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Insulation jacket for Mak?

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#251 Rock22

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Posted 22 February 2018 - 11:48 AM

Hi, will w, let me know if you want my help in making your dew shield! And if anyone else has a Skywatcher or Orion 180mm Mak-Cass, I’d be happy to help you with a dew shield or insulation as well! But if there are clear skies... you may have to wait!
 

#252 will w

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Posted 22 February 2018 - 03:53 PM

Hi Rock, My roll of reflectic just got here today.My scope is a lx-90 10 inch.with weight rail under it. Telrad on top.Finder scope bracket too.I have a dewstrip that will be on the front.and a dew sheild too.Its about 12 to 14 inches long. Due to the weight rail i will build the sheild in two parts, got velcro.Will take some pics of it while i am making it. Hope you have clear skies. will w


 

#253 graffias79

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Posted 23 February 2018 - 09:40 AM

Crossing my fingers that next Tuesday holds true for being clear. I am dying to try my new Mak!  I already made the reflectix shield so I'll be ready.


 

#254 Rock22

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Posted 23 February 2018 - 09:58 AM

Crossing my fingers that next Tuesday holds true for being clear. I am dying to try my new Mak! I already made the reflectix shield so I'll be ready.


Hope you have clear skies to enjoy your new and insulated mak! And thanks for starting this thread!
 

#255 graffias79

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Posted 23 February 2018 - 01:35 PM

Thanks!  I saw the insulation thing referenced in another thread and it caught my attention so I thought I'd pursue finding out what it was about!


 

#256 will w

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Posted 23 February 2018 - 11:06 PM

Hi Rock , Got the sheild built. I did just the tube,but i have the back cut out . If i need it i can put it on later.. I had go back and cut out the inside layer so i can put my dew strip on.I got some pictures,but have never posted pictures on c/n. Not sure how to do it . will w


 

#257 TG

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Posted 24 February 2018 - 02:46 PM

Wow, I take a brief break from CN and there's a brawl about how to use Reflectix, 13 pages long and still going on grin.gif

 

At this point, we have people falling into two tribes:

 

1. The Conservatives: people who want to use Reflectix as a means of avoiding turbulence inducing further cooling of the OTA, after cool-down, like it has been understood to work in the past. Many folks on CN follow this ancient religion.

 

2. The Radicals: people who want to prevent the optics from cooling down at all, something the Conservatives consider an exercise in futility. The Radicals think that the Conservatives have been wasting their time waiting for cool-down.  @Yellobeard is the patron saint of this tribe and has already collected several disciples.

 

I'm not sure who has the Truth. I suspect both, in fact, may have parts of the Truth. It may turn out that the Radical Way may work better for scopes of small aperture and not so well for larger ones like the C14, or vice versa. Or it may turn out that the Radical Way gets you 80% of performance immediately but never lets it get to 100%. Or perhaps the Conservative Way may turn out to get you to 100% but only after an inordinately long cooling down period.

 

My wish is for another tribe to rise: the Experimentalists. It may need a patron saint though. Any takers? grin.gif

 

Tanveer.


 

#258 will w

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Posted 24 February 2018 - 03:49 PM

Tanveer, For all the posts for it and aganist it. It all comes down to ONE thing. If it works for you use it. If it dont work for you you dont use it . I have read here.  it works for some and for some it dont work.So that said. You wont know where it will work  for you untill you try it. will w


 

#259 Cpk133

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Posted 24 February 2018 - 04:50 PM

Tanveer, For all the posts for it and aganist it. It all comes down to ONE thing. If it works for you use it. If it dont work for you you dont use it . I have read here.  it works for some and for some it dont work.So that said. You wont know where it will work  for you untill you try it. will w

 

First you need a measurement system that can tell whether or not it works in the first place.  


 

#260 Cpk133

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Posted 24 February 2018 - 05:01 PM

Wow, I take a brief break from CN and there's a brawl about how to use Reflectix, 13 pages long and still going on grin.gif

 

At this point, we have people falling into two tribes:

 

1. The Conservatives: people who want to use Reflectix as a means of avoiding turbulence inducing further cooling of the OTA, after cool-down, like it has been understood to work in the past. Many folks on CN follow this ancient religion.

 

2. The Radicals: people who want to prevent the optics from cooling down at all, something the Conservatives consider an exercise in futility. The Radicals think that the Conservatives have been wasting their time waiting for cool-down.  @Yellobeard is the patron saint of this tribe and has already collected several disciples.

 

I'm not sure who has the Truth. I suspect both, in fact, may have parts of the Truth. It may turn out that the Radical Way may work better for scopes of small aperture and not so well for larger ones like the C14, or vice versa. Or it may turn out that the Radical Way gets you 80% of performance immediately but never lets it get to 100%. Or perhaps the Conservative Way may turn out to get you to 100% but only after an inordinately long cooling down period.

 

My wish is for another tribe to rise: the Experimentalists. It may need a patron saint though. Any takers? grin.gif

 

Tanveer.

Great post.  Right now, I'm in the thought experimentalist camp.  For ultimate performance, my money is with the conservatives.  For grab and go, I'm with the radicals, but I think it comes at the cost of a longer period of "compromised" performance.  When I observe the planets, I throw a towel over the top of my OTA after everything is cooled down, that's my thermodynamic management system.


 

#261 Peter Besenbruch

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Posted 25 February 2018 - 02:31 AM

I was out with my big, silver Maksutov on Friday, showing the sky to students at a school in Hawaii. The temperature plummeted, oh, 2°F in four hours. NO TUBE CURRENTS, but the following conversation:

 

What do you see?

The moon.

Can you see craters?

Maybe...

 

I look and see the faint outline of the moon, dull gray against a duller gray sky. February has been rotten. The times I have managed to get out there with clear skies, and dropping temps, there have been zero cool down issues. In Hawaii, cooling isn't a major issue, but with the Reflectix on the issue doesn't exist. The scope is always ready to go, showing craters... maybe.


 

#262 Jeff B

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Posted 27 February 2018 - 11:33 AM

I just wrapped the session and I'm convinced this has real merit. 

 

The plume I mentioned earlier was more or less gone, only showing itself weakly from time to time at high power.  I could detect no other thermal distortions.  With the seeing really pretty good, I managed to pick out the "Pup" of Sirius at around ~150X (but could not bag it at 270X..I used the magnification that showed the E&F trap stars the easiest and sure enough, could then catch the Pup) .  I've never done this with a Cat before.  The corrector remained fog free the whole viewing session and when I brought the scope in, no dew formed at all on the wrapping.

 

So I got a few things out of this session:

 

1. I do believe this approach works and works well

2. It's straight forward to install

3. No real weight penalty

4. The TEC 7 is a wicked awesome scope with some amazing optics

5. The old AP 400 mount is a great, easy to use workhorse.

 

I next going to wrap the C11!  

 

Jeff

And I did (see post # 219-221) and I had another night of very good seeing and clear skies.  Targets were the Moon, Rigel, M42, and a couple of brighter stars to do star testing (including Sirius).  I also uncovered my TEC 200ED to act as a reference for my C11 observations.  I used a Baader T2 prism and one of my Denk II's (no OCS or switch) with a quick change adapter to keep the back focus as short as possible.

 

So, I got basically the same story as for the 7" TEC Mak earlier except the initial small plume was not as pronounced as in the TEC7.  I have a feeling the plumes are exiting the ends of the baffle tubes if I had to guess.  I was really quite pleased as I could use the C11 immediately at high-ish magnifications and stellar images were sharp as opposed to the standard fuzz balls for the first hour with the C11 even with the active cooling system (which was shut off and sealed over for this test).  

 

Star testing showed the C11 in very good collimation (which, very much unlike my C14, did not change with altitude).   

 

Rigel was just beautiful with the lack of stellar fuzziness really enhancing the view of the double.  M42, and especially the Trap, were nicely framed at ~110X with the E&F stars immediately obvious.  The Trap was "tight" in appearance.  

 

The moon was nice and sharp in the C11, with excellent rendition of detail though, as with most of the SCT's I've owned, a bit fussy on focus though noticeably less than "normal".   I could actually tell when the plume would show up from time to time as detail would reduce slightly and the image, though focused, seemed to shift slightly.   This was different than bouts of unsteady seeing which tended to fuzz over everything. 

 

I found it very instructive to make comparisons with the TEC 200ED as well on the moon.  Through the TEC, there was no "shifty" quality at all to the image and sharp focus was easier to achieve than with the C11.  But the big TEC demonstrated again why I find solar system images though a big refractor, especially a big APO, so arresting.  Yeah, the C11 had a more neutral color "temperature" (with the TEC seeming slightly "warm" in comparison) and the image was brighter and detailed, but there is that something there with the TEC that is just so believable, making the image in the C11, while very good indeed, seem slightly "processed".  

 

But back to the main point, which is, again, I believe there is some real merit to this insulation thing.  It has demonstrated it can mitigate thermal effects in two very different Cats and make them basically immediately usable at higher powers and things only improve after that.  For example, the seeing allowed me to obviously pick up the "Pup" of Sirius with the C11.  That's something I can routinely do with the TEC 200ED, seeing permitting, but I've never been able to do that with the C11, regardless of seeing.  The insulation just really calms everything down in the C11, greatly improving its performance envelope..

 

Also, a very important note here, during the 4 hour session, at no time did the corrector dew up.  To me that's a HUGE advantage by itself as I've ALWAYS had to fight with dew on the C11 and C14, even with the dew shield.  There is no need to run a dew heater now.

 

So, my experience now with two very different Cats is this stuff is a viable alternative to forced air active cooling.  It keeps the tube sealed, thus keeping garbage, including humidity, out that even the best filters will let pass and extends the dew free envelope of the scopes out considerably without having to resort to heaters (I've not reached a corrector dewing situation yet but I'm sure spring will be the real challenge).  

 

Now I'm going to wrap the stuff around my old AP 178 F9 Blue Tube to see if it helps kill off the tube currents which can affect that scope.

 

Jeff 


 

#263 Ron359

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Posted 27 February 2018 - 11:52 AM

 

I just wrapped the session and I'm convinced this has real merit. 

 

The plume I mentioned earlier was more or less gone, only showing itself weakly from time to time at high power.  I could detect no other thermal distortions.  With the seeing really pretty good, I managed to pick out the "Pup" of Sirius at around ~150X (but could not bag it at 270X..I used the magnification that showed the E&F trap stars the easiest and sure enough, could then catch the Pup) .  I've never done this with a Cat before.  The corrector remained fog free the whole viewing session and when I brought the scope in, no dew formed at all on the wrapping.

 

So I got a few things out of this session:

 

1. I do believe this approach works and works well

2. It's straight forward to install

3. No real weight penalty

4. The TEC 7 is a wicked awesome scope with some amazing optics

5. The old AP 400 mount is a great, easy to use workhorse.

 

I next going to wrap the C11!  

 

Jeff

And I did (see post # 219-221) and I had another night of very good seeing and clear skies.  Targets were the Moon, Rigel, M42, and a couple of brighter stars to do star testing (including Sirius).  I also uncovered my TEC 200ED to act as a reference for my C11 observations.  I used a Baader T2 prism and one of my Denk II's (no OCS or switch) with a quick change adapter to keep the back focus as short as possible.

 

So, I got basically the same story as for the 7" TEC Mak earlier except the initial small plume was not as pronounced as in the TEC7.  I have a feeling the plumes are exiting the ends of the baffle tubes if I had to guess.  I was really quite pleased as I could use the C11 immediately at high-ish magnifications and stellar images were sharp as opposed to the standard fuzz balls for the first hour with the C11 even with the active cooling system (which was shut off and sealed over for this test).  

 

Star testing showed the C11 in very good collimation (which, very much unlike my C14, did not change with altitude).   

 

Rigel was just beautiful with the lack of stellar fuzziness really enhancing the view of the double.  M42, and especially the Trap, were nicely framed at ~110X with the E&F stars immediately obvious.  The Trap was "tight" in appearance.  

 

The moon was nice and sharp in the C11, with excellent rendition of detail though, as with most of the SCT's I've owned, a bit fussy on focus though noticeably less than "normal".   I could actually tell when the plume would show up from time to time as detail would reduce slightly and the image, though focused, seemed to shift slightly.   This was different than bouts of unsteady seeing which tended to fuzz over everything. 

 

I found it very instructive to make comparisons with the TEC 200ED as well on the moon.  Through the TEC, there was no "shifty" quality at all to the image and sharp focus was easier to achieve than with the C11.  But the big TEC demonstrated again why I find solar system images though a big refractor, especially a big APO, so arresting.  Yeah, the C11 had a more neutral color "temperature" (with the TEC seeming slightly "warm" in comparison) and the image was brighter and detailed, but there is that something there with the TEC that is just so believable, making the image in the C11, while very good indeed, seem slightly "processed".  

 

But back to the main point, which is, again, I believe there is some real merit to this insulation thing.  It has demonstrated it can mitigate thermal effects in two very different Cats and make them basically immediately usable at higher powers and things only improve after that.  For example, the seeing allowed me to obviously pick up the "Pup" of Sirius with the C11.  That's something I can routinely do with the TEC 200ED, seeing permitting, but I've never been able to do that with the C11, regardless of seeing.  The insulation just really calms everything down in the C11, greatly improving its performance envelope..

 

Also, a very important note here, during the 4 hour session, at no time did the corrector dew up.  To me that's a HUGE advantage by itself as I've ALWAYS had to fight with dew on the C11 and C14, even with the dew shield.  There is no need to run a dew heater now.

 

So, my experience now with two very different Cats is this stuff is a viable alternative to forced air active cooling.  It keeps the tube sealed, thus keeping garbage, including humidity, out that even the best filters will let pass and extends the dew free envelope of the scopes out considerably without having to resort to heaters (I've not reached a corrector dewing situation yet but I'm sure spring will be the real challenge).  

 

Now I'm going to wrap the stuff around my old AP 178 F9 Blue Tube to see if it helps kill off the tube currents which can affect that scope.

 

Jeff 

 

 

A few bits of important data would help; what were the temp & humidity differentials of the scopes initially and at the end of the session, were the scopes inside and then taken outside or all outside at the start for some period, what was the seeing on the seeing scale?


 

#264 Jeff B

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Posted 27 February 2018 - 12:57 PM

"A few bits of important data would help; what were the temp & humidity differentials of the scopes initially and at the end of the session, were the scopes inside and then taken outside or all outside at the start for some period, what was the seeing on the seeing scale?"

 

Good points.

 

OAT at scope set up was 53 degrees F, inside temp was 68 degrees F.  OAT at the start of the observing session one hour later was 49 degrees F, about 40 +/- degrees at the end.   Relative humidity was ~35% at the start and ~45-50% at the end.  The delta between the OAT and that of the dew point was ~ 5 degrees towards the end as best I can tell.

 

Both scopes were always pointed skywards (I didn't use the usual trick of pointing the C11 at the house when I would go inside to warm up for a while).

 

Jeff  


Edited by Jeff B, 27 February 2018 - 01:01 PM.

 

#265 Peter Besenbruch

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Posted 27 February 2018 - 04:45 PM

 

I next going to wrap the C11! 

... It has demonstrated it can mitigate thermal effects in two very different Cats and make them basically immediately usable at higher powers and things only improve after that.  For example, the seeing allowed me to obviously pick up the "Pup" of Sirius with the C11.  That's something I can routinely do with the TEC 200ED, seeing permitting, but I've never been able to do that with the C11, regardless of seeing.  The insulation just really calms everything down in the C11, greatly improving its performance envelope..

That speaks volumes. Seeing the Pup requires steady seeing, and a "steady" scope.


 

#266 graffias79

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Posted 28 February 2018 - 01:20 PM

Well I was finally able to get my first light on the Mak!  Typicaly, the seeing was not the best as the stars were a bit twinkly but I was able to have a look.  Now I admit I've never used a Maksutov scope but I took it out of a 70°F house into a 38°F front yard.  The scope was wearing a dew shield and a reflectix jacket.  I was immediately able to see good features on the moon, and the seeing didn't look any worse than when I use any of my Newtonian reflectors (I have a 4.5", 5", and 10").  I would say under the circumstances that sounds like a win!

 

Since Procyon was near the moon I decided to see what kind of images I would get by defocusing it a little with a high power eyepiece.  I am happy to report that both inside and outside of focus looked very similar with very sharp, even, and clearly defined diffraction rings.  By eye, the collimation seems to be spot on as the central obstruction was centered well and the diffraction rings were the same thickness and spaced evenly.

 

I think this one is a winner!  I'm so happy about that!


 

#267 yellobeard

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Posted 02 March 2018 - 10:29 PM

Ok.. Well, I think I was clear enough about the fact that you need to insulate your scope in a proper(!) way, to enjoy its full benefits! If you don't, then you obviously end up thinking that it doesn't (fully) work!

Furthermore: You should not ever compare 'open' systems like Newtonians, to what we (or I) are talking about here: CLOSED optical systems do hugely benefit from proper insulation, optically 'open' systems do not!!
And: For many reasons, but especially image quality, closed systems do NOT benefit from fans taking outside air in!
Try to do that in a +60% humidity environment and see what happens inside when taking your scope home!

I'm not going deeper into the 'where is the scientiffic proof?" question, simply because I visually determined that it works great! Thats enough for me, and for a lot of others who actually did their best to do it right.
Indeed: Those who see the benefits should use it, those who don't, should not use it! Simple..

But please don't try to convince 'believers' when you yourself apparently don't 'see' the total picture! Just let them enjoy their huge immediate image improvements, and read their mostly short posts: indeed way more +s than -s !!

One week ago, I had my, of course very properly insulated 16" flex-SCT outside during the 'National Stargazing Day's', and there are two groups of people that are objective and honest, children and drunk people! There were a lot of scopes out there, up to a very high quality 20" dobsonian and an Astrophysycs APO refractor, and there were a lot of children (and fortunately no drunk people!).. Then it's very satisfying to hear children shout things like "No, you need to go to that big black scope there!! That one is giving the greatest views!"
And it did great! In freeeezzzinggg temperatures, those very crisp and dynamic images of the moon warmed up everybody, including me, showing the full benefits of proper insulation, combined with only 17% (diameter) of obstruction.

So, I'm not going to throw myself into discussions again! No, I'm going to continue enjoying views through that 16" SCT, and work on my 24", very insulated super SCT...
 

#268 graffias79

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Posted 05 March 2018 - 10:51 AM

...
Furthermore: You should not ever compare 'open' systems like Newtonians, to what we (or I) are talking about here: CLOSED optical systems do hugely benefit from proper insulation, optically 'open' systems do not!!
And: For many reasons, but especially image quality, closed systems do NOT benefit from fans taking outside air in!
Try to do that in a +60% humidity environment and see what happens inside when taking your scope home!
...

Just to be clear, I was using my 5" reflector only as a baseline for comparison since I have never owned a Cassegrain telescope before.  My first time out with it I was using the reflectix insulation!


 

#269 GilATM

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Posted 08 March 2018 - 10:55 PM

......

Back in 1992, I solved this by designing a watercooling system at the back of the primary of my 8" newt, and deliberately not insulate the scope's tube. Its huge success made me complete a very similar setup, involving a 12,5" newt..

I've wondered about trying this (I have a full thickness 12.5 mirror which is VERY slow to cool).   Can you describe how you cooled your newtonian?  (Perhaps on a new thread?)

 

Thanks,

Gil

 

BTW, I recall reading that Clyde Tombaugh insulated the insides of his newtonian with cork.


 

#270 Jaimo!

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Posted 09 March 2018 - 09:43 PM

And that's how we get a thread locked...  

 

lock.gif


 


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