Point Arena, south of Mendicno has a lighthouse you can tour, go up to
the lens room and rent rooms in the keepers quarters.
See: http://www.mcn.org/1/palight/

Todd
'88 Westy

PS. As was mentioned by other posters,  Don't forget to bring

" your bullet proof vest, my passport, foreign language translation dictionary, gun - for negotiating
traffic, and your NPR card."  :-)

Ben McCafferty wrote:

>While we're on the topic of Fresnel lenses, those of you in or near CA, take
>a trip in your Westy (RVC) to the Pigeon Point Lighthouse, about 15 miles
>south of Half Moon Bay.  You can take a tour, and they are one of the only
>lighthouses I know of where you actually get to go up into the top where the
>Fresnel lens is.  It is an order 1 lens (I think--it's the biggest one ever
>made), and is nothing short of spectacular.  Once a year, in November, they
>light the bulbs inside the lens and it is a working Coast Guard beacon for 2
>hours.  Other times, the have a modern spotlight that rotates.  It is
>magnificent--24 beams of light in all directions, slowly rotating.....it's
>like being under a giant umbrella.  And there's a hostel there, so you can
>camp or get a bunk.
>bmc  :)
>"Faith will move mountains, but you'd better bring a shovel...."
>
>
>>From: Dan Snow <dieselvanagon@HOTMAIL.COM>
>>Reply-To: Dan Snow <dieselvanagon@HOTMAIL.COM>
>>Date: Wed, 8 May 2002 00:19:44 -0700
>>To: vanagon@GERRY.VANAGON.COM
>>Subject: Re: fresnel lens
>>
>>My dad brought one home when I was a kid, I think it was from an old
>>overhead projector. On sunny days in Colorado Springs (~6300 ft elevation) I
>>could spot weld coins together with it. And I don't mean sit around for an
>>hour and wait for things to heat up. I mean put on welding goggles, bring it
>>into focus on a stack of coins, and almost instant molten pennies. If you
>>ever see an overhead projector at a thrift store or junkyard, I HIGHLY
>>recommend getting the lens. It beats frying ants and beetles (VW Content?)
>>with a little reading glass.
>>
>>
>>>From: John Carpenter <Trvlr2001@AOL.COM>
>>>Reply-To: Trvlr2001@AOL.COM
>>>To: vanagon@GERRY.VANAGON.COM
>>>Subject: fresnel lens
>>>Date: Tue, 7 May 2002 18:37:53 EDT
>>>
>>>Question
>>>
>>>I have a thin piece of plastic mounted on the back window of my RV. It
>>>magnifies things so I can see better when I am backing up. Why can such a
>>>thin piece of plastic magnify things? A normal glass magnifying lens would
>>>have to be curved on both sides and would be much thicker. Answer
>>>
>>>
>>>
>>>
>>>If you have ever looked at the lens of a magnifying glass, you know it is
>>>thick in the middle and tapers to nothing at the edges. In other words it
>>>is
>>>shaped like a lentil, which is where the word lens comes from. It would not
>>>be very easy to make a big magnifying glass lens for your RV because it
>>>would
>>>be thick, heavy and hard to mount. The thin piece of plastic you are using
>>>is
>>>called a Fresnel lens. It is flat on one side and ridged on the other.
>>>Fresnel lenses we first used in the 1800's as the lens that focuses the
>>>beam
>>>in lighthouse lamps. Plastic Fresnel lenses are used as magnifiers when a
>>>thin, light lens is needed. The quality of the image is not nearly as good
>>>as
>>>that from a continuous glass lens, but in lots of applications (like your
>>>RV)
>>>perfect image quality is not necessary. The basic idea behind a Fresnel
>>>lens
>>>is simple. Imagine taking a plastic magnifying glass lens and slicing it
>>>into
>>>a hundred concentric rings (like the rings of a tree). Each ring is
>>>slightly
>>>thinner than the next and focuses the light toward the center. Now take
>>>each
>>>ring, modify it so it flat on one side, and make it the same thickness as
>>>the
>>>others. To retain the rings' ability to focus the light toward the center,
>>>the angle of each ring's angled face will be different. Now if you stack
>>>all
>>>the rings back together, you have a Fresnel lens. You can make the lens
>>>extremely large if you like. Large Fresnel lenses are often used as solar
>>>concentrators.
>>>
>>>
>>
>>
>>
>>Daniel Snow
>>
>>'82 Vanagon Diesel
>>'78 Puch Maxi Luxe Moped
>>'01 Xootr Scooter
>>http://faculty.haas.berkeley.edu/snow/vanagon/vanagon.html
>>
>>
>>_________________________________________________________________
>>Chat with friends online, try MSN Messenger: http://messenger.msn.com
>>
>