Guest WPalank Posted March 4, 2007 Share #1 Â Posted March 4, 2007 Advertisement (gone after registration) So I'm sitting in trendy Malibu Beach Bar after a shoot with a client and we are enjoying glass of wine overlooking a magnificent view of the ocean when I notice a laser dot on my lens cap (my M8 was around my neck) which was laying next to my glass. I thought wow that's cool, so I took a snap. The brilliant red light was due to some sort of refraction or reflection through the glass of Cabernet (California) and out the bottom of the stem. Â The lens cap couldn't of been there for more than 5 minutes when I picked it up to put it back on the lens. I noticed what seemed to be a wet spot which I tried to wipe off, but to no avail. On closer inspection I noticed a divot as if the the cap had melted in a very precise area maybe 4mm wide. I quickly gave stink eye to the client as he was smoking a cigar, but I looked and all the ashes were in his ashtray along with the burnt matchstick, then it hit me. Â I showed him the pic I had taken of the red laser like light and the lens cap at which point we both remarked that the melted divot and the red dot were in the same exact position. We then started to run a couple of experiments (OK, we were bored!). I started with my finger (yeah, sometimes I'm not the brightest tool in the world) but felt absolutely no heat even after a couple of minutes. Then I went to an unlit match, centering the light at the tip (it was white) and about the same height as the cap and it didn't burst into flames like I hoped. Then I felt it was the color (black) and not wanting to sacrifice my lens cap once again (can you say Leica) I found a dark peice of paper. Again, nothing burst into flames and absolutely no heat! Â So what the heck happened? As Rod Steiger would say on his show "The Twilight Zone", "Submitted for your approval......" Link to post Share on other sites More sharing options...
Advertisement Posted March 4, 2007 Posted March 4, 2007 Hi Guest WPalank, Take a look here Weird Science and a 50 Lux Lens Cap. I'm sure you'll find what you were looking for!
Guest guy_mancuso Posted March 4, 2007 Share #2  Posted March 4, 2007 Wow they only thing that immediately comes to mind is a chemical reaction to the light. It certainly looks like it melted  Stop hanging out in trendy Malibu Bars may help. LOL Link to post Share on other sites More sharing options...
jaapv Posted March 4, 2007 Share #3 Â Posted March 4, 2007 As you can see that glass acted as a lens for the sun, burning a hole in your lens-cap. All other things, the paper, your finger, etc, were probably out of focus, but the lens cap just happenend to be in the hot spot. Now just imagine what a real lens can do to your shutter (Titanium burns as easily as cloth...) Link to post Share on other sites More sharing options...
farnz Posted March 4, 2007 Share #4 Â Posted March 4, 2007 William, Â I think you were close with your explanation but there are a couple of factors that you didn't take into account. Â The red wine absorbs some of the sun's radiant energy, that's why it gets warm after awhile, so there is less energy when the rays reach the table; ie the wine glass was acting like an inefficient lens. Â The melting point of plastic (or in this case a synthetic polymer - probably medium density polyethylene) is low, around 120C, whereas ignition temperature of paper is higher at around 230C. My guess is that the surface temperature was between 120 and 230C so the cap melted but the paper didn't burn. Â You said that there was a 'laser dot' on your lens cap so the light from the wine glass must have been reasonably focussed but if you'd used a lens instead I think the paper would have burned. Â This leads to a note of warning: if your lens cap was on the table it was not on your lens because the M8 was around your neck. There's a risk of your lens focussing the sun's rays onto your shutter and damaging it. Â That's my tuppenceworth. Â Pete. Â Seems like Jaap's and my posts crossed. Link to post Share on other sites More sharing options...
Guest WPalank Posted March 4, 2007 Share #5 Â Posted March 4, 2007 Stop hanging out in trendy Malibu Bars may help. LOL Thanks Guy,I can only try! Â :: Jaap, But I really spent some time at it narrowing the beam at the approximate height and felt nothing! I agree, it's the obvious answer, but absolutely no heat! I think there is something else in the equation. Also, there was not whiff of smoke coming from the cap and I had touched it immediateluy after lifting it off the table and again, it was not hot. It brought me back to the days of a young child setting leaves on fire with a magnifying glass but you could always see the smoke. Â Moral of the story: Don't drink and shoot! Link to post Share on other sites More sharing options...
nryn Posted March 4, 2007 Share #6 Â Posted March 4, 2007 Yep. The sun shining through your wine glass created a focus point on your lens cap. The red color is a result of the wine being red. Â You could probably kill ants using the same method... Link to post Share on other sites More sharing options...
Guest magyarman Posted March 4, 2007 Share #7 Â Posted March 4, 2007 Advertisement (gone after registration) If I will be sit in kaffe and see red spot from laser on mine camera what stay front of mine heartz I gonna crop in mine pants and go fast under table Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted March 4, 2007 Share #8 Â Posted March 4, 2007 Hell I see a laser anywhere near me i am running. It could be from a gun. LOL Link to post Share on other sites More sharing options...
ho_co Posted March 4, 2007 Share #9 Â Posted March 4, 2007 Guy's right. You just got a warning. Someone was saying, "This is what I can do with Leica lens caps on the table. Think what I could do if I pulled the trigger. Stay out of Malibu Beach, photographer! This is my territory." Â --HC Link to post Share on other sites More sharing options...
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