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#39857 - 04/15/05 05:56 AM Fresnel lens?
fordwillman Offline
Member

Registered: 08/27/04
Posts: 103
Loc: Arizona
Anyone have any experience using a plastic Fresnel lens to create a fire? If I were to purchase a sheet of this stuff to try, what do I need to look for? Is there much difference?

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#39858 - 04/15/05 06:05 AM Re: Fresnel lens?
rodmeister Offline
new member

Registered: 03/23/02
Posts: 54
Loc: ca
I started a fire in my back yard using leaves and paper. I used a 2 1/8" x 3 1/4" "ITOYA POCKELENS" fresnel lens I kept in my wallet for years. Bought it in a book store. Despite late 4PM sunshine I got a flame going without using tinder in about 10 seconds by just blowing on the smoking hole created by the lens. I have a larger one about 4"x6" but a sheet isn't necessary. BTW newsprint lights almost instantly.

It's a great backup or secondary survival fire starter since it takes no more room than a credit card. Of course you need to get the fire going before sundown. Perhaps the larger fresnel would allow one to start a fire closer to sunset.

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#39859 - 04/15/05 07:00 AM Re: Fresnel lens?
paulr Offline
Addict

Registered: 02/18/04
Posts: 448
The waller sized ones are kind of hard to start fires with. The big ones (notebook sized) are so easy it's ridiculous, those things are downright dangerous. However, when you need a fire the most, there's probably no direct sunlight available. You're better equipped with a more normal firestarter.

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#39860 - 04/15/05 01:14 PM Re: Fresnel lens?
GoatRider Offline
Old Hand

Registered: 08/28/04
Posts: 818
Loc: Maple Grove, MN
rodmeister,

What latitude are you at? I'm at 45 north (twin cities MN), and early last fall I gave firemaking a try with fresnel lenses, and didn't have much luck, and certainly not with the credit card sized ones.

A fresnel lens is useful if you bring a small survival handbook and normally need reading glasses. The lens can serve as a backup to your reading glasses. Their use as a firestarter is secondary.

I found one place to order them online: http://3dlens.com/
_________________________
- Benton

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#39861 - 04/15/05 04:11 PM Re: Fresnel lens?
brian Offline
Veteran

Registered: 07/28/04
Posts: 1468
Loc: Texas
Quote:
when you need a fire the most, there's probably no direct sunlight available
Yep thats my problem with them. When I need a fire its dark, dreary, cloudy, windy and rainy.
_________________________
Learn to improvise everything.

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#39862 - 04/15/05 05:46 PM Re: Fresnel lens?
M_a_x Online   happy
Old Hand

Registered: 08/16/02
Posts: 949
Loc: Germany
I carry a credit card sized one. In summer it works well. In the winter it mandatory to have the proper tinder. I found that fungi from tree work great. Once they start smoldering they keep going and when you blow gently the ember gets hot enough to ingite cotton or dry grass.
Itīll be a really hard day if I ever need to use it for firestarting as I carry enough other means for that purpose. I carry the lens as magnifying glass. Other poster already mention why.
_________________________
If it isnīt broken, it doesnīt have enough features yet.

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#39863 - 04/16/05 01:54 AM Re: Fresnel lens?
rodmeister Offline
new member

Registered: 03/23/02
Posts: 54
Loc: ca
Goatrider, I live in the Venice District of Los Angeles, CA, near the beach. I tried my experiment in winter at around 4PM. I was surprised how well the credit card sized fresnel worked. But I can understand it failing at high latitues, especially in the cold.

I will take my 4x6 inch fresnel at higher latitues. And you're right, I never count on it has a primary fire starter. I think everyone can agree on the foolishness of that. It's only for use as a last-ditch solution. I carry the card for presbyopia.. "old peoples eyes."

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#39864 - 04/16/05 04:02 AM Re: Fresnel lens?
rodmeister Offline
new member

Registered: 03/23/02
Posts: 54
Loc: ca
But I wouldn't use that as an excuse not to carry a card sized fresnel. It's a backup or secondary or tertiary fire source for when you lose your matches, lighter, flint, or whatever.

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#39865 - 04/16/05 06:24 PM Re: Fresnel lens?
M_a_x Online   happy
Old Hand

Registered: 08/16/02
Posts: 949
Loc: Germany
A backup should be reliable and possibly not fail for the same reason as the primary item. The fresnel lens lacks the reliability in most scenarios where you would need a fire. Maybe it would be better not to consider it as a fire source unless you have no choice or donīt actually need the fire promptly.
I second the advice to carry one though. I used mine for many purposes including first aid. The small size and weight are hardly noticeable and worth it.
_________________________
If it isnīt broken, it doesnīt have enough features yet.

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#39866 - 04/17/05 03:26 AM Re: Fresnel lens?-Water lens.
bountyhunter Offline


Registered: 11/14/03
Posts: 1224
Loc: Milwaukee, WI USA
I read somewhere on the web that it is possible to make a lens out of a clear plastic bag of water on a plate of glass or clear hard plastic sheet.

You supposedly fill the bag with clear water, put it on the glass plate in such a way that the bag is convex at the top while being flat on the glass at the bottom and concentrate the incoming sunlight in that manner.

Any one on here ever try it?

Bountyhunter

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