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."