Magnifying glasses - Yes or no?

[Spark]

I found that the standard magnifying glass lens sucks, and not worth the effort unless you are willing to use a really really big and heavy one.

That is, until I found these neat little ones at the book store. They are a flat piece of plastic and can be had in credit card size or larger, and wow do they get things hot in a hurry.

They work by using concentric rings to focus the light without being thick (similar to overhead projectors), and they work quick.

Tradeoffs of course are low and no light, which is why this isn't a primary fire starting tool

but since they don't weigh anything, they certainly are worth checking out. If anything, they go fast...

Anyone else have experience with these?

Spark

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Kevin Jon Schlossberg
SysOp and Administrator for BladeForums.com

Insert witty quip here

 

[Michael Bennett]

The flat lenses are Fresnel lenses.

I carry one in my backpack. And you're right - they're a decent backup for daylight firestarting. When we were kids, we used magnifying lenses to start fires with punk wood or Horse Chestnut leaves. Both of these begin burning quickly, and produce a smoldering ember that can be blown into a flame when placed against tinder.

Mike

 

[Donald]

Spark,

Good tip. Amazing. I found it worked better on darker tinder, such as tan bark. It did work on white paper, but I was unsucessful with cotton. I tried my sparker, which I keep on my key chain, and it (the stubborn cotton ball) lit right away. I imagine it would work with a lot of effort, but for those who rush out and try this like I did, don't give up because one type of light colored tinder does not react well.

I imagine this would work with char cloth or charred cotton balls. I have to make some as soon as I am finished with my shoe polish tin. That was a good tip for the source of a tin, in another thread (cannot find the reference right now though). What I plan on doing is drilling a small hole on the side. When lined up I can heat it. For storage, turn the lid to close the hole. (Another good tip I read...from the Hoodlums forum???)

I imagine one advantage of having a fresnel lens along would be to help dry out damp tinder. It also works to light your match if the striker is damp.

Anyone have an idea what size hole would be best? Too small and perhaps I might get a pop..which might be dangerous. Too large and it won't work because there will be too much oxygen.

[This message has been edited by Donald (edited 02 December 1999).]