New Posts New Posts RSS Feed - Leaving a scope out in a heavy frost
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Check GunBroker.com for SWFA's No Reserve and No Minimum bid firearm auctions.

Leaving a scope out in a heavy frost

 Post Reply Post Reply   Topic Search Topic Search  Topic Options Topic Options
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/12/2009 at 15:32
Randall45 View Drop Down
Optics Apprentice
Optics Apprentice


Joined: June/25/2009
Status: Offline
Points: 284
Traded two Leupold VXII for a Vortex Viper since I liked how good the optics looked I  mounted and bore sighted the scope on a Winchester Model 70 300 WSM and fired 40 shots of 150 grain Winchester ballistic tips with no problems.I cleaned the rifle and left it out side on my deck which over looks a large food plot I spotted 3 coyotes 200 yards.No luck scope was fogged up because of the frost that melted.Any good advice for preventing a scope to fog.Only Bushnell Elites and Sightron S2 Big Sky have that anti-fog feature. 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/12/2009 at 21:00
Ed Connelly View Drop Down
Optics Retard
Optics Retard
Avatar
God of no Chihuahua

Joined: December/16/2007
Location: USA
Status: Offline
Points: 24220
Was it just kind of fogged up on the outside?  Or on the INSIDE??  If it is fogged up and kinda frozen on the outside it should clear up in an hour or so.....I have left rifles outside in severe cold weather ( so that scopes wouldn't fog up when I carried them outdoors)---but I usually leave them in a truck...    Bucky
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/13/2009 at 05:45
Randall45 View Drop Down
Optics Apprentice
Optics Apprentice


Joined: June/25/2009
Status: Offline
Points: 284
Originally posted by Ed Connelly Ed Connelly wrote:

Was it just kind of fogged up on the outside?  Or on the INSIDE??  If it is fogged up and kinda frozen on the outside it should clear up in an hour or so.....I have left rifles outside in severe cold weather ( so that scopes wouldn't fog up when I carried them outdoors)---but I usually leave them in a truck...    Bucky
It just happened that a frost/freeze occured causing the scope to fog on the outside, it cleared up.I usually kept my gun outside when hunting in the cold so that would prevent the scope to fog.The only scopes that don't fog up are the Bushnell Elite & S2 Big Sky.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/14/2009 at 09:32
Terry Lamb View Drop Down
Optics Apprentice
Optics Apprentice
Avatar

Joined: January/19/2009
Location: Sagle, Idaho
Status: Offline
Points: 150
The simplest solution is just to slip on one of the ScopeShield Alaska covers, as preferred by John Barsness in his previous postings. No moisture or frost on lenses or body. In theory, moisture will accumulate on surfaces that are below the current atmosphere dew point, and it will be in the form of frost if that temp is below freezing. Normally moving the scope from indoors (warm) to outdoors cold should not result in surface moisture, dew. Moving from outside cold to inside warm and humid (like an RV for instance) can result in instant dew.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/14/2009 at 18:51
burris View Drop Down
Optics GrassHopper
Optics GrassHopper
Avatar

Joined: December/31/2007
Location: Australia
Status: Offline
Points: 3

All scopes will fog up if given the conditions etc... From the warmth of a vehicle then out into the cold is an instant fog up.

Start to worry only if the interals are foggy, like my head this morning...... Whacko
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/16/2009 at 09:59
Terry Lamb View Drop Down
Optics Apprentice
Optics Apprentice
Avatar

Joined: January/19/2009
Location: Sagle, Idaho
Status: Offline
Points: 150

Aside from rain, fog, slop and goo that may fall directly on scope lenses in the field, hunters are additionally plagued by "fogging" on exterior scope lenses. Fogging is simply the condensation of water on the scope lenses and body for precisely the same reasons as forms the morning dew. The "dewpoint" of air is  the temperature at which it can no longer hold water as vapor, condensing from vapor to liquid water.

 

Humidity is the weight of water vapor contained in a defined weight of air. Warm air can hold more water vapor than cold air. When a surface such as the ground, or an auto windshield, or your scope lense cools the air touching it to the point that the air can no longer hold vapor, the water vapor condenses onto the cold surface as "fog" or frost.

 

What makes your scope surfaces cooler than the surrounding air? Interestingly, all earthly objects both absorb and radiate heat (IR) radiation. Dark colored objects absorb and radiate faster than light colored objects. The great majority of riflescopes are beautiful, basic black. Thus our black scope body will absorb heat energy rapidly from the sun, but will radiate that energy back into space at night or on dreary rainy or snowy days much faster than does the air surrounding it. (Most air being clear rather than black!) This faster loss of heat energy by the riflescope compared to the air around it, in addition to the cooling effect of physical evaporation of rain or snow water on the scope, may drop the scope temperature below the dewpoint, and, presto, everything gets covered in "fog".

 

What to do? The first step is to attempt to physically separate ambient air from the scope surfaces. Flip-up type lense covers will provide a barrier over the lenses, but allow the whole surface of the scope body to cool by evaporation, which in turn will cool the lenses. Lenses cooler than the dewpoint will fog. The more effective approach is the full neoprene cover, which keeps the ambient air and physical moisture away from the scope surfaces. This sort of "insulation" slows evaporative and radiational cooling, as well as keeping physical water from the lenses.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/16/2009 at 13:15
tahqua View Drop Down
MODERATOR
MODERATOR
Avatar
Have You Driven A Ford Lately?

Joined: March/27/2006
Location: Michigan, USA
Status: Offline
Points: 8047

I agree with some of your statements. But, heat transfer in a small aluminum object due to radiation is relatively small compared to conduction.

For example, if you bring your scoped rifle in from the cold on a sunny day versus an over cast day, the change in time from dry to condensate would not be much different. Therefore conduction is the dominant mode for heat transfer.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/16/2009 at 15:17
Terry Lamb View Drop Down
Optics Apprentice
Optics Apprentice
Avatar

Joined: January/19/2009
Location: Sagle, Idaho
Status: Offline
Points: 150
Originally posted by tahqua tahqua wrote:

I agree with some of your statements. But, heat transfer in a small aluminum object due to radiation is relatively small compared to conduction.

For example, if you bring your scoped rifle in from the cold on a sunny day versus an over cast day, the change in time from dry to condensate would not be much different. Therefore conduction is the dominant mode for heat transfer.
Conduction, which always takes place from a material of higher temperature to a material of lower temperature, is indeed the dominant mode for heat transfer until the temperatures of the two materials (the rifle scope body or lenses and the ambient air) reach equilibrium.
The discussion is directed at the phemomenon of a riflescope actually cooling below its surrounding air temperature at a rate surpassing conduction from the air.
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Similar Threads: "Leaving a scope out in a heavy frost"
Subject Author Forum Replies Last Post
scope for heavy recoil turkey gun jasperjet Rifle Scopes 5
Scope base for left hand Savage AustinN4 Rings and bases 3
Scope weight: light vs heavy? pass-thru Rifle Scopes 17
leoupold scout scope with heavy reticle ,do you ha remshooter Rifle Scopes 1
Scope for heavy recoiling rifle koshkin Rifle Scopes 8 7/4/2004 11:26:36 PM
AR-15 Heavy Barrel Scope Booger Tactical Scopes 3 9/24/2006 7:56:21 PM
CZ 527 SCOPE/ NO SCOPE? JAMINGRIZZ Rifle Scopes 16
LEFT HANDED Savage 111 30-06 SVT_Tactical Firearms For Sale 2
Duplex - Standard or Heavy gjw Rifle Scopes 1
what makes a scope a shogun scope? axaviere Shotgun / BlackPowder Scopes 5


This page was generated in 0.422 seconds.