@Rolleiflexible , When you “calibrate” are you mostly verifying agreement/disagreement and documenting the difference? That’s what I’ve done. Doing lab calibration or actually adjusting the meter so they all read exactly the same isn’t something I’d undertake.
I have seen you say this in various threads. I disagree. As a photographer, my only interest is a repeatable process. If my meter is off, that’s okay so long as it is consistently off. When I get a new meter, I calibrate it to the old meter. It works just fine for me. Maybe it wouldn’t for you but that’s not my problem.
I've found working on old selenium meters to be rather hopeless: there is dust in the movement's pivots so it hangs up now and then; the needle trap moves the needle; the needle scrapes on something; the wires are rotted; the cell leaks current ... Westons, in my experience are the worst offenders, though when new they were the nicest of the old-school meters.
You’re not wrong. I started this project with a few nicely working Westons, so I thought it would be fun. I thought there would be a good yield. Looks like the yield is close to three out of twenty.
I thought loose nuts making poor contact would be the root cause of many. But it turns out rare.
Needles are rarely a problem. I’d say if untampered, nine out of ten have good movements. The meters are well sealed with an o-ring on the top and a rubber gasket on the back. Dusty samples are rare. The magnetic dust can be picked off with a toothpick tipped with a little contact cement. There are no wires to speak of, they join the coil directly to the copper ring. And a copper band or steel strand makes the positive contact.
The chief failure though is the Selenium cell.
I have not found a way to revitalize Selenium cells. Yesterday a “dead one” threw out 90 microamps when I touched a wire to a random spot in the middle of the front. I can’t rely on that.
The 'zero adjust' screw isn't going to make for a good calibration adjustment.
The meter scale is non-linear. Turning the screw so it yeilds a 1/2 stop change at the middle of the scale will cause a 1 stop change at the low end and a ten stop change at the very low end (Sekonic 398M).
If a meter consistently reads a 1/2 stop off it is best to adjust the ASA setting to compensate. If the meter error is inconsistent a new/old meter might be the best solution.
It doesn’t work.And I'll drag out the old chestnut about re ionizing Selenium Cells that's been floating around the Interwebs for a while:
Can't say if it works or not, but I guess I should try it sometime...
It doesn’t work.
Come on, ketchup Coke, baking soda, vinegar???? It just ruins them.
There is a single-atom layer of gold deposited on top of the cell.
I think a real solution will require gold deposition in a vacuum.
But I might try strands of gold leaf on the cell that almost works.
It doesn’t work.
Come on, ketchup Coke, baking soda, vinegar???? It just ruins them.
There is a single-atom layer of gold deposited on top of the cell.
I think a real solution will require gold deposition in a vacuum.
But I might try strands of gold leaf on the cell that almost works.
This is my trusted "light" meter.
View attachment 259840
Well… the general intent might work. Those substances as cleaning agents is ridiculous.
I’ve revived a Weston III simply by cleaning the copper contact ring very gently for a better contact. It was a long time ago and I don’t recall what I used but if I guess it was a very mild rubber eraser. The meter is still in service and accurate within reason.
In Sanders World,
I can't help myself. Whenever I see this thread's title, I think of something else.....
For some, what you describe as "Sanders World" is akin to purgatory!
I'd be more than happy to spend lots of time there.
But it frightens me to think of young photographers who come to these forums looking for guidance, and read about how you should never shoot without a tripod, or how stand processing is unreliable, or how you need to send out your light meters for calibration, or how the Zone System rules, etc., etc. It’s off-putting to a newbie, and it is a fussiness about shooting film
I’ve always liked what I read Adams said about Weston’s method. Take a reading and add one stop. Good enough.
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