Archived posting to the Leica Users Group, 2006/12/20

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Subject: [Leica] Filter for the M8 B+W 486
From: red735i at earthlink.net (Frank Filippone)
Date: Wed Dec 20 16:43:13 2006

If this were true......

#1.. This would affect filters in front of the lens as well.  The light 
comes from the periphery of the lens as well as the center.
Light from the periphery would be going through the filter at an angle.... 
same logic.....  THis one does not sound engineering true
to me..... I think this is Marketing nonsense coming through.....

#2... I had thought about this issue.  The original statement I made was 
that the 486 filter is a reflective filter.  The statement
that the light would be bouncing around inside the camera is correct.  While 
not good, if it is attenuated by the coatings, and it
is a small amount of light to begin with, it should not be a big deal.... 
but on this point I am still thinking.... 

However, I am not sure that Leica is not doing a marketing solution to this 
problem rather than a technical solution.  I still need
to think on this filter inside issue.

Frank Filippone
red735i@earthlink.net 



I just received the latest LFI. It contained a technical description why 
    no interference filter was used in front of the sensor. Mainly two 
technical problems.
        1) The interference that kills the IR, is based on the layer 
thickness, 
so when light rays hit the filter under an angle, the cutoff frequencies 
will shift, but also due to the nature of the filter, it influences the 
color reproduction.
        2) These filters are like mirrors which is a bad thing to have 
inside 
the camera behind the lens. It causes all kind of stray light bouncing 
inside the camera.

Meino de Graaf



In reply to: Message from meino at innerside.demon.nl (Meino de Graaf) ([Leica] Filter for the M8 B+W 486)