Gossen Lunasix 3 versus Gossen Lunasix F

Has anyone here successfully replaced the mercury batteries in the Lunasix 3
Is the calibration procedure difficult / awkward, or more to the point, does it require any special optical test gear.

I have a fully equipped shop for RF and audio.

I’ve used a Lunasix 3 with both Wein cells and silver oxide batteries in MR-9 adapters. With Wein cells I got the same readings as a Sekonic L358, with silver oxide/MR-9s it underexposed by 1 stop, but it was consistent throughout the range. Therefore with MR9s I just set the film speed to be half the actual speed and it meters “correctly” i.e. the same as a Sekonic L358.

If I was buying that type of meter again I think I’d get the Lunasix F - the Lunasix 3 is a bit fiddly in use.

Thanks mate.
I guess that the 9Volt model makes more sense nowadays. Been reading up on Velvia 50 and it seems not to be a very forgiving film stock.

I plan to use my Nikon F100 (glass covering from 12 to 200) and I’ve never compared its various metering modes to a dedicated light meter. Some experimenting with specific lenses ahead!
Will home develop (clip test) and maybe try C41 too.

In for a penny, in for a pound. lol

I think the whole way of working with the Lunasix F looks better - with the six 3 you have to read a number from a meter, then transfer that to a dial, then read the exposure, whereas with the six F you just need to get the needle in the middle and you can read the exposure correctly.

If you’re not too set on having an analogue light meter, and don’t need very low light level readings, then the Gossen Sixtomat is only a little more expensive, is newer and digital, so you’re less likely to have a calibration issue. It’s like a Sekonic L308, but seems to be cheaper (possibly it’s not as well known).

Even though I have fully embraced the digital world many years ago, I’m always gonna be an analog guy at heart.
shuush... don't tell anyone!

We’ll see...
maybe I’ll flip a coin. lol

A friend gave me a Lunasix3 many years ago and never used it because of the discontinued batteries. Now that I'm shooting film again, I've revisited this light meter and got it to give me a reading using Lithium LR44 batteries with this adapter

The only problem is that I had to do some additional mods to get it to work since the negative contact in the meter touch the positive edge of the battery short circuits whole thing. I've made a mask out of gaffer tape that covers the edge of the battery and the metal of the adapter (only necessary for the bottom battery). The check battery shows the needle in the red zone or just past it when I have fresh batteries in. The two LR44 batteries are 1.5V each so 3V total where as the PX625 batteries are 1.35V (2.7V total). I'm guessing this wont be an issue for use with negative film but might be a problem with unforgiving slide film.

Maybe one day i'll get a newer light meter where I don't have to faff about as much to get it to work but for now I'll just play around with this one.

You’re better off using SR44’s than LR44’s as the voltage curve is much flatter vs discharge time for silver oxide cells than for alkaline.

If you use zinc-air batteries then the voltage is closer to that of the mercury cells, they just don’t last as long as the alkaline or silver cells.

I find once the zinc batteries are opened, about 3 months is it

@aenoether

Here is an informative article…

The trouble with mercury batteries (and what to do).
By Daniel J. Schneider.
schneidan.com/2015/05/19/the-trouble-with-mercury-batteries-and-what-to-do/

I’ve heard (although not tried) that painting over three of the holes on a zinc air battery with clear nail varnish (leaving just one) makes them last longer (and doesn’t affect the voltage)

I use MR-9 Adapters (shop.criscam.com/products/mr-9-mercury-battery-adapter) in my Gossen Luna-Pro meters and Leicaflex SL and SL2 cameras. Just follow the simple calibration procedure in your Gossen's manual.

Zinc air batteries would be the best choice in terms of voltage matching but the one at the closest dimensions to the PX625/MR9 are not readily available where I live, neither are SR44, unless I buy them online. I try to avoid purchasing online because too often I've ended up with counterfeit batteries. LR44 batteries are ubiquitous, ie I can find them at any supermarket, dollar shop, newsagent etc... which is why I use them. I'll continue to look out for the Zn-air or SR44 and purchase them if I find them.

VARTA make exceptional batteries.

Here is their Silver Oxide Button Cells pdf, with all specifications.
www.varta-ag.com/fileadmin/varta/industry/downloads/products/silver-oxide/VA_Folder_Primary_Silver_Oxide_Button_Cell_02_2.pdf

To the best of my knowledge, these are not being counterfeited.

oh... I found an old U.S.S.R. light meter that belonged to my late mother, I think it's working okay. lol
She religiously only shot 35mm slide-film all through the 1950s - 1980s