Bringing scope in from cold
- starfield
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Bringing scope in from cold
I'm a new refractor owner and had a question about dew. When I bring my refractor inside, I typically leave the cover off to let things dry out. This got me thinking, should I remove the field flattener and let it dry out separately? Or just leave the whole imaging train intact until the scope has had a chance to adjust to room temp?
Thanks
---Steve
Camera: 294 MC Pro, 224 mc, 2600mm
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- notFritzArgelander
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Re: Bringing scope in from cold
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Re: Bringing scope in from cold
Scopes: Apertura AD12 f/5; Celestron C6-R f/8; ES AR127 f/6.4; Stellarvue SV102T f/7; iOptron MC90 f/13.3; Orion ST80A f/5; ES ED80 f/6; Celestron Premium 80 f/11.4; Celestron C80 f/11.4; Unitron Model 142 f/16; Meade NG60 f/10
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Re: Bringing scope in from cold
DSO AP: Orion 200mm f/4 Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,Oiii,LRGB filters; KWIQ/QHY5 guide scope; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on HEQ5 pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome; iOptron CEM60 (pier); Helena Observatory (H2O) Astrobin
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Re: Bringing scope in from cold
I remember you recommending this Kathy, back on the 'other' forum I've been following this advice for four years now and my objectives are clean and spot-free.KathyNS wrote: ↑Sat Sep 14, 2019 7:38 pm When bringing a scope in from the cold, install all covers outside in the cold. Leave the covers on indoors until the next morning. This will prevent the humid indoor air from contacting the cold glass and making the dew worse. Next morning, remove the covers for a few hours to led the original moisture evaporate.
Having done this more than a few times at temps from zero to -40C, I can vouch for and highly recommend Kathy's method
All the best,
"The Hankmeister" Celestron 8SE, orange tube Vixen made C80, CG4, AZ-EQ5 and SolarQuest mounts.
Too much Towa glass/mirrors.
Solar:
H/A - PST stage 2 mod with a Baader 90mm ERF on a Celestron XLT 102 (thanks Mike!)
Ca-K - W/O 61mm, Antares 1.6 barlow, Baader 3.8 OD and Ca-K filters with a ZWO ASI174mm.
W/L - C80-HD with Baader 5.0 & 3.8 Solar film, Solar Continuum 7.5nm and UV/IR filters with a Canon EOS 550D.
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Re: Bringing scope in from cold
I would always recommend not bringing a cold scope regardless. We had a local do this with a large refractor. He was having issues focusing and finally took at look at it and found the lens cracked.
Dan
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Re: Bringing scope in from cold
Wow... -40C.... As someone who observes from San Diego that's an entirely different level of cold!Thefatkitty wrote: ↑Sat Sep 14, 2019 8:35 pmI remember you recommending this Kathy, back on the 'other' forum I've been following this advice for four years now and my objectives are clean and spot-free.KathyNS wrote: ↑Sat Sep 14, 2019 7:38 pm When bringing a scope in from the cold, install all covers outside in the cold. Leave the covers on indoors until the next morning. This will prevent the humid indoor air from contacting the cold glass and making the dew worse. Next morning, remove the covers for a few hours to led the original moisture evaporate.
Having done this more than a few times at temps from zero to -40C, I can vouch for and highly recommend Kathy's method
All the best,
Camera: 294 MC Pro, 224 mc, 2600mm
Guiding: ZWO 290 mini on 120mm guide scope
Mounts: EQ6R-Pro, EQ Platform.
Filters: Optolong L-Pro & L-Enhance, Chroma 36mm LRGB, 5nm HA, 3nm OIII, 3nm SII.
Software: SharpCap, SGP, StarTools 1.7, Photoshop, Pixinsight
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Re: Bringing scope in from cold
I'll happily trade with you any day... My
Well, still a few months to go until that
Enjoy your warmth and all the best,
"The Hankmeister" Celestron 8SE, orange tube Vixen made C80, CG4, AZ-EQ5 and SolarQuest mounts.
Too much Towa glass/mirrors.
Solar:
H/A - PST stage 2 mod with a Baader 90mm ERF on a Celestron XLT 102 (thanks Mike!)
Ca-K - W/O 61mm, Antares 1.6 barlow, Baader 3.8 OD and Ca-K filters with a ZWO ASI174mm.
W/L - C80-HD with Baader 5.0 & 3.8 Solar film, Solar Continuum 7.5nm and UV/IR filters with a Canon EOS 550D.
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- Lady Fraktor
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Re: Bringing scope in from cold
All caps on first of course
See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885
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Re: Bringing scope in from cold
My practice of keeping caps off is aimed at minimizing thermal relaxation time, getting the optics up to temperature and dry as quickly as possible. The corrector plate of my MK66 is over 16 years in service this way and looks quite good. So for my conditions (high indoor humidity) It's not clear that I'm mistreating my optics by leaving caps off. (I put them back on as soon as dew is gone indoors.)
Could it be that the "caps on first" approach works because the indoor humidity is low? No worries about entrained moisture?
I didn't pay much attention to the order of doing things until an acquaintance near Seattle (who put caps on first) found a spider web of mildew developing between the front elements of a TV Genesis. So that's what got me started on the dry first then cap routine. His house also had musical instruments and was quite well humidified. (Also, there's the Seattle issue where objective lenses have optional windshield wipers.)
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Re: Bringing scope in from cold
Keeping the caps on reduces the contact between the moist indoor air and the cold glass, limiting dew to what already formed outdoors. Once the glass has reached thermal equilibrium with the indoor air, it is safe to remove the covers and let the outdoor moisture evaporate. Don't skip the covers-off part after reaching equilibrium, or moisture will become a problem.
DSO AP: Orion 200mm f/4 Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,Oiii,LRGB filters; KWIQ/QHY5 guide scope; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on HEQ5 pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome; iOptron CEM60 (pier); Helena Observatory (H2O) Astrobin
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Re: Bringing scope in from cold
The correct metric to optimize is minimization of the total mass of dew that is accumulated during and after a session. What one wants to avoid is deposits of impurities on optical surfaces Whether the relative humidity inside is high or low might matter, the dew point might matter, temperature might matter. This is a more complicated optimization problem than I appreciated, now that I think of it carefully.
I think we can agree that "don't put it away wet" is a good idea. When I was a student 50 years with a large Clark refractor I didn't have to think. I just did as I was told and replaced the cap on the lens only when it was dry and that's what I've been doing. That was an observatory situation so temperature changes were always modest. Carrying kit between radically different temperature - humidity environments is complicated. I'm skeptical that one solution fits all occasions.
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Re: Bringing scope in from cold
Man... That's some icky-tasting stuff!
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Re: Bringing scope in from cold
http://stc.fs.cvut.cz/pdf16/6535.pdf
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Re: Bringing scope in from cold
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Re: Bringing scope in from cold
Fair enough. But whether you are caps on or caps off when you bring optics in, the
I'm going to stick with my bring indoors caps off approach. That TV Genesis I saw in Seattle really put the fear of moisture in me. So although I set up "caps on" I bring the caps indoors immediately so they stay warmer.
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Re: Bringing scope in from cold
My preference of capping and storing before bringing inside could just be years of habit.
The temperature inside is controlled as well, 40%-50% humidity and 20°C due to multiple wooden instruments as well.
One thing I have not seen anyone mention is desiccant, I have tea balls filled that go inside the focuser drawtube when the telescope is capped.
Another thing that may hinder fungus growth is the amount of solar viewing with the Herschel wedge, all of my telescopes get bathed in UV at some point so it may help a bit.
i have never (so far) had a issue with mold/ fungus on the lens or inside the tubes.
See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, SXP2, AXJ, AXD
Az/Alt: AYO Digi II, Stellarvue M2C, Argo Navis encoders on both
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Re: Bringing scope in from cold
You make a good case for solar viewing.
The TV Genesis with the mildew was thankfully not mine. I had been hired to do calculus / physics tutoring and the student became aware that I did my own maintenance work on refractors. After one session I was shown the scope and was asked if I would fix the problem. I declined to clean and collimate anything more complex than a doublet, recommending it be sent back to Al Nagler. I won't collimate a Petzval. So I haven't a clue what the rear doublet was like.
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Re: Bringing scope in from cold
It is the really good grade, lightly used and typically they just throw it away since it cannot be reused.
Every couple of months I go to the local shop and get a box full of desiccant cylinders for me and my viewing friends.
See Far Sticks: Elita 103/1575, AOM FLT 105/1000, Bresser 127/1200 BV, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS 100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, SXP2, AXJ, AXD
Az/Alt: AYO Digi II, Stellarvue M2C, Argo Navis encoders on both
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Tak prism, TAL, Vixen
Eyepieces: Antares to Zeiss (1000101)
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Re: Bringing scope in from cold
Apparently I have been doing it all wrong, the past half a century. I bring in the telescope and wait for the lenses being dry, before capping.Takes 40 minutes or so. Luckely none of my telescopes has been complaining
GrabnGo on Alt/AZ : *SW Startravel 102 F/5 refractor( widefield, Sun, push-to), *OMC140 Maksutov F/14.3 ( planets).
Most used Eyepieces: *Panoptic 24, *Morpheus 14, *Leica ASPH zoom, *Zeiss barlow, *Pentax XO5.
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Rijswijk Public Observatory: * Astro-Physics Starfire 130 f/8, * 6 inch Newton, * C9.25, * Meade 14 inch LX600 ACF, *Lunt.
Amateur astronomer since 1970.
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