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Brooklyn
scholastic sledgehammer
Reged: 07/24/08
Posts: 870
Loc: Central New Jersey
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Hey guys, so far its been a rather dissapointing summer in terms of weather.
Most of the pats 2-4 months were very cloudy, or rainy, but mostly cloudy. Also, its been extremely humid sometimes.
Regardless of using my scope for nearly 6 hours strait one time in 80%-90% humidity, I have never had any Dew form on any of my optic surfaces so far this summer. Sometimes i would notice a very very thin layer of moisture on the rest of the telescope, but i assume that this very thin layer did nothing to the corrector plate, as none of my DSO objects seemed to lose brightness or contrast.
I use a 2002 Meade LX-90 EMC (SCT), however i do not have any dew heaters or dew shield as it has never been an issue for me before, despite living in one of the most humid areas in the USA.
Looking at possible dew shields or dew heaters on the market, are completely absurd! Paying 70 dollars for a piece of aluminum to place around your scope? or 40 bucks for a thick cardboard cover? come on...this is all ridiculously overpriced.
I don't mind spending 100 dollars on a well made lumicon filter...but spending that same amount on a piece of paper or aluminum is just nuts in my opinion.
My question is what months/time of the year (dates would be appreciated) is your Dew problem the worst living here in the northeast USA? I live in new jersey, but anyone in new york Connecticut Pennsylvania etc. would all experience the same weather conditions.
"So what's the dewpoint? If we cool air without changing its moisture content, eventually we'll reach a temperature at which the air can no longer hold the moisture it contains. Then water will have to condense out of the air, forming dew or fog. The dewpoint is this critical temperature at which condensation occurs."
- from http://www.unc.edu/depts/cmse/nature/dewpoint.html
I heard that if it gets humid in sub freezing temperatures while you are observing outside, you will get FROST on your corrector lens and maybe eyepiece!! ouch!!
From your past experiences, which months/dates of the year are the best for outdoor astronomy, considering the high humidity of our area, and dew point consequence.
I refuse to pay 40-100 dollars for a piece of cardboard or aluminum, so i have decided to make my own Dew shield. I will hold off on building Dew heaters until i am more accustomed with the techniques.
If anyone has some ideas as to which materials are good for making a flexible dew shield, let it be known! 
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Meade 8.25"(209.55mm) LX-90 EMC (SCT)
Albert Einstein =>
“Intellectual growth should commence at birth and cease only at death.”
“If you can't explain it simply, you don't understand it well enough.”
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Dylan Gladstone
scholastic sledgehammer
Reged: 08/05/07
Posts: 955
Loc: Connecticut, USA
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I have a dew shield (basically a piece of stiff plastic with velcro and the Orion logo on it). I rarely experience corrector fog, but I do have problems with the eyepieces fogging up.
If I remember right, it was far more of a problem in the winter despite winter air being drier.
To combat eyepiece fog when it's cold out I just keep the unused eyepieces in my pocket so they stay warm. But that doesn't help the eyepiece in the scope after a few minutes so I resort to backing off the eyepiece and waving the dew off with my hand. (That'll amuse the neighbors!  )
In a perfect world scopes would come with built in dew prevention. A dew heater would be built into the the corrector plate holder. Each eyepiece would have built in dew heaters with two concentric conductor rings around the base of the eyepiece with contacts in the diagonal so the moment you drop the eyepiece in it starts warming up.
Of course no one would buy my wacky scope because they'd have to get all new eyepieces to go with it.
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Orion SkyView Pro 127mm Maksutov
Edited by Dylan Gladstone (08/14/08 03:18 PM)
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Brooklyn
scholastic sledgehammer
Reged: 07/24/08
Posts: 870
Loc: Central New Jersey
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Actually the higher priced meade telescopes have built in dew heaters. Mine doesnt because its a few years old, but the ones produced within the past year or so have it.
Perhaps your vision of standard dew heating on all telescopes isnt too far off. Maybe another 2-3 years?
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Meade 8.25"(209.55mm) LX-90 EMC (SCT)
Albert Einstein =>
“Intellectual growth should commence at birth and cease only at death.”
“If you can't explain it simply, you don't understand it well enough.”
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FoxK
Carpal Tunnel
Reged: 11/07/07
Posts: 1810
Loc: Cape Cod, MA
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So far I haven't had too many problems in the NE in summer. I try to get the scope out early and let it sit an hour so mabey the equalized temps keep it dewless. I DO however get alot of frost forming in the winter tho. I have 2 husky batteries tho so I can swap one out whne charging other, or when I image and need 1 for the laptop. I can hook a splitter up to the laptop one and use a small 12v mini hairdryer like dew remover. I try to let the battery powering my mount alone as drawing too much energy sometimes makes it shut off the mount. If that happens to my Laptop tho, since it has its own battery, it can draw the extra needed power from that.
In sum, I have more probs with moisture in the winter, by a wide margin
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Orion 80mm ED Apo Refractor
8" Classic Dob (used as Newtonian on CG5 mount)
Meade 70-AZ-A 70mm Guider using PHD
LS60TCaK/B600/C
CG-5 Advanced GT Mount
Nikon D40x with T-Adaptors
Philips SPC900NC
Imaging Source DMK 21AU04.AS
Dome=the box my mount came in so I can see my solar images in bright sun lol
- click for cloud prediction for Plymouth, MA. area
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Midnight Dan
professor emeritus
Reged: 01/23/08
Posts: 622
Loc: Brockport, NY
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I live in upstate NY, and I have TERRIBLE dew problems in the summer. Especially this summer with all the rain adding to ground moisture. I've come in after a couple hours of viewing with water literally dripping off my equipment.
I have a dew shield and it helps some. On a good night I can get a couple of hours before the corrector plate dews up. On a bad night, not even a half hour.
I bit the bullet and bought the dew heaters. I got a couple of the Dew-not strips, one for the corrector and one for the eyepiece. I got the DewBuster controller (becuase everyone here recommended it) and a 19Ah power supply.
Expensive? Yes, it all adds up. BUT ... I can now view unfettered for as many hours as I can take it. It works great! Dew in the NE in the summer can be a HUGE problem. Dew heaters will solve it.
Now, if only I could find a Dew-Not strip that would fit around my laptop! 
-Dan
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Scopes: Celestron NexStar 8, Orion EON 72mm ED/APO on Astroview mount (EQ3)
Eyepieces: Celestron 40mm, 25mm, Baader Hyperion 13mm, 8mm, 5mm
Other: Telrad, 2x Barlow, 0.63x Focal Reducer, Dew-not strips, DewBuster controller
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Brooklyn
scholastic sledgehammer
Reged: 07/24/08
Posts: 870
Loc: Central New Jersey
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Hmm interesting.
You use rechargeable batteries?
I use shop rite brand 8x C cell batteries. Its 5-7 bucks for an 8 pack of c cells, which is exactly how many you need. The brand name batteries of the same 8 pack C variety are 9-13 bucks. My lx90 is still using the same 8 pack of shop rite batteries that i put in it like a month ago.
If im not mistaken 1 pack of batteries should last 50-80 hours of operation.
Back to the topic though, i figured that winter is probably the absolute worst time to observe as the dew point is high compared to ambient temperature.
How is fall vs spring? Fall sure has a lot of falling leaves which might scratch your corrector plate if the wind throws them at it. But then again spring has all that pollen flying around which builds up on your telescope just like dust, even worse.
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Meade 8.25"(209.55mm) LX-90 EMC (SCT)
Albert Einstein =>
“Intellectual growth should commence at birth and cease only at death.”
“If you can't explain it simply, you don't understand it well enough.”
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maureenford
scholastic sledgehammer
Reged: 04/27/05
Posts: 756
Loc: New Paltz, NY
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I think the best times to observe in the NE are Sept. and Oct. Historically they are less cloudy. No humidity or frost. No bugs. My two week astronomy vacation is always in the fall - in Maine.
Maureen
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Discovery 12.5" TD on Scopebuggy
with Argo Navis and Feathertouch focuser
27mmPan, 13mm & 8mmEthos, 6mm Radian
Howie Glatter laser and Blug
Coronado PST
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Brooklyn
scholastic sledgehammer
Reged: 07/24/08
Posts: 870
Loc: Central New Jersey
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Hmmm maureen this is an interesting theory...my birthday is october 15th great timing! lol 
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Meade 8.25"(209.55mm) LX-90 EMC (SCT)
Albert Einstein =>
“Intellectual growth should commence at birth and cease only at death.”
“If you can't explain it simply, you don't understand it well enough.”
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David Pavlich
Postmaster
Reged: 05/18/05
Posts: 6566
Loc: Mandeville, LA USA 30.38 X 90....
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If you lived here (SE Louisiana), you'd spend the money on dew heaters. Or you'd have to have an extension cord and a hair dryer. A dew shield alone doesn't cut it in this humidity, especially with an SC.
At any rate, I've seen some dew shields made from foam like they make the big hands you see at the football games. A little duct tape and you're good to go.
David
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A few scopes and mounts.
Proud Member; PAS NOLA,
Life expectancies would go WAY up if green vegetables smelled like bacon...
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Mike D
scholastic sledgehammer
Reged: 08/15/07
Posts: 858
Loc: South GA
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Quote:
At any rate, I've seen some dew shields made from foam like they make the big hands you see at the football games. A little duct tape and you're good to go.
David
Another easy do-it-yourself dewshield is to get the cheapest foam mattress pad from Wally World and wrap that with duct tape around the end of your scope. And don't forget the length should be around 1.5 times the aperture of your scope.
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Vixen SXD
Vixen ED80Sf
Hutech 350D
STI Stiletto
Meade 2080
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Exit-pupil
sage
Reged: 11/13/07
Posts: 206
Loc: Eastern Long Island, NY
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Quote:
I think the best times to observe in the NE are Sept. and Oct. Historically they are less cloudy. No humidity or frost. No bugs. My two week astronomy vacation is always in the fall - in Maine.
Maureen
And then comes November, which I've heard is the cloudiest month of the whole year in the northeast. I too love September and October.
Jono
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Lard Greystoke
sage
Reged: 07/27/08
Posts: 203
Loc: Ohio
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Quote:
Quote:
I think the best times to observe in the NE are Sept. and Oct. Historically they are less cloudy. No humidity or frost. No bugs. My two week astronomy vacation is always in the fall - in Maine.
Maureen
It will vary through the region, but here's a lifetime of experience in Ohio:
September through mid-Oct: best weather of year, typically you have high pressure fronts coming from the NW like trains, dry air, blue skies every few days like clockwork.
Come mid-Oct to early Nov, the clouds drop from infinity to about 40 feet, and stay there. Winter brings enormous low pressure areas for hundreds of miles, snow, blizzards, apocalypse. Of course anytime Nov-spring you can get great weather, but you can't rely on it - could be cloudy for weeks.
In spring, as everyone from the Great Plains on east knows, you get everything.
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Lard Greystoke
10" Odyssey Compact
"With Tantor, the elephant, he made friends. How? Ask me not."
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maureenford
scholastic sledgehammer
Reged: 04/27/05
Posts: 756
Loc: New Paltz, NY
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Quote:
Hmmm maureen this is an interesting theory...my birthday is october 15th great timing! lol
I remembered where I read this! "365 Starry Nights" by Chet Raymo. For the first entry for Oct (page 165) he says, "According to the National Climatic Center, October is the least cloudy month of the year for much of the eastern and southern United States."
Maureen
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Discovery 12.5" TD on Scopebuggy
with Argo Navis and Feathertouch focuser
27mmPan, 13mm & 8mmEthos, 6mm Radian
Howie Glatter laser and Blug
Coronado PST
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Brooklyn
scholastic sledgehammer
Reged: 07/24/08
Posts: 870
Loc: Central New Jersey
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Yea im really looking forward to sept oct. I LOVE that kind of weather, and theres no pollen flying around like in spring. The air just feels cleaner somewhat.
Unfortunately, jupiter is going down down down so planetary viewing for us is going to be limited to the moon or maybe uranus/neptune. Neither of Urn or Nept show up with that much detail on my scope, I just see a faint color same as the pictures. Sometimes there's no color at all, just a bright looking blob.
You can look up planetary view times at:
http://www.astroviewer.com/interactive-night-sky-map.php
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Meade 8.25"(209.55mm) LX-90 EMC (SCT)
Albert Einstein =>
“Intellectual growth should commence at birth and cease only at death.”
“If you can't explain it simply, you don't understand it well enough.”
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Tony Flanders
Carpal Tunnel
Reged: 05/18/06
Posts: 2109
Loc: Cambridge, MA, USA
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Quote:
Regardless of using my scope for nearly 6 hours strait one time in 80%-90% humidity, I have never had any Dew form on any of my optic surfaces so far this summer.
Wow, there must be something very weird about your location.
When I observe here inside the urban heat dome, my scopes sometimes stay dew-free for 2 or 3 hours. But in the country or the outer suburbs, they're typically covered with a thin layer of water after a half hour, and water literally drips off them after 3 hours.
Two things that will suppress dew are wind and haze. Haze inhibits radiative cooling, which is the root cause of dew. It's the crystal-clear, still nights when dew is worst. Perhaps you haven't experienced dew because it's been so hazy all summer.
If your site is heavily obstructed by trees, that will also inhibit dew. Essentially, the trees are acting as a dew shield.
Quote:
Looking at possible dew shields or dew heaters on the market, are completely absurd! Paying 70 dollars for a piece of aluminum to place around your scope? or 40 bucks for a thick cardboard cover?
It's not ridiculous if it means the difference between observing and not observing. But your right, it's quite easy to make an excellent dew shield for much less money than this. I've done that for my 70-mm refractor, which has no built-in dew shield. (Newtonians don't need dew shields; they are dew shields.)
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Tony Flanders
eyeglasses
6x15 and 8x32 monoculars
8x25, 7x35, 10x30 IS, 10x50, and 15x70 binoculars
70mm and 100mm achromatic refractors
4.5", 7", and 12.5" Dobs
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Brooklyn
scholastic sledgehammer
Reged: 07/24/08
Posts: 870
Loc: Central New Jersey
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Well thats something i didnt know, thanks it really does all make sense now.
The trees to my west are about 1-2 acres from my observing point. The wind comes through from the west and hits the telescope while traveling east, this is probably the main factor along with the trees.
All this dew protection comes with a heavy price, not being able to look at all at northern sky objects since those trees are too close to me and extremely tall. The limiting factor here would be about 50 degrees. When i say trees i dont mean 1 or 2, its an entire forest. Same to the east of my house, but those trees are at the other end of my backyard, so i can still view 40 degrees and higher eastwards.
My main windows are South and West, both of which i can get down to about 20 degrees maybe lower.
Oh and i didn't mean ridiculous regarding the idea of selling them, i was only referring to the price of the items. Its as if just because they're being used on a telescope instead of a house insulation, that means its more expensive. But hey, its all business right, gotta make ends meet.
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Meade 8.25"(209.55mm) LX-90 EMC (SCT)
Albert Einstein =>
“Intellectual growth should commence at birth and cease only at death.”
“If you can't explain it simply, you don't understand it well enough.”
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Octavarium
member
Reged: 08/02/08
Posts: 62
Loc: East Haven, CT
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I've had horrible dew these past few weeks in CT, all over the scope. The nights are getting cooler and less buggy though, thank god.
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Meade ETX-125PE
Series 4000 plossol eyepiece/filter set
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fastrudy
super member
Reged: 04/09/06
Posts: 164
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I live in Southampton, and it is so humid out here that I must start my dew zapper an hour before most sessions just to keep up with its formation. Yes, in Winter it is frost that forms on all surfaces ( including OTA, eyepiece, tripod). I have a dew cover thingy, but I hate using it because it flops around when slewing. I have a heating element for the corrector plate, the eyepiece and, in Winter, the handbox. I used to use a hair dryer to remove it from collector plate, but found that every little piece of pollen and dust and spider web was stuck to the corrector plate in the morning, when I could see it plainly. The heaters work fine, as long as I start before removing the lens caps.
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Protheus
Vaguely offended
Reged: 09/01/07
Posts: 4664
Loc: Illinois, US
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It seems to me that craft stores tend to carry flexible plastics for various things. they're usually white, which isn't ideal, but if you could get it in the right size, it may be worth trying. You could put a ring (made from a cable tie or something else) or two on a sheet of it cut to the right size, and that might be a perfectly good way to make a re-usable dew shield for relatively little money.
Chris
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"To tread the sharp edge of a sword;
to run on smooth-frozen ice,
one needs no footsteps to follow..."
"Well, people sometimes ask me 'how did you get involved in astronomy?' I said 'I got born, what's your problem?'" -- John Dobson
"In discussing the large-scale structure of the cosmos, astronomers sometimes say that space is curved, or that the universe is finite but unbounded. Whatever are they talking about?" -- Carl Sagan
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Achernar
Post Laureate
Reged: 02/25/06
Posts: 3727
Loc: Alabama, USA
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You wouldn't be that lucky here in the South. Dew in warmer months, frost in winter often forms within an hour or two after setting up unless I use dew heaters on the finder scopes, the diagonal mirror and the coma corrector. When they fog up, I'm shut down for the night, hence the reason for me building my own controller and heater strips. Now I can observe all night long no matter how wet it gets, short of rain moving in.
Taras
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10-inch F/4.5 Discovery Dob
6-inch F/8 Homebuilt Dob
4 1/4-inch F/4 Homebuilt reflector
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