625 Voltage Readings

[nikon_sam]

Okay here's my question/concern...
I have several NOS Mercury Batteries GM625 1.35V (Replaces EPX625, PX625 & RM625) Batteries have been kept in the frige...
Three are still in the original packaging and they read 1.492VDC using a Fluke 77 multimeter...The other four of which two are in a Gossen Luna-Pro read 1.470, 1.462, 1.465 & 1.457
These last four have been used but are still above the 1.35V they are rated at...
Now the Gossen takes two batteries so together the voltage is around 2.925VDC. Is this extra voltage having any affect on it's readings? Should I be concerned or am I wasting my time worrying about this...
A side by side comparison with a Luna Pro sbc (9V battery) shows...


Incident Reading......Luna-Pro EV-17......Luna-Pro sbc EV-19
(In full sun)


Reflected Reading......LP EV-17.5.................sbc EV-18
(Bricks in full sun)


Incident Reading
(Under shaded patio).....LP EV-11................sbc EV-13.5


Reflected Reading.........LP EV-13.25.............sbc EV-14
(Bricks in shade)

Neither of these two meters have had any normal service since I've owned them but have had their needles Zeroed out by me.
The only thing I did to the Luna-Pro was many years ago I sent it to Zone VI Studios for service(?) I had the Zone System scale added to the meters dial so I'm not sure if they adjusted anything else inside the meter while they had it.
I'm also thinking that before using these meters again I should send them in...
I also did a quick comparsion, with a just serviced Weston Master II, of the two Gossens...they were close with the Weston somewhere between the two others...
Any feed back would be appreciated...

 

[colyn]

A battery will show more than the listed voltage but drops to proper voltage once a load is placed on them so your meter won't suffer false readings.

 

[nikon_sam]

Colyn,

I thought of that too...
Maybe I should ask...Does anyone have two different meters with the exact same meter readings??? And how much is too much in comparing the two readings???

 

[FallisPhoto]

Colyn,

I thought of that too...
Maybe I should ask...Does anyone have two different meters with the exact same meter readings??? And how much is too much in comparing the two readings???

I've never had two that, out of the box, agreed with one another exactly, although they might be pretty close. Only time that has happened with me was when one meter was used to calibrate another.

 

[ferider]

Colyn,

I thought of that too...
Maybe I should ask...Does anyone have two different meters with the exact same meter readings??? And how much is too much in comparing the two readings???

While I have different meters reading differently (upto 1 stop difference),
I have groups with the same reading. My two CV Mini meters and my two M6 bodies coincide within half stop (which is about the measurement accuracy).

My Gossen Lunasix and Gossen Multi-Pro match with each other but are a little less than a stop off when compared with the others.

All with new and modern batteries.

I decided to live with it and adjust when I shoot.

Roland.

 

[raid]

It is for such reasons that I have been using a Pentax digital spotmeter forever it seems. It takes 6V batteries that fit my Canon F1N, so I always had as a back-up my meter and/or camera for the other.

 

[Al Kaplan]

A couple of weeks ago I got my two Weston Master V meters back from complete overhauls at Quality Light-Metric and yes, they matched exactly. They probably won't stay that way for long. They don't require batteries so at least there's no worries about battery voltage.

 

[kuzano]

Spend $10 and get your answer....

Spend $10 and get your answer....

Buy 2 wein cells that have the accurate 1.35 volts and put them in the meter.

Weins are the same spec as the PX625's that originally were use in the Gossen, and have a flat discharge curve holding their voltage. Yes, they have a shorter life span, but that can be lengthened by taking them out when not being used and taping over the reaction holes.

I'm not suggesting you use them permantly, but that's the cheapest way you are going to find a true battery to test your meter. Then you will know if you should fork over the WAD that Gossen wants for the factory convertor to use contemporary silver oxide batteries.

Frankly, of about 6 Gossens I have had using various batteries, when they were powered by the proper voltage, either 9 volt or PX625 or Wein Cell 1.35s...all of them were within on stop of each other, and within 1 stop of my Gossen digital Luna Pro, and within one stop of my Minolta Autometer IIIf.

 

[dmr]

Yes, they have a shorter life span, but that can be lengthened by taking them out when not being used and taping over the reaction holes.

Yes, much shorter life span! 🙁

I put one in my newly-acquired Gossen Super Pilot and it lasted less than a month! Last week I wanted to use it so I put in a new Wein cell and put the tape back over the holes when I was through with it. That was Sunday. It's now Friday and the battery check still shows about 3/4 of the way to the white mark. I'm wondering how much extra life that taping over the holes when not in use will really get me.

I am most definitely looking for other work-arounds for this.