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Insulation jacket for Mak?

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#201 will w

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Posted 13 February 2018 - 02:40 PM

Hi Rock22,  Thanks for the reply. I will get some fabric tape and line the outer edges when i build mine. I have a LX-90 10 SCT with a weight rail and a telrad on it . So i will have to build the sheild in two parts. I do not use scope that much in winter time,but since i have a rolloff now i guess that might change. I guess i will see if making this will make any difference. I have read that some people that have observatorys leave their scope and mount  in it all year long. I am wondering now how will this work in the summer time.?? From what i read here this is mainly for winter time use. I mostly do video  all the time,but from time to time i do use EPs too. will w


 

#202 yellobeard

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Posted 13 February 2018 - 03:50 PM

I'm very pleased to read that you all get so many nice results.
If there are any questions that i missed, please ask, then I will try to answer them as soon as possible.
 

#203 Peter Besenbruch

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Posted 13 February 2018 - 04:03 PM

 

 

(images posted)

Clicking the images gives the message that I don't have permission to view them.

You should be able to click on them now.

Yup, fixed.waytogo.gif


 

#204 spongebob@55

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Posted 13 February 2018 - 05:38 PM

So whats the consensus about dew shields?   Use the ones we have and cover with reflectix material, or just make a dew shield from the reflectix material itself? Assuming its stiff enough.......

Bob


 

#205 Peter Besenbruch

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Posted 13 February 2018 - 07:42 PM

So whats the consensus about dew shields?   Use the ones we have and cover with reflectix material, or just make a dew shield from the reflectix material itself? Assuming its stiff enough.......

It depends:

 

If your dew shield is relatively insulated (i.e. not metal), a layer of Reflectix on top of it would work.

 

If your dew shield makes your scope too front heavy, you might want to use Reflectix (suitably blackened on the inside). Of course, blackening probably defeats the purpose of the Reflectix...


 

#206 Rock22

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Posted 14 February 2018 - 11:43 AM

For me, a dew shield is primarily for blocking out stray light. I’m guessing that if you’re in a dark site, a dew shield isn’t as important for this purpose.

I’m not sure if air inconsistencies are a problem in front of the telescope without a dew shield, though. Maybe someone can chime in on this.

According to what I’ve been reading in this thread, if you use a dew shield, it should be insulated. This makes sense as now there is trapped air in front of the meniscus. I’m just not sure whether any air inconsistencies in the empty space of the dew shield are as problematic as those in the tube.

In the summer here in SoCal, I will try both using and not using a dew shield, but again stray light is my main concern. For now, the dew shield stays on my mak until things warm up here.
 

#207 Peter Besenbruch

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Posted 15 February 2018 - 02:17 AM

For me, a dew shield is primarily for blocking out stray light. I’m guessing that if you’re in a dark site, a dew shield isn’t as important for this purpose.

In this case, a dew shield also slows the cooling to the corrector/meniscus, and helps reduce tube currents.


 

#208 Rock22

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Posted 15 February 2018 - 10:39 AM


For me, a dew shield is primarily for blocking out stray light. I’m guessing that if you’re in a dark site, a dew shield isn’t as important for this purpose.

In this case, a dew shield also slows the cooling to the corrector/meniscus, and helps reduce tube currents.
A dew shield will stay on my Mak then. Thanks for confirming!

Edited by Rock22, 15 February 2018 - 10:40 AM.

 

#209 spongebob@55

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Posted 15 February 2018 - 01:23 PM

I definitely need a 'shield'.   If not for dew, for the pine tree sap, and everything else that falls onto my corrector from the air,  living here in the great state of NJ.  Not to mention the bird poo. (yes, that has  actually happened to me!)


 

#210 dweller25

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Posted 15 February 2018 - 04:28 PM

Another observation of my reflectix covered SCT - it does not dew up outdoors or when I bring it back indoors  shocked.gif shocked.gif waytogo.gif


 

#211 Peter Besenbruch

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Posted 15 February 2018 - 07:55 PM

...Not to mention the bird poo. (yes, that has  actually happened to me!)

I'm sure it doesn't cover that significant an area of your corrector. Feel free to leave it on. ;)


 

#212 Rock22

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Posted 16 February 2018 - 11:53 AM

Had 2 hours of clear sky and low magnification (50mm and 40mm 2 inch eyepieces) had no problems. It was about 15 minutes after having the telescope 20 minutes outside while I set up.

Since low magnification was supposed to be less of a problem, I went to 32mm (2 inch), then 25mm (1.25 inch). I spent the rest of the night at 14mm and looked at M81. First time with the Bode’s galaxy - I had been trying to see it since I first got my Mak.

Well, I’m sold. Insulation seems to have worked for me, though my temperature difference was not drastic. My temperature change from the garage to my patio was about 70F to 55F at midnight. It was a warm day yesterday, so I wasn’t surprised our garage was still warm. The temperature was 50F when I finished.

Now, I need to figure out how to mount my fully insulated (both layers on) Mak more quickly and without worry it will slip. Tonight, I’ll put on the outer tube layer AFTER I mount the telescope (with only one layer of insulation on) and see if the views are just as good.
 

#213 Bean614

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Posted 16 February 2018 - 07:40 PM

", I’ll put on the outer tube layer AFTER I mount the telescope"....??? 

Actually, you'll then not get the correct effect.  If you're going to insulate, I suggest doing all of it while indoors.


 

#214 WadeH237

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Posted 16 February 2018 - 08:48 PM

Actually, you'll then not get the correct effect.  If you're going to insulate, I suggest doing all of it while indoors.

If this is true, that's going to be an issue for larger scopes.  There is no way that I would try to mount my C14 with a layer of insulation that extends beyond the front of the scope.  I need to be able to get a hold of the telescope directly, and not through some cover that could slip.

 

I'm looking forward to hearing from some people who try this.


 

#215 Rock22

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Posted 17 February 2018 - 12:11 PM

", I’ll put on the outer tube layer AFTER I mount the telescope"....???
Actually, you'll then not get the correct effect. If you're going to insulate, I suggest doing all of it while indoors.

I’ll have one layer on when I first bring the telescope out. I hope that will keep the tube from any sudden temp changes. I just need to mount the Mak as well and as quickly as I can and then put on the second layer. That’s the plan. I’ll see how that works.

Edited by Rock22, 17 February 2018 - 12:12 PM.

 

#216 Bean614

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Posted 17 February 2018 - 08:34 PM

"There is no way that I would try to mount my C14 with a layer of insulation that extends beyond the front of the scope."

      Wade, if you look at some of the photos I posted earlier in this thread, of my C6 and C8, you'll see that the insulation on the OTA ended at its front cell.  The insulated Dew Shield had an "extension" of insulation of the same length as the front cell. It slides on and off and meshes perfectly. 


 

#217 WadeH237

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Posted 17 February 2018 - 11:40 PM

Wade, if you look at some of the photos I posted earlier in this thread, of my C6 and C8, you'll see that the insulation on the OTA ended at its front cell.  The insulated Dew Shield had an "extension" of insulation of the same length as the front cell. It slides on and off and meshes perfectly. 

I'm planning a little bit different setup.

 

The dew shield on my C14 (and Astrozap flexible version) is pretty tricky to set up.  It has just a small amount of area that makes contact with the scope, and the velcro needs to be tight enough to provide grip to support the weight of the dew shield, but not so tight that it won't fit onto the scope.

 

To make it a bit more robust, I've picked up a roll of Reflectix that is quite a bit wider than the C14 tube is long.  I plan on cutting a single layer that will wrap the scope and installed dew shield in one piece, and then add a second layer that wraps just the scope.  So the inner layer of insulation will be a single piece that covers both the scope and dew shield, and the second layer will cover just the length of the scope.

 

Also, most of the time that I use my C14, it's in the field at a dark sky site.  When I do that, the scope is covered during the day by a Telegizmos cover.  I plan to remove the cover and install the insulation wrap in the evening when the sun has set low enough that it is not shining directly on the scope.  When I am done observing, I will remove the insulation and re-cover the scope.  In this case, the scope is already acclimated to the outside air temperature when I will be installing the insulation layer.  Its main purpose in that case is to prevent tube currents as the air temperature drops at night.


 

#218 Exnihilo

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Posted 18 February 2018 - 01:38 AM

Having read this thread with much interest, I’ve still decided to get TEMPest fans for my C11 Edge, and in fact just ordered them.  At some point I’m going to fit up a reflectrix covering; it seems like such an easy exercise, why NOT do it? When I go to my dark sky site here in AZ, I can compare the fans with/without reflectrix.  There’s a pretty good temperature gradient there with the altitude and dry typically AZ air.  Thanks everyone for all the information here!


 

#219 Jeff B

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Posted 18 February 2018 - 12:58 PM

Ok, I got the C11 all ugly'd up.  

 

The back & Reflectix end cap.  The fans will be covered.

 

Jeff

Attached Thumbnails

  • Back Side.jpg
  • End Cap.jpg

 

#220 Jeff B

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Posted 18 February 2018 - 12:59 PM

The dew cap.

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  • Dew Cap.jpg

 

#221 Jeff B

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Posted 18 February 2018 - 01:01 PM

And now the complete package.

 

Just need good weather (The newly insulated scope curse is fully active for that). 

 

Jeff

 

Attached Thumbnails

  • On Mount 2.jpg

 

#222 Ron359

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Posted 18 February 2018 - 01:20 PM

Having read this thread with much interest, I’ve still decided to get TEMPest fans for my C11 Edge, and in fact just ordered them.  At some point I’m going to fit up a reflectrix covering; it seems like such an easy exercise, why NOT do it? When I go to my dark sky site here in AZ, I can compare the fans with/without reflectrix.  There’s a pretty good temperature gradient there with the altitude and dry typically AZ air.  Thanks everyone for all the information here!

This has been an interesting thread of one side an age old argument.  Please report your findings.  Insulating may work well enough to help in high humidity environs but I think for those of us in low humidity environs where there are large and continuous drops in night temps, that insulating the tube will only prolong the 'agony' of cool down to equilibrium so the scope will continue to radiate heat all night.  Seems like simple physics and also why  SCT carbon fiber tubes were taken off the market as many reported they took forever to cool down to equilibrium.  I'm betting your fans will be far more effective.   


 

#223 MrJones

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Posted 18 February 2018 - 02:35 PM

I feel like some people are not understanding the main purpose of the insulation. It's the same as Newtonians where the idea came from - to insulate the tube and keep air currents from forming due to differential cooling of the tube. It's not really to cool the scope more slowly to somehow equalize cooling otherwise. The insulation is great for preventing tube currents and you can start observing sooner with it but you still need the whole scope and mirror to equilibrate for best results.

 

This being the case it certainly seems like the best plan is to let the scope equilibrate without insulation and then insulate for observing although it probably doesn't matter too much if you keep the back and front un-insulated.

 

Also, with active cooling (say TEMP-est fans) insulation probably doesn't make much or any difference unless you want to turn the fans off.


 

#224 gfstallin

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Posted 18 February 2018 - 03:18 PM

Ok, I got the C11 all ugly'd up.  

 

The back & Reflectix end cap.  The fans will be covered.

 

Jeff

That is one beautiful-ugly C11! 

 

How many layers of Reflectix did you use? How many rolls including the dew shield? I think I am going to try this with my C9.25. I have TEMP-est fans on my C11 so I might hold off, but it will be interesting to see if it makes a difference for you. 

 

George


 

#225 gfstallin

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Posted 18 February 2018 - 03:48 PM

 

Having read this thread with much interest, I’ve still decided to get TEMPest fans for my C11 Edge, and in fact just ordered them.  At some point I’m going to fit up a reflectrix covering; it seems like such an easy exercise, why NOT do it? When I go to my dark sky site here in AZ, I can compare the fans with/without reflectrix.  There’s a pretty good temperature gradient there with the altitude and dry typically AZ air.  Thanks everyone for all the information here!

This has been an interesting thread of one side an age old argument.  Please report your findings.  Insulating may work well enough to help in high humidity environs but I think for those of us in low humidity environs where there are large and continuous drops in night temps, that insulating the tube will only prolong the 'agony' of cool down to equilibrium so the scope will continue to radiate heat all night.  Seems like simple physics and also why  SCT carbon fiber tubes were taken off the market as many reported they took forever to cool down to equilibrium.  I'm betting your fans will be far more effective.   

 

-I had a carbon fiber C11 for a while and it took forever to cool. In fact, I don't think it ever did in real use. I remember testing collimation indoors down a long hallway (110 feet or so). The temperature differential between my apartment and the hallway was about 2 degrees. I ran the Lymax fan with the C11 in the hallway for an hour and I still could not see a stable airy disk - plumes were still really evident. I had never seen this behavior in the hallway with the C8 and C9.25, but still I thought it must have been due to the aperture increase. Now I have an aluminum tube C11 and a Deep Space Products-installed TEMP-est fan. The difference was immediately noticeable between the CF and aluminum versions of the C11. That CF C11 was just not reaching any kind of equilibrium between internal components and tube temperature. Of course, it turned out my CF C11 also had an extra thick rear plate, according Deep Space Products. He had never seen one that thick on any C11. That could not have helped internal temps at all. The aluminium tube with fans works quite well. 

 

George


 


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