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Greg Stone
member
Reged: 04/29/06
Posts: 80
Loc: Southeastern New England
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Hi:
Just bought a used =pair of 16X70 Fujinons and with a quick peek through a few holes in the clouds I could see immediately that they deserve the rave reviews they've received over the years.
But one thing obviously missing from them is dew shieds and before I reinvent the wheel I thought I would search this forum for some suggestions. Maybe I'm using the wrong search terms, however, for I didn't turn up anything. So - anyone have some ideas, suggestions, photographs, sources, do-it-yourself approaches, links to earlier posts - whatever? Thanks for looking.
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Canon 12X36 IS
PST
60mm Televue
16X70 Fujinon FMT
80mm Celestron Onyx
100mm ED Skywatcher (Voyager)
120mm ED Skywatcher on T-Mount
10-inch Orion Dob
15-inch Obsession Dob
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 14731
Loc: Cumberland, R I , USA42N71.4W
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Hi Greg,
simple dew shields can be made from poster board and good strong tape. You only need make it about twice as long as it is wide.
edz
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Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21
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Rich V.
Pooh-Bah
Reged: 01/02/05
Posts: 1394
Loc: Carson Valley, Nevada, USA
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Greg, I've found that the cylindrical 24 oz. size Quaker corn meal or grits containers are a perfect fit for my 16x70s.
Cut the bottoms out and the rolled cardboard bottom edge fits the objectives just fine. A little flat black paint and you're set! The plastic lid seals tight during idle time.
Rich V
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Binoculars:
33/50/75/150x100 Saturn III, 16x70 FMT-SX, 10x50 PCF-V, 10x43 DCF-SP, 10x35 E2, 7x35 E, 8x30 E2, 7x26 Custom, 8x23AS Diplomat, 8x23 Travelite
Scopes:
C9.25, 6" f8 reflector, SV80S
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Greg Stone
member
Reged: 04/29/06
Posts: 80
Loc: Southeastern New England
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Thanks for the quick response, guys - I haven't had grits in a long time. Guess it's time to try them again ;-)
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Canon 12X36 IS
PST
60mm Televue
16X70 Fujinon FMT
80mm Celestron Onyx
100mm ED Skywatcher (Voyager)
120mm ED Skywatcher on T-Mount
10-inch Orion Dob
15-inch Obsession Dob
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WOBentley
member
Reged: 09/16/09
Posts: 56
Loc: Pacific Northwest USA
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If you want something premanufactured, although they may be a bit big for 70's (advertised for 80's and bigger on Garrett site, but Orion has them in smaller sizes) then you could look at the Orion flexishields. I know they are available through Garrett Optical for their Binoculars
http://www.garrettoptical.com/SearchResults.asp?Search=dew+shields
Or direct Orion link:
http://www.telescope.com/control/product/~category_id=dew_control/~pcategory=accessories/~product_id=A0031
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My Sky; Where being blue is good...
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davidpitre
Carpal Tunnel
Reged: 05/10/05
Posts: 1824
Loc: Central Texas
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You've got a top notch pair of binoculars, you say you like them, I'd assume you'll keep them for awhile; why make dew shields out of cardboard unless you are pretty broke ?
Get some Kydex or ABS and line it with felt.
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David
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DJB
Carpal Tunnel
Reged: 02/23/05
Posts: 1589
Loc: Lisle NY
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Hi all,
I made mine from black flock paper a few years ago. Actually, I contructed two 3-4 times the stated objective diameter for an older 20x80mm Celestron made in Japan. It is a heavy seven pound monster which is hard to come by these days.
Considering the overall length, I actually made them into a semi-conical shape. This took one night to get everything the same for both sides. Perhaps this will help, even though the construction is a bit tedious.
Best regards,
Dave.
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daniel_h
sage
Reged: 03/08/08
Posts: 485
Loc: VIC, Australia
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you can make it out of PVC plumbing pipe - just check the diameter -& line them with some sticky backed felt or paint them black
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regal 10x42, 10x50ultras, 15x70 ultras, 20x80
Oly e-500, vixen 100/1000 with 0.965"/1.25",
2 old sturdy tripods for the bins (slik & velbon)
zeiss f5.6 refractor/lens (under construction)
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refractory
Pooh-Bah
Reged: 02/05/05
Posts: 1233
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How much do dew shields cut off peripheral rays coming into the objectives in typical binocular focal ratios?
Jess Tauber
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Wes James
Post Laureate
Reged: 04/12/06
Posts: 3455
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I had some scrap Protostar flocking paper... and I found a chunk of aluminum round stock from a project that was the same diameter as my TAK 22x60 bino's... I wrapped a layer of saran around the round stock- then wrapped the flocking paper around that and taped it on with a thin strip of masking tape. Then I wrapped a few layers of resin-soaked fiberglass cloth around it, and wrapped that in saran to get a smooth outer finish. Then I used a razor saw to trim the ends up- sprayed them with black paint. Slid them off, and now have a nice pair of dew shields. More work than necessary? Some might say so... to me, that's the fun of the hobby- making things and accessories for them!
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Wes
Atlantic Beach, FL
Some bino’s from Miyauchi 5x32 Binon's up through Garrett 20x110 Signature's,
Some telescopes from a Stellarvue 80mm NHNG up through a couple of 8” reflectors…
And a wonderful 4.25" Delmarva Shiefspiegler!
Some good friends, made here on C/N.
Oh- several cats and a wonderful wife!
Anyone want a cat???? :-O
"When your work speaks for itself- Don't Interrupt" -Gamble Rogers
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Sarkikos
Pooh-Bah
Reged: 12/18/07
Posts: 1063
Loc: Suburban Maryland
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Greg,
I've made many dew/light shields for my binos and scopes. I really don't understand why anyone would want to make one out of heavy material, such as metal or PVC, or a material that will degrade in dewy conditions, such as cardboard. And ABS is expensive and hard to work with. Just go to a craft store and buy thick, black foam sheeting for a few bucks. Then you can line it with the blackest, darkest felt you can find, or better yet, buy some ProtoStar flocking, because that is VERY dark and comes with good adhesive backing. Use Velcro along the long edge so you can attach and remove the shield, and make it snug tight without having to tape it to the bino or scope. You can make a nice built-in flange or indent to help position the shield on the bino/scope tube by not flocking the lower couple inches or so of the shield where it will contact the tube. The rule of thumb for refractors and binos is to make the working length of the shield extend beyond the objective lens about 2.5x the objective diameter. That will be sufficiently long to block glare and prevent dew. Anything longer would be unwieldy and may vignette the image. For Dobs, a foot long shield should be sufficient.
These shields have worked great for me. They absolutely prevent all dewing on my bino objectives and my Dob diagonals, and they virtually eliminate glare. (Fully flocking a Dob or refractor will do the rest.) The images are more contrasty, especially when I use the shields in my red zone home site. I've made about a dozen of these shields (more if you count the binos twice!), so I am speaking from experience.
Clear Skies,
Mike
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Celestron 10" f5 Newt on 1stBase (DSO)
Zhumell 8" f6 Newt, Bosma 6" f12 MCT (NSO)
6" f5 Newt, 130ST, 4.5" f4.4 Ball w/GLP, ST80 w/Crayford (RFTs)
C4-R (NSO/DS)
90mm f13 MCT (Luna/DS)
SkyMaster 25x100, 15x70
Zhumell 20x80
Barska XWA 10x50, 8x40
OptiView LPR 10x50
Const View 2.3x40
BV-125C
CG5, 2 drv / CG4, 2 drv, wood legs, ScopeStuff saddle / CG3, 1 drv
SV AZ / 501HDV on Bogen 055XB / P+ on Oberwerk
QuikFinder, Telrad
Orion Dynamo Pro 12, Dew-Not
Have GLP and not afraid to use it!
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Mike Lynch
member
Reged: 04/07/06
Posts: 52
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Let me "second" Mike's advice on the flexible foam dew / glare shields. I have done almost exactly what he has done, only the material I've used was found at a Home Depot. I think it was intended to be a thick shelf liner.
I cut pieces in the length and width I needed, spray-painted one side flat black, and added the velcro strips to allow them to be fit snugly around my 80mm bino objectives.
Another advantage: They unroll flat, making them easier to store and carry.
And, finally, by joining the ends and adding another velcro strip on the outside, they double as a dew / glare shield for the 127mm refractor I've built.
One of the best ideas I've come across! 
Mike Lynch
Frankfort KY USA
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Sarkikos
Pooh-Bah
Reged: 12/18/07
Posts: 1063
Loc: Suburban Maryland
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One advantage I've noticed for using a material with "texture" on the inside surface of the dew/light shield - such as felt or ProtoStar - is that it tends to soak up the dew that ordinarily would have collected on the objective lens. After spending as much as five or six hours or more in a heavily dewing site, my bino/scope objective will be free of any dew whatsoever, but the dew shield will be pretty well soaked! The foam/felt/ProtoStar dries out easily, though, once you remove it from the dewy site and give it a quick pat down and wiping. Just some friendly advice from experience! 
Now the eyepieces are another matter. I don't know of any easy and fool-proof dew prevention on that end. You can either keep capping the eyepiece(s) whenever you're not using them or wrap dew strips around them and keep them connected to a battery pack. If anyone has a better solution, I'd be interested. 
Clear and Dry Skies,
Mike
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Celestron 10" f5 Newt on 1stBase (DSO)
Zhumell 8" f6 Newt, Bosma 6" f12 MCT (NSO)
6" f5 Newt, 130ST, 4.5" f4.4 Ball w/GLP, ST80 w/Crayford (RFTs)
C4-R (NSO/DS)
90mm f13 MCT (Luna/DS)
SkyMaster 25x100, 15x70
Zhumell 20x80
Barska XWA 10x50, 8x40
OptiView LPR 10x50
Const View 2.3x40
BV-125C
CG5, 2 drv / CG4, 2 drv, wood legs, ScopeStuff saddle / CG3, 1 drv
SV AZ / 501HDV on Bogen 055XB / P+ on Oberwerk
QuikFinder, Telrad
Orion Dynamo Pro 12, Dew-Not
Have GLP and not afraid to use it!
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DJB
Carpal Tunnel
Reged: 02/23/05
Posts: 1589
Loc: Lisle NY
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Hi Mike,
I like your idea--I knows one when I sees it!
That this material can pick up moisture is news to me, but very welcome news, indeed. Thanks.
Best regards,
Dave.
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 14731
Loc: Cumberland, R I , USA42N71.4W
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Quote:
How much do dew shields cut off peripheral rays coming into the objectives in typical binocular focal ratios?
Jess Tauber
They don't.
Assuming you make the dew shield twice as long as the diameter of the objective lens:
Take for example a 50mm lens with an 8° field of view, an extreme example. A dew shield projecting out 100mm in front of the objective lens need only be 7mm wider on each side so as to not interfere. Wrapping the dew shield around the binocular tube gives you that extra 7mm of diameter.
I suppose if you had one of the 12° fov binoculars you might clip some rays. But that is the exception, not the rule.
A typical 20x80 with a maximum 3.5° fov needs an additional 5mm width each side of the lens for a 160mm long dew shield, so the dew shield needs to be 90mm in diameter. Any 20x80 binocular tube you try to wrap a dew shield around is going to be about 100mm in diameter.
The subject of this thread is the Fujinon 16x70. It has a 4° fov. For a dew shield projecting out 140mm in front of the objective lens, the dew shield needs to be a minimum of 80mm in diameter. The front end of the binocular tube is 98mm in diameter, so you the smallest dew tube you could wrap around it is 98mm.
edz
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Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21
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Mike Lynch
member
Reged: 04/07/06
Posts: 52
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Mike,
Hmmmmmmmm.... Interesting. I have some of the "Scope Stuff" flocking paper which I can put on my flexible bino dew / glare shields. In Central Kentucky, dew is simply a given (along with haze and fog much of the time!).
So, what's the principle here? Does the black material literally tend to "soak up" the moisture?
Mike Lynch
Frankfort KY USA
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Sarkikos
Pooh-Bah
Reged: 12/18/07
Posts: 1063
Loc: Suburban Maryland
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Mike Lynch,
The blackness soaks up the glare, but the texture soaks up the dew! What would tend to collect and hold more water, a slick surface or one made from a fibrous material with a lot of little hills and valleys? When I set up an observation table at my dark but dewy site, I cover it with a big towel to soak up the dew. Same thing. A slick surface on the inside of a dew shield in an extreme case might even allow the dew to run down in tiny rivulets onto the objective lens. Something to think about.
Mike R
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Celestron 10" f5 Newt on 1stBase (DSO)
Zhumell 8" f6 Newt, Bosma 6" f12 MCT (NSO)
6" f5 Newt, 130ST, 4.5" f4.4 Ball w/GLP, ST80 w/Crayford (RFTs)
C4-R (NSO/DS)
90mm f13 MCT (Luna/DS)
SkyMaster 25x100, 15x70
Zhumell 20x80
Barska XWA 10x50, 8x40
OptiView LPR 10x50
Const View 2.3x40
BV-125C
CG5, 2 drv / CG4, 2 drv, wood legs, ScopeStuff saddle / CG3, 1 drv
SV AZ / 501HDV on Bogen 055XB / P+ on Oberwerk
QuikFinder, Telrad
Orion Dynamo Pro 12, Dew-Not
Have GLP and not afraid to use it!
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Rich V.
Pooh-Bah
Reged: 01/02/05
Posts: 1394
Loc: Carson Valley, Nevada, USA
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Dew shields aren't about "soaking up" dew; they're about preventing radiative cooling of the lens which eventually allows moisture to condense onto it.
The objective lens gives up it's heat by radiating into cold space. Eventually the lens cools to a temperature below the ambient. Putting a tube around it cuts down the area of sky the lens "sees" and so slows down the cooling process.
If glare control is required as well, then a non-reflective interior surface helps.
Rich V
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Binoculars:
33/50/75/150x100 Saturn III, 16x70 FMT-SX, 10x50 PCF-V, 10x43 DCF-SP, 10x35 E2, 7x35 E, 8x30 E2, 7x26 Custom, 8x23AS Diplomat, 8x23 Travelite
Scopes:
C9.25, 6" f8 reflector, SV80S
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Sarkikos
Pooh-Bah
Reged: 12/18/07
Posts: 1063
Loc: Suburban Maryland
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Rich V,
Quote:
Dew shields aren't about "soaking up" dew; they're about preventing radiative cooling of the lens which eventually allows moisture to condense onto it.
The objective lens gives up it's heat by radiating into cold space. Eventually the lens cools to a temperature below the ambient. Putting a tube around it cuts down the area of sky the lens "sees" and so slows down the cooling process.
If glare control is required as well, then a non-reflective interior surface helps.
I am pragmatic. If my dew shields work by soaking up the dew - as well as by preventing radiative cooling - who am I to complain? I don't get it. They work! What's the problem? I haven't heard of any other passive solution - i.e., without an electric dew heater - that has worked to prevent dew in a very dewy site for 7 hours or longer. And I ain't afraid to point the bino or scope at zenith either, the way some amateurs are. The tube itself does cut down the area of sky the objective sees and thereby slows down the cooling process and delays dewing. But eventually when dewing forms, it is deposited first on the textured inner walls of the dew shield before it can form on the lens. And these are really dew/light shields since they also cut down drastically on glare by preventing much of the ambient light from entering in the first place, and by absorbing glare that does enter by using ProtoStar or dark black felt. A win-win solution all around. Bottom line: They work.
Clear and Dew-Free Skies,
Mike
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Celestron 10" f5 Newt on 1stBase (DSO)
Zhumell 8" f6 Newt, Bosma 6" f12 MCT (NSO)
6" f5 Newt, 130ST, 4.5" f4.4 Ball w/GLP, ST80 w/Crayford (RFTs)
C4-R (NSO/DS)
90mm f13 MCT (Luna/DS)
SkyMaster 25x100, 15x70
Zhumell 20x80
Barska XWA 10x50, 8x40
OptiView LPR 10x50
Const View 2.3x40
BV-125C
CG5, 2 drv / CG4, 2 drv, wood legs, ScopeStuff saddle / CG3, 1 drv
SV AZ / 501HDV on Bogen 055XB / P+ on Oberwerk
QuikFinder, Telrad
Orion Dynamo Pro 12, Dew-Not
Have GLP and not afraid to use it!
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StarStuff1
scholastic sledgehammer
Reged: 04/01/07
Posts: 979
Loc: South of the Mason-Dixon Line
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A while back I made dew shields out of PVC pipe for my 14x70 Fujis. Resistors were epoxied in to act as dew preventers. Altho this worked it was kind of a pain to strap batteries to the p-gram mount.
Since then I use either heat guns or dew caps made from a black foam craftie thing called Cool Foam. Cheap and EZ.
Another idea is to use rubber bands and bubble wrap to prevent dew. Looks ugly but works great.
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Tools that make objects very far away appear much closer than they actually are.
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