Archived posting to the Leica Users Group, 2006/06/11

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Subject: [Leica] Just back from India, question about burning hole in shutter
From: walt at waltjohnson.com (Walt Johnson)
Date: Sun Jun 11 17:57:07 2006
References: <C0B224A4.11E6E%bdcolen@comcast.net>

Well B.D., there's that book learnin and then that good ol common sense. 
Sometimes the real smart ones get so hung up on all that mental jerkin 
off they  kinda miss the point of  where they got started.

Walt

B. D. Colen wrote:

>Damn! And here I always thought that closing the lens down focused the light
>and burned a hole....Of course what you say about the light and heat is
>totally logical...and Lord knows you can burn paper with a big ass
>magnifying glass... ;-)
>
>
>On 6/11/06 6:16 PM, "Walt Johnson" <walt@waltjohnson.com> wrote:
>
>  
>
>>Philippe
>>
>>You burn holes in shutters at wide open apertures. so the smaller the
>>aperture the small the risk..BTW f16 is much smaller aperture than
>>f1.5...bigger number but smaller hole... ;-)
>>
>>Walt
>>
>>Philippe Orlent wrote:
>>
>>    
>>
>>>Weren't you saying then -contrary to me- that the smaller the lens
>>>opening was, the higher the risk?
>>>If not, then I misinterpreted you from the start.
>>>
>>>
>>>Op 11-jun-06, om 17:56 heeft Walt Johnson het volgende geschreven:
>>>
>>>      
>>>
>>>>It seems simple....light=heat....less light=less heat....f16 is  less
>>>>light (heat) than f1.5...Voila..Elementary my Dear Philippe :-P
>>>>
>>>>Philippe Orlent wrote:
>>>>
>>>>        
>>>>
>>>>>Damn Walt, you got me thinking and testing.
>>>>>Took a Summarit and burned within 1 sec a hole in a newspaper page
>>>>>at  f 1.5.
>>>>>The distance was about the one to focal plane.
>>>>>Did it again at f 16. A smaller circle on the newspapern but no
>>>>>burning even at 10 secs.
>>>>>I also think I know why. Do you?
>>>>>;-)
>>>>>
>>>>>
>>>>>Op 11-jun-06, om 14:56 heeft Walt Johnson het volgende geschreven:
>>>>>
>>>>>          
>>>>>
>>>>>>Vick
>>>>>>
>>>>>>Simply take the lens off and outside to find the solution to  your
>>>>>>question. Focus the sun on your arm  stopped down and wide  open
>>>>>>and  prove to yourself which is more likely to burn the  shutter
>>>>>>curtain.
>>>>>>
>>>>>>Walt
>>>>>>
>>>>>>Vick Ko wrote:
>>>>>>
>>>>>>            
>>>>>>
>>>>>>>I am just back from a very interesting trip to Bangalore (too
>>>>>>>few  days, but
>>>>>>>in a way, just enough days).  Interesting to see the thread on the
>>>>>>>temples...hmm.
>>>>>>>
>>>>>>>I was visiting my workteam, and a bit of sightseeing.  The
>>>>>>>camera  on my trip
>>>>>>>was a Leica CL.
>>>>>>>
>>>>>>>One question, on one day, my workteam took me out to  play
>>>>>>>cricket  and when
>>>>>>>it was "team photo" time, one of the guys took our cameras
>>>>>>>(there  were 2 of
>>>>>>>us), stood back and took our photos.  My camera was at f16, and
>>>>>>>I  noticed
>>>>>>>that he put it face up on the ground.
>>>>>>>I had thoughts of horror as I worried about the sun burning a
>>>>>>>hole  into the
>>>>>>>shutter.  I did notice that he wound the film on, so I think at
>>>>>>>least there
>>>>>>>was a chance of the sun, coming in at f16, hitting the meter.
>>>>>>>
>>>>>>>So my LUG questions:
>>>>>>>
>>>>>>>1. can the sun at f16 burn a hole?  I'm not wanting to try the
>>>>>>>experiment
>>>>>>>
>>>>>>>2.  can the sun at f16 hurt my CL meter?  It seems fine.  I
>>>>>>>suspect the sun
>>>>>>>is not at its focal point for the meter face
>>>>>>>
>>>>>>>I did notice a discoloured patch that is off to the edge of the
>>>>>>>shutter, 1/4
>>>>>>>of the way to the edge.  It doesn't look like the sun "melted"
>>>>>>>the  rubber
>>>>>>>there, maybe it was there always.
>>>>>>>
>>>>>>>Thanks in advance.
>>>>>>>
>>>>>>>Regards,
>>>>>>>
>>>>>>>Vick Ko
>>>>>>>
>>>>>>>-------------------------------------------------------------------
>>>>>>>-- ---
>>>>>>>
>>>>>>>
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>>>>>>>Leica Users Group.
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>>>>>>>
>>>>>>>              
>>>>>>>
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>>>>>>            
>>>>>>
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>>>>>
>>>>>
>>>>>          
>>>>>
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>>>>        
>>>>
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>>>      
>>>
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>>    
>>
>
>
>
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In reply to: Message from bdcolen at comcast.net (B. D. Colen) ([Leica] Just back from India, question about burning hole in shutter)