Glassthrower
Vendor - Galactic Stone & Ironworks
Reged: 04/07/05
Posts: 17931
Loc: Oort Cloud 9
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As a relatively-new owner of a Mak (Orion 150mm MCT), I am embarassingly ignorant of some basic principles of "cool down". Almost all of my previous experience is with small refractors, which have very little or no cool down issues.
I have a couple of basic questions that I am unclear about. And I was surprised that Google reveals very little about the Matsukov design or it's use. (try Googling the Meade LX series or the Celestron C8 by contrast and see the results) In fact, I could not find a single "fan site" or personal site anywhere on the web that is dedicated to the Matsukov design. All I could find was manufacturer and vendor sites, or occasional forum discussion threads. Well at any rate, to the point :
1) When I have my MCT outside cooling down prior to observing, should I leave the eyepiece hole open to the outside air to facilitate quicker cooling? I'm not too worried about dust and the like this time of year, and I am thinking I could put a small piece of screen over the hole to keep out any insects. Would this help the mirror inside to reach equilibrium faster?
2) If I took a small, portable-type (or handheld), battery-operated fan and rigged up something to point it at the eyepiece hole, would this help it cool down quicker? Would the resulting weak stream of moving outside air make much of a difference inside the tube? Or would I just be blowing dust and contaminants into the OTA?
3) What would be a typical expected cool-down time to go outside from a house that is 20-30 degrees warmer than the outside air?
I still don't have my mount back yet, so I have too much time to sit here and ponder these things. 
Thanks in advance for any help and clear skies!
MikeG
PS - are there any good sites out there dedicated to the Mak design that are not trying to sell them?
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Michael Gilmer - Member of the Meteoritical Society & Collector of Falling Stars.
☄ ⒼⒶⓁⒶⒸⓉⒾⒸ ⓈⓉⓄⓃⒺ ☞ www.galactic-stone.com
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Larry F
Carpal Tunnel
Reged: 05/24/04
Posts: 2096
Loc: Westchester, NY
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I wonder why Lymax doesn't make coolers for the Chinese 127 and 150 Maks that are sold under Orion and other names.
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More stuff than I need
Not as much as I want
(Main scope: CPC800/Mallincam Color Hyper Plus)
Mason & Hamlin BB 2140 mm (grand piano)
Westchester Amateur Astronomers
My Gallery
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scope dog
Pooh-Bah
Reged: 07/26/04
Posts: 1490
Loc: USA
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Mike,
After years of playing games. Active coolers that blow air in, brings in other guest too. Keeping the scope outside hours before gets interesting too, weather may move in. I found having an outside secure building is best, garage, shed . This way you are always ready to go, tear down is faster too. I like keeping my scopes in their cases even if I had an observatory. There I can buffer the temp changes and control the environment with a drier.
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Jim
Santel MK91
Astreya-SAPO
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Larry Geary
Carpal Tunnel
Reged: 09/24/06
Posts: 1585
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Mike,
1) Yes, it would help a bit. YMMV, but I've never had a bug get into my Maks, and I don't cover the eyepiece holes.
2) It doesn't sound like it would do much good. Better would be to search threads here for info on making your own Lymax type cat cooler.
3) That depends. My 6" Mak can take three hours to cool down by that amount, but it's a 1970's design and newer ones like yours may be better. Best thing is to take it outside and see. You can defocus the image of a star and see a bright plume coming from the central obstruction if it hasn't yet reached thermal equilibrium.
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When the past no longer illuminates the future, the spirit walks in darkness. -- Alexis de Tocqueville
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Mert
Post Laureate
Reged: 08/31/05
Posts: 3552
Loc: Spain, Pamplona
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I agree with all the earlier comments,
only wanted to show the "plume" when still
cooling down.
Regards,
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Mert
42º49"N 1º38"W
3" Polarex refractor
6" F12 SW Maksutov,CS2-S "Stepperized"
EQ6 + EQMOD 
SPC900NC/DFK21AU04.AS
My web-page don't laugh, I should make it better! 
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Tuugii
professor emeritus
Reged: 03/22/07
Posts: 533
Loc: Ulaanbaatar, Mongolia
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1) it would help, but I won't do it to my 5" f/10 RuMak Cass. Perhaps it will depend on where are you putting the scope. Like for my case, there is not much dust, but I have a big pool just next to it, so I prefer not to open any holes.
2) if there is not stream directing outside, then it won't be much useful, but just blowing some dust into the tube. I think blowing air by using partial openings will help.
3) for 20-30degree I usually put the scope outside for 30min. Then I check in every 10min.
Tuugii
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telescope=time machine...
Edited by Tuugii (12/22/07 06:02 PM)
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wklemme
super member
Reged: 03/17/05
Posts: 129
Loc: Marin County, CA
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Lacking a built in fan or Lymax style cooler, a working method is to take out the scope as soon as possible. Tilt the scope so that the visual back is elevated. Remove the eyepiece or cover. Place a porous cloth over the opening to minimize insects and dust. Be patient.
Bill
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Various scopes. Still looking.
Burr Hole Vista Observatory
Edited by wklemme (12/23/07 12:38 PM)
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amys
Carpal Tunnel
Reged: 06/12/06
Posts: 2571
Loc: Groton, CT
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Astromart has a Mak-specific forum.
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Amy
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gatorengineer
Carpal Tunnel
Reged: 02/28/05
Posts: 2004
Loc: Hellertown, PA
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I found my 6" pretty much usable out the door with a 20F delta....... Cooldown is certainly less than an hour... My STF does take about that to get settled down, on a 20 degree ish delta.
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A 60mm department store refractor started it all....
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cuir
Carpal Tunnel
Reged: 03/03/07
Posts: 1708
Loc: Up north.
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- I never leave it open ended.
- I Always put on my diagonal and finder eyepiece ASAP for cool-down.
- After that, I put on my counter weight in it's approximate "balanced" posisiton, and I execute my polar alignment of the GEM.
- Then, I proceed to install and align my finder, and them balance my instrument on the mount.
- Setup of the rest of usefull gear; Table chair binocs and charts, layout of the eyepieces etcetera...
By this time the scope is ready for 150X viewing. Add another ½ hour, and seeing will be the only remaining factor affecting your views on all but the most agressive magnifications. Perceived advantages of proceeding in the order I mentioned:
- Less condensation inside the tube. What has to condense does, but no additional humidity seeps in to replace the condensed one (Wick effect).
- Optics being assembled, will cool down as one unit, the optics set will have a more uniform temperature, thus avoiding tube currents caused by temperature diffences.
- Standardizes your setup routine, wich has the advantage of becoming second nature, more efficient and better organized.
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Seb
C8-XLT, 10" Newt, EQ-6.
7mm~16mm Naglers, 24 Pan, TV Plössls, BGOs.
Avg sky: Dark, Transparent w Avg seeing.
Avg drive: 4 hours.
Avg scope time: 6 hours.
Pref'ed observing spots: #1, #2, #3.
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