Long term damage to light meters?

Some time ago, somewhere, somebody posted a claim that incident light
meters should never be left out of their case for extended periods as
ambient light would degrade their sensitivity over time.

Any basis for this?

Cheers,
Alan.
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In article , Alan Browne
wrote:

Some time ago, somewhere, somebody posted a claim that incident light
meters should never be left out of their case for extended periods as
ambient light would degrade their sensitivity over time.

Any basis for this?

I've never heard anything ridiculous like that. Sounds like someone on
bad drugs.

The cells could break down, I suppose, if left in bright light for
extended periods...


Alan Browne wrote:
Some time ago, somewhere, somebody posted a claim that incident light
meters should never be left out of their case for extended periods as
ambient light would degrade their sensitivity over time.

Any basis for this?

Cheers,
Alan.
--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: Remove FreeLunch.

On Sun, 12 Feb 2006 11:22:01 -0800, Randall Ainsworth
wrote:

I've never heard anything ridiculous like that. Sounds like someone on
bad drugs.

This is probably true of selenium meters on vintage gear, but I
don't recall if the damage is directly due to sunlight or from
moisture absorbed by the crystal and then freed by heat.

--
Michael Benveniste --
Spam and UCE professionally evaluated for $419. Use this email
address only to submit mail for evaluation.

I believe this is correct; selenium cell meters were always "on."

With CDS or newer type cells, this is not true.

Michael Benveniste wrote:

On Sun, 12 Feb 2006 11:22:01 -0800, Randall Ainsworth
wrote:



I've never heard anything ridiculous like that. Sounds like someone on
bad drugs.



This is probably true of selenium meters on vintage gear, but I
don't recall if the damage is directly due to sunlight or from
moisture absorbed by the crystal and then freed by heat.

Alan Browne wrote:

Some time ago, somewhere, somebody posted a claim that incident light
meters should never be left out of their case for extended periods as
ambient light would degrade their sensitivity over time.

Any basis for this?

Selenium cells do wear off in bright light. In space applications
(generating electricity for satellites) they lose 4% (IIRC) of their
capacity annually. On ground it shouldn't be that bad. But still, you
can't find old selenium meters that work correctly. Many older cameras
with selenium cells had a flip on the cell, so you could cover it when
not in use.

CdS (photoresistor) and Si (photodiode) cells shouldn't have the same
problem. They are based on different physical phenomena.

-- Lassi

All right, Lassi. We Finns agree!

Lassi Hippeläinen wrote:

Alan Browne wrote:


Some time ago, somewhere, somebody posted a claim that incident light
meters should never be left out of their case for extended periods as
ambient light would degrade their sensitivity over time.

Any basis for this?


Selenium cells do wear off in bright light. In space applications
(generating electricity for satellites) they lose 4% (IIRC) of their
capacity annually. On ground it shouldn't be that bad. But still, you
can't find old selenium meters that work correctly. Many older cameras
with selenium cells had a flip on the cell, so you could cover it when
not in use.

CdS (photoresistor) and Si (photodiode) cells shouldn't have the same
problem. They are based on different physical phenomena.

-- Lassi

Lassi Hippeläinen wrote:

capacity annually. On ground it shouldn't be that bad. But still, you
can't find old selenium meters that work correctly. Many older cameras


I've got a Westonmaster V which works fine.

Thanks, everyone, for your replies. In summary it would appear that
this applies to the no longer common selenium meters.

I do keep my meter in its case, normally, but occasionally leave it out
in the "studio" where it might sit for a week or so before I put it away.

Cheers,
Alan.

Alan Browne wrote:


Some time ago, somewhere, somebody posted a claim that incident light
meters should never be left out of their case for extended periods as
ambient light would degrade their sensitivity over time.

Any basis for this?



--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: Remove FreeLunch.