[pure-silver] Re: Off topic, Spot meter problem

  • From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
  • To: <pure-silver@xxxxxxxxxxxxx>
  • Date: Tue, 20 Oct 2009 17:30:53 -0700
----- Original Message ----- From: "John Stockdale" <j.sto@xxxxxxxxxxx> 
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Tuesday, October 20, 2009 2:39 PM
Subject: [pure-silver] Re: Off topic, Spot meter problem



Tim Daneliuk wrote:

<edited>
But - and here is the important part - "accuracy" isn't really all that important. *Repeatability* is. When you do Zone System calibration to find your "personal ASA", you're effectively compensating for any inaccuracy in the meter. However, this only works 
if the meter is "consistently inaccurate" (repeatable).
Now, both the meters I had/have were pretty much bang on (accurate) AND very, very repeatable even after years of use. Whether or not they solve the problem of correctly metering through filters - the claim that Zone VI fixed this - is an exercise left to the reader.
Back in the Fred Picker days, I bought two of his modified Pentax digital spot meters. Although they have been treated gently, for some years their readings drifted apart. They are both different to a whole lot of good meters that more or less agree with each other. Instead of having them recalibrated here at the end of the Earth, I just alter their ISO settings to make them agree with the other meters, and all is fine (subject to a small mental adjustment because one is slightly non-linear). I wonder if the non-modified meters would have been more stable. 

Apart from that, excellent meters.
Tim's comments about WD-40 are interesting. I had been told some conflicting advice, but I will use it with more confidence in the future. 

John
If the batteries are conventional dry batteries the paste inside is alkaline not acid. Its still very corrosive. I suggest cleaning out the battery case with warm water with perhaps a bit of dishwashing detergent in it. Get as much as you can of the battery residue out, preferably all of it. Baking soda past is suggested for automobile batteries but they are acid. Nonetheless, a baking soda paste may be helpful with caked residue. Once the battery residue is removed the corrosion can be removed with a past made of Barkeeper's Friend or similar or Tarn-X. Even tile cleaner can be helpful, but any residue of any of these must also be completely removed. Contact cleaner like Caig De-Oxit can be used sparingly _after_ cleaning. I've tried WD-40 as contact cleaner and found it was not as effective as De-Oxit. A pencil eraser will work as a very mild abrasive for cleaning contacts. 

--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 
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