Metering circuits that employ the Wheatstone Bridge design can get away with 'wrong Voltage' battery, but many meters do not use such a design. Best to find a thread that discusses your specific meter with 'wrong' battery.
PX-13, mercury cell. Might not be insensitive to voltage as Sekonic offered a voltage-reducing silver cell adapter, which works quite well in that meter. It was pricey and now out of production.
I don’t know about your part of the world, but where I live the mercury cells were banned decades ago due to environmental concerns. That’s why we stopped using and having access to them.
I don’t know about your part of the world, but where I live the mercury cells were banned decades ago due to environmental concerns. That’s why we stopped using and having access to them.
All Lunasix 3, Luna Pro, and Luna Pro S meters were made to use 1.3v Mercury batteries. Near the end of production of the Luna Pro S, the last version of this meter made, they included a battery adapter that lowered the voltage of 1.55v silver oxide batteries to match the voltage of the Mercury cells the meter was calibrated for. This adapter was also sold separately so people with the older meters could buy the adapter and use it on their meters. The meters that came with the adapter were marked "1.55v Silver Oxide" on the bottom plate; but it is important to know that this applies ONLY if the meter still has the adapter. If a previous owner lost it or kept it, the meter still requires the 1.3v mercury cells!
I've seen two 'Luna Pro S' meters (same as Lunasix 3) that used 1.5v batteries. Actually, one of those may have been a regular Luna Pro -- I'm not sure of my recollection on that. They were black but I have also seen many of them that are black that use the mercury cells so you can't go by color. The only way I know to tell is to look at the printing under the battery cover on the back. Gossen evidently made very few of the 1.5v versions. I say that because I have spent quite a bit of time looking for one. Maybe they're easier to find in Europe?
YouTuber "Fix Old Cameras" has a video on converting a Luna Pro to use 1.5v cells via diode installation if you are comfortable with disassembly, soldering and reassembly.
Another solution is to get one of the Luna Pro models that use 9v batteries. I recently found a Luna Pro F in mint condition that works perfectly. It's a bit large, however. I think the Luna Pro SBC (also 9v) might be a little smaller.
All Lunasix 3, Luna Pro, and Luna Pro S meters were made to use 1.3v Mercury batteries. Near the end of production of the Luna Pro S, the last version of this meter made, they included a battery adapter that lowered the voltage of 1.55v silver oxide batteries to match the voltage of the Mercury cells the meter was calibrated for. This adapter was also sold separately so people with the older meters could buy the adapter and use it on their meters. The meters that came with the adapter were marked "1.55v Silver Oxide" on the bottom plate; but it is important to know that this applies ONLY if the meter still has the adapter. If a previous owner lost it or kept it, the meter still requires the 1.3v mercury cells!
Makes sense.
… and then there is this, which may be adding to the (my) confusion:
That is the most succinct and precise explanation of the history I’ve come about. Thank you! Explains a lot of the confusion.
I have quite a few of vintage Gossen in various states. The F with 9V and flash measurement is fine, but it doesn’t go that low, they are big and they are somewhat unreliable IMHE.
The unreliability is also a problem with the Pro SBC. And again it’s the same size.
I’d love a good copy of that though.
The Lunasix/Pro line of CdS meters are super simple, rugged and go incredible low considering their age. Lower than many modern meters and lower than the F.
And they look damn good.
The Luna Pro SBC looks just like your Luna Pro F and also uses the 9v battery. The SBC does not meter flash, but has the same low-light capability as the older CdS Luna Pro meters.
The Luna Pro SBC looks just like your Luna Pro F and also uses the 9v battery. The SBC does not meter flash, but has the same low-light capability as the older CdS Luna Pro meters.
Actually, the Luna Pro is more sensitive than the SBC in low light.
- Luna Pro -8 LV
- SBC -5 LV
- Lunasix 3 -4LV
- Luna Pro F -1 LV
That's not true. The Luna Pro only goes to EV -4 at ISO 100, same as the SBC.
Recalibrate with silveroxide batteries is my recommandation.
Recalibrating seems like a nightmare. It requires closing the case each time, perfect light and worst of all you bring the pots and cell into extremes where they are most likely less linear.
Either I’ll try my hand at installing a diode, or I’ll bite the bullet and buy two more adapters.
Several people here have mentioned good success with the very affordable voltage-reducing adapters sold on ebay by someone in Thailand. I bought from CrisCam and paid more but just as satified.
Bite the bullet. Having thought about modifying and destroying one meter trying (getting it appart was a lot more difficult than I imagined), so bought the corrrect adapter and never looked back. Several people here have mentioned good success with the very affordable voltage-reducing adapters sold on ebay by someone in Thailand. I bought from CrisCam and paid more but just as satified.
Do you have a link to those? Can’t even find a mention of them.
That would be a game changer for everyone.
Having to put down close to $150 just to permanently load a couple of cameras with batteries and a Lunasix 3, is a bit ridiculous.
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