case) then the outer tube with its much larger surface area, will radiate heat away much faster than the central baffles which has a much smaller relative surface area - this will lead to a steep temperature gradient from the baffle to the wall of the tube, which plume in turn will cause thermal turbulence in the tube).

By slowing down the process of heat radiation from the outer tube, the gradient is reduced, and thus also the internal turbulence.

 

I covered my OTA in a hiking/camping mattress I got at an outdoor store, that has a layer (neoprene?) which is then also covered by a thin shiny sheet (to me the rubber insulates the person from the ground, and then the shiny bit keeps body heat in towards the sleeper?).

 

Photo's of the upgrade.

 

Closeup_CN.png

Scope-CN2.png

Works for me, and I can see the difference, highly recommended. Thanks a stack.

 

Clear skies

Liam


  • scottinash, R Botero, RedLionNJ and 2 others like this

#38 Jan_Fremerey

Jan_Fremerey

    Mariner 2

  • -----
  • In Memoriam
  • Posts: 265
  • Joined: 03 Mar 2010
  • Loc: Bonn, Germany

Posted 28 January 2025 - 07:56 AM

the shiny bit keeps body heat in towards the sleeper?

Hi Liam,

 

on telescope tubes the shiny bit blocks thermal radiation exchange with frosty sky. My tubeless scope has its shiny bit right on the prime mirror front surface.

 

Edit: So the mirror always stays close to ambient air temperature and does not suffer from dew or frost.
 


Edited by Jan_Fremerey, 28 January 2025 - 03:26 PM.


#39 Jan_Fremerey

Jan_Fremerey

    Mariner 2

  • -----
  • In Memoriam
  • Posts: 265
  • Joined: 03 Mar 2010
  • Loc: Bonn, Germany

Posted 28 January 2025 - 08:24 AM

1. don't need to autoguide for the 30 or 45 seconds necessary to capture data for astrometric purposes.

2. I'm sure there are many nights the mirror fails to reach equilibrium with the surroundings (we can frequently have temperature drops of 15C between afternoon and night) and that shows in the captured video

Thank you, Grant, for your instructive comments on both, mechanical and thermal stability which, of course, is much a matter of mechanical as well as thermal coupling of the mirror assembly to the mechanical mount respectively ambient air temperature.
 



#40 Borodog

Borodog

    Hubble

  • *****
  • topic starter
  • Posts: 12,928
  • Joined: 26 Oct 2020
  • Loc: St. Augustine, FL

Posted 28 January 2025 - 08:48 AM

Grant,

 

I would recommend you investigate the so-called "hot tube" method. It's nearly identical to what you have, but places a dew strap (or sometimes two) on the OTA beneath the insulation. The goal is to balance the heat lost through the corrector. If you use a single strap, I would place it equidistant between the corrector and primary mirror. If you use two, I would place them just in front of the primary and just behind the corrector cell. You only need a tiny amount of heat, of order 1 Watt (it needn't be exact). 

 

I am currently using this method, but I need to move my single dew strap to the middle of the OTA, which I will try to find the time to do after planet season is over.

 

Also, you don't mention it, but you should definitely be using a dew shield if you aren't. It eliminates most of the remaining heat loss to the sky that is not handled by the insulation. 


  • RedLionNJ likes this

#41 Jan_Fremerey

Jan_Fremerey

    Mariner 2

  • -----
  • In Memoriam
  • Posts: 265
  • Joined: 03 Mar 2010
  • Loc: Bonn, Germany

Posted 28 January 2025 - 08:56 AM

Also, you don't mention it, but you should definitely be using a dew shield if you aren't. It eliminates most of the remaining heat loss to the sky that is not handled by the insulation. 

Even more effective shoud be venting the front window with ambient air.
 



#42 Borodog

Borodog

    Hubble

  • *****
  • topic starter
  • Posts: 12,928
  • Joined: 26 Oct 2020
  • Loc: St. Augustine, FL

Posted 28 January 2025 - 09:15 AM

Even more effective shoud be venting the front window with ambient air.
 

 

 

Well then you may as well eliminate the tube entirely. ;O)


  • Jan_Fremerey likes this

#43 Jan_Fremerey

Jan_Fremerey

    Mariner 2

  • -----
  • In Memoriam
  • Posts: 265
  • Joined: 03 Mar 2010
  • Loc: Bonn, Germany

Posted 28 January 2025 - 11:03 AM

Well then you may as well eliminate the tube entirely. ;O)

waytogo.gif


  • Borodog likes this

#44 RedLionNJ

RedLionNJ

    Cosmos

  • *****
  • Moderators
  • Posts: 9,687
  • Joined: 29 Dec 2009
  • Loc: Red Lion, NJ, USA

Posted 28 January 2025 - 12:51 PM

Grant,

 

I would recommend you investigate the so-called "hot tube" method. It's nearly identical to what you have, but places a dew strap (or sometimes two) on the OTA beneath the insulation. The goal is to balance the heat lost through the corrector. If you use a single strap, I would place it equidistant between the corrector and primary mirror. If you use two, I would place them just in front of the primary and just behind the corrector cell. You only need a tiny amount of heat, of order 1 Watt (it needn't be exact). 

 

I am currently using this method, but I need to move my single dew strap to the middle of the OTA, which I will try to find the time to do after planet season is over.

 

Also, you don't mention it, but you should definitely be using a dew shield if you aren't. It eliminates most of the remaining heat loss to the sky that is not handled by the insulation. 

I really should install my dew straps again, yes :)

 

Dew shield - sometimes I have it on, sometimes I have it off.  During planetary sessions, I tend to have it off more, as I can't reach the collimation screws with it on.


  • Borodog likes this

#45 Borodog

Borodog

    Hubble

  • *****
  • topic starter
  • Posts: 12,928
  • Joined: 26 Oct 2020
  • Loc: St. Augustine, FL

Posted 28 January 2025 - 03:08 PM

I really should install my dew straps again, yes smile.gif

 

Dew shield - sometimes I have it on, sometimes I have it off.  During planetary sessions, I tend to have it off more, as I can't reach the collimation screws with it on.

The thing is though that it massively reduces the view factor from the corrector to the sky. It makes a real difference. I use a plastic & velcro dew shield that is easily removed and then reinstalled after collimation.



#46 Jan_Fremerey

Jan_Fremerey

    Mariner 2

  • -----
  • In Memoriam
  • Posts: 265
  • Joined: 03 Mar 2010
  • Loc: Bonn, Germany

Posted 28 January 2025 - 04:00 PM

I use a plastic & velcro dew shield that is easily removed and then reinstalled after collimation.

Is collimation a frequent action especially with SC telescopes? I never have re-collimated my setup since first light.
 



#47 Borodog

Borodog

    Hubble

  • *****
  • topic starter
  • Posts: 12,928
  • Joined: 26 Oct 2020
  • Loc: St. Augustine, FL

Posted 28 January 2025 - 04:13 PM

Is collimation a frequent action especially with SC telescopes? I never have re-collimated my setup since first light.
 

It is for some people, especially with with larger apertures. The larger the aperture, the tighter the collimation tolerances become, and the heavier the mirror, the harder it is to make the scope stiff enough to preserve collimation after slewing to a different part of the sky. My 11" SCT holds collimation very well and rarely needs adjustment, but it eventually does, just from thermal cycling alone. But once you get up to about a C14 or above, collimation becomes much more frequent. Some people have to re-collimate for every slew, and their scopes will go out of collimation just tracking a few hours from east to west.


  • Jan_Fremerey likes this

#48 Andrea Salati

Andrea Salati

    Apollo

  • *****
  • Posts: 1,072
  • Joined: 24 Nov 2010
  • Loc: Jacksonville, FL

Posted 28 January 2025 - 04:16 PM

I check the collimation of my tiny C5 often and fine tune it very seldom.


  • Jan_Fremerey likes this

#49 Jan_Fremerey

Jan_Fremerey

    Mariner 2

  • -----
  • In Memoriam
  • Posts: 265
  • Joined: 03 Mar 2010
  • Loc: Bonn, Germany

Posted 29 January 2025 - 06:41 AM

Collimation
Mechanical stiffness
Thermal stability
Stray light

 

If the above issues are specific to catadioptric imaging systems, I wonder why no alternative designs are presented here.



#50 Mitchell Duke

Mitchell Duke

    Aurora

  • *****
  • Posts: 4,597
  • Joined: 22 Apr 2008
  • Loc: Classified

Posted 29 January 2025 - 07:48 AM

Collimation
Mechanical stiffness
Thermal stability
Stray light


If the above issues are specific to catadioptric imaging systems, I wonder why no alternative designs are presented here.


These are specific to all imaging systems not just catadioptric.
  • Jan_Fremerey likes this


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