Archived posting to the Leica Users Group, 1999/02/16

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Subject: Re: [Leica] Leica M5(metering)
From: "Mark Hammons" <astair@ix.netcom.com>
Date: Tue, 16 Feb 1999 06:25:34 -0600

- -----Original Message-----
From: Malcolm McCullough <blayne@mbox2.singnet.com.sg>
To: leica-users@mejac.palo-alto.ca.us <leica-users@mejac.palo-alto.ca.us>
Date: Tuesday, February 16, 1999 1:46 AM
Subject: Re: [Leica] Leica M5(metering)


>
>>Osterloh in his Leica M book compares the M5 and M6 metering systems.
>>Accordingly,and here I copy his Table from p. 41:
>>                                                    M6
>>M5
>>
>>Diameter of measuring spot             12mm                  8.5mm
>>
>>Measuring range(cd/m^2)               0.25-32000           0.06-32000
>>
>>Exposure values
>>           1--18                    -1--18
>>
>>
>>Clearly, the CdS meter of the M5 is more sensitive than that of the M6.
>
>Are these measured with an f2 lens? The M6 officially measures to EV-1 with
>the Noctilux and 100 ASA film (ie 0.06cd/m^2) though I find the meter to be
>more sensitive in practice.
>Because it is a TTL meter, I think that it is more informative to quote ASA
>and shutter speed. So you would quote the M6's sensitivity as 1/2 sec with
>100 ASA film. The f-stop doesn't matter, so the EV is meaningless. Does
>anyone agree with me? Does anyone see what I am trying to get at?
>
>Regards,
>Malcolm
>


Actually, you need to express EV with film speed (typically 100 ASA is used)
AND the lens' largest F-stop (typicall 50mm F1.4).  The EV range is dependant
on both.

Mark Hammons