[rollei_list] Re: OT: cds vs. selenium
- From: ERoustom <eroustom@xxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Mon, 6 Aug 2007 20:16:02 -0400
Thank you. That makes sense now.
Elias
On Aug 5, 2007, at 11:14 PM, Marc James Small wrote:
At 10:44 PM 8/5/2007, ERoustom wrote:
>> I suspect that part of the canard of inaccuracy comes from the
>> reality that we have institutionally forgotten that a selenium
>> meter needs to be used differently from the manner in which a CdS
>> or later meter is employed. LEARN how to use a selenium meter and
>> it is perfectly suitable.
>
>Could you give a novice a hint or two on the differences in using the
>two?
Selenium offers a metering material which more closely matches the
response range of chemical emulsions than do later materials such
as CdS, SPD, or Gallium Arsenide. But selenium requires a wider
acceptance angle -- no one has yet manufactured a one-degree
Selenium spot meter!
Accordingly, you have to average a good deal. This generally
requires more attention to what is being metered coupled with
sweeping the meter up and down and side to side to obtain an
average reading. The reading so obtained should be quite usable.
Marc
msmall@xxxxxxxxxxxx
Cha robh bàs fir gun ghràs fir!
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