[rollei_list] Re: Hello (again), new Rollei TLR

----- Original Message ----- 
From: "Ardeshir Mehta" <ardeshir@xxxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Friday, April 29, 2005 12:25 PM
Subject: [rollei_list] Re: Hello (again), new Rollei TLR


>
> On Friday, April 29, 2005, at 02:26  PM, Marc James Small 
> wrote:
>
>> My heavens, Jerry!
>>
>> Learn to estimate exposure.  Sunny 16 rules!
>>
>> Don't need no steenken' meter!
>>
>> Marc
>
> Darn right, Marc! I do have a Weston Master II but hardly 
> ever use it,
> even for Velvia 50, and DEFINITELY not for B&W. My 
> exposures are almost
> always spot-on. When I feel doubtful, I take two shots 
> with different
> exposures of the same subject, and thereby make up for it.
>
> Cheers.
>
>
> Ardeshir <http://homepage.mac.com/ardeshir>
>
   Beware of two problems with Weston meters: The first is 
that the angle of view is very wide. This may give you false 
readings when outdoors if you are not careful to avoid too 
much sky in the reading. When used for close reflection 
readings they are very good.
   The second problem is with older meters calibrated in 
Weston speeds. While these translate to the next higher 
ISO/ASA speed the calculator seems to have been designed to 
remove a safety factor in the speeds. I have several Weston 
meters all with good cells. All underexpose if the Weston 
equivalent of an ISO speed is entered. I find they are right 
on when half the speed is entered. What I suspect is that 
for some reason Weston put a 2X safety factor in their 
speeds and then took it out again in the calculator. I have 
no idea why this might have been done.
  The Weston speed system was the first independant speed 
rating available. Speeds were measured by Weston and 
published periodically in a booklet. Previous speed methods 
were such that they could easily be fudged by the 
manufacturer usually indicating the film was faster than it 
was. A number of other meter manufacturers adopted the 
Weston speed system. The exception was General Electric. I 
have never seen a description of the GE speed method. Older 
GE meters calibrated in the GE speeds should be set for the 
next higher number than the ISO speed. There doesn't seem to 
be any juggling of values in the calculators. Both Weston 
and GE meters are capable of giving accurate exposure 
information provided the cells are OK. The usual symptom of 
a bad cell is low readings at the high end of the scale. 
Weston meters are easy to test because the same light level 
can be read at both the top and the low end of the scale. 
The values should be very close. Bad cells typically read 
about a stop low at the high end.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 

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