Getting a Weston Master III meter up and running?

BHuij · Nov 25, 2021

I just inherited one of these and would love to be able to use it. Cosmetically and mechanically it seems to be in perfect condition. And while I do get needle movement both in high- and low-light modes, I suspect my selenium cell is shot, as even in low light mode, I couldn’t get the needle past about the one third mark when pointing it at a cloudless blue sky this afternoon. Light reading showed about 3.2.

My initial research indicates that it’s at least theoretically possible to solder in a cheap photovoltaic cell and variable Ohm resistor in place of the selenium cell, and then recalibrate against a reliable meter by changing resistance. Has anyone successfully done this? Or is there a good guide you could point me to? Or even a recommendation on a specific PV cell that would fit the meter?

I already have another meter I like and an app that works fine in a pinch. I’m also aware that these meters go on eBay for very little. But this specific one has sentimental value, and I would be really happy to get it working reliably again. Any help much appreciated.

BAC1967 · Nov 25, 2021

Sometimes you can “wake up” a cell that has been kept in the dark for a long time by placing it in bright light for a few days. Doesn’t always work but I have revived a few this way. If you are seeing needle movement that’s a good sign.

Helge · Nov 25, 2021

These are a Fata Morgana of a siren song. I’ve tried several. They are all dead or dying, unless you are EXTREMELY lucky to find one from a dead luddite who had the cell replaced right before the service to do so closed twenty years ago, of who bought one of the last made.

MartinCrabtree · Nov 26, 2021

I had mine reconditioned by George Milton of Quality Light Metric. Unfortunately I heard he's out of selenium cells. There is a guy in the UK that repairs them.....cannot recall his name.

BrianShaw · Nov 26, 2021

Put it on the shelf and adore it for its heirloom status. If you want to use a Weston, get a Weston V… it’s similar but has a locking needle and will be 29 years newer. They can be found for decent price.

Quality Light Metric ceased operation earlier this year with George Milton retiring. Ian Partridge is the name that couldn’t be recalled. He does not appear to work on meters that old. While his prices might be right… that’s a ridiculous amount of money considering the light meter alternatives.

https://ian-partridge.com/westonrepair.html

BHuij · Nov 26, 2021

So nobody here has tried replacing the cell on their own? I can find a lot of Master Vs on eBay, but nobody will specify in the description whether they work.

At any rate, I’ve got mine sitting on the shelf in the office now where it can get some indirect sunlight. We’ll see if that gets the cell running again after a week or so. This meter has all the hallmarks of being purchased and never used, more or less immediately stashed away in a closet for years and years. Knowing the late owner too, that checks out. I’d guess the cell is just oxidized, be flabbergasted if it’s actually exhausted.

The Master III used actual ASA, not Weston Ei numbers, right?

peter k. · Nov 26, 2021

BrianShaw said:
Quality Light Metric ceased operation earlier this year with George Milton retiring.

Gasp... sigh.. oh nooooooo ...

Nicholas Lindan · Nov 26, 2021

TTBOMK Se (selenium) photocells are no longer available. I imagine outfits that repair old meters have a box of NOS Se cells. Meters that used to use Se have been redesigned and now use Si (silicon) photocells.

Si and Se cells produce currents that are within an order of magnitude of each other. It is, theoretically, possible to replace a Se cell with a Si cell and re-calibrate the meter by adding a shunt resistor across the meter coil - this requires, of course, that the Si replacement produces more current than the Se original.

However, if the meter coil has a high resistance, and the system is designed for a cell with high internal resistance, then trouble will ensue when attempting to replace the Se cell with Si, as I found out.

I attempted to change out the shorted/defective/corroded Se cell in a Fed 5 with an amorphous Si cell. I gave up - trying to re-calibrate the system proved to be a great PITA. It could be done, it would need a new meter scale in addition to playing with shunt resistance. But I decided I just didn't like the camera enough to bother, better things to do with my time.

BrianShaw · Nov 26, 2021

BHuij said:
So nobody here has tried replacing the cell on their own? I can find a lot of Master Vs on eBay, but nobody will specify in the description whether they work.

Your search of the internet is the same as mine, and I've been searching for years; There are no really useful repair or remove/replace details available. If replacement or substitution of the cell had ever been made, as opposed to simply hypothesized in some random internet know-it-all's mind, it would be documented somewhere.

I revived a seemingly dead Master III once that was reading really low (like yours, it seems) by disassembling and cleaning up contacts. Disassembly and reassembly instructions are out there. YouTube, I seem to recall; or maybe on some web site; I can't really recall. It wasn't as easy as I thought but it was do-able. The meter worked fine for years, or so I thought.

Recently I started having troubles reading the dial so I bought a Master V and then a Gossen LunaPro SBC. My goal was for a locking meter needle and an easier to read calculator. The Master V gave me one of those; the LunaPro SBC gave me both but in a much bigger meter package. ALL meters on eBay seem to have the same lack of information, cover-my-@$$ seller disclaimers, and pictures in which one cannot determine if the meter actually sees light or not. It's a crap-shoot but with careful scrutiny I've not been disappointed yet. One has to be ready, willing, and able to execute a "not as advertised" return if necessary.

Now I have way too many light meters for my photographic need so decided to figure out which will get used and which are to be put into hibernation. Interestingly, all of my cameras with internal meters and external light meters agree within reason EXCEPT for the Weston III. It was actually 1 stop over. I used it for B&W only and never really noticed the error. But why 1 stop over and not the 1 stop under than one predict for an aging selenium cell?

awty · Nov 26, 2021

They have very fine bits and pieces, really need to know what your doing. I have a V dismantled in a snap lock bag after I managed to accidently damage a fine coil spring while trying to fix a dud cell and ended up just buying a working version.

Helge · Nov 26, 2021

IMO they are just not worth bothering with. They have an interesting history. Look reasonably good (wouldn't go so far as to call them beautiful or canonic design though). But the ergonomics suck and the reliability used is terrible.
Get a Sekonic L-398A, They are still made, are a pleasure to use and are serviceable.
You can very quickly spend double up on duds, instead of biting the bullet and just do the sensible thing once and for all.
A new Sekonic L-398A will last you 20 - 30 years.

BHuij · Nov 26, 2021

Well, if a couple of weeks of light and/or a decent cleaning of contacts doesn't get it up and running, then it's of no real use to me, sentimental value or no. I might just get adventurous and try to take it apart and swap out the selenium meter for a more modern photocell, and adjust accordingly with a variable resistor. If I end up attempting it and succeed, I'll be sure to document carefully

BrianShaw · Nov 26, 2021

… so it’s really not very sentimental… no problem.

Good luck!

BHuij · Nov 26, 2021

BrianShaw said:
… so it’s really not very sentimental… no problem.

Good luck!

Sentimental enough that I'd love to use it. Sentimental enough that it doesn't make any sense for me to go find some other Weston Master to use instead. Sentimental enough that it's worth trying to fix despite having a Spotmeter F. Not sentimental enough that I'd frame it and hang it on the wall if I can't get it working.

Helge · Nov 27, 2021

The main thing (and in my eyes the only thing) the Western has got going for it is the Invertycone.
Size of the diffusion cone shouldn’t matter, but sometimes it’s seems it actually does, and the unique shape could in theory make it less susceptible to get fooled by invisible local variances.
But the same thing can be done by moving a normal bubble cone around a bit and taking the average.

BrianShaw · Nov 27, 2021

The Invercone was a brilliant design (all 3 of them, although the last was bulkier than first two and flimsy build). I saw a paper where the patterns were mapped and they are indeed slightly different, flatter field, than the more common hemisphere. The last 2 designs (for Weston IV and V) were even a bit weighted along the axis of the meter so reduced sky influence if the meter is held correctly. Your observation and experience matches mine and seems based in the basic engineering of the Invercone. Potentially just a bit less error potential than the hemispheric domes.

r_a_feldman · Nov 28, 2021

BrianShaw said:
.I revived a seemingly dead Master III once that was reading really low (like yours, it seems) by disassembling and cleaning up contacts. Disassembly and reassembly instructions are out there. YouTube, I seem to recall; or maybe on some web site; I can't really recall. It wasn't as easy as I thought but it was do-able. The meter worked fine for years, or so I thought.

Same here — I gently cleaned the contacts between the photo cell and the rest of the meter. That worked for me.

When disassembling the meter, I used an aluminum tube as a wrench for the two recessed bolts holding the case together. I got a tube that was just smaller than the widest part of the bolt, bent the tube into a L (to get leverage), and forced the tube down over the bolt. The aluminum deformed enough to grip the bolt.

Pioneer · Nov 28, 2021

I bought a rebuilt Master III several years ago and I love it. It goes everywhere I go whenever I am using my Ikoflex. They make a great pair. I don't know if it is accurate enough for slide film, I've never tried, but it certainly works great for Ilford HP5+ and for Kodak Portra 400. That is all I need.

I use other options for my 35mm cameras.

BHuij · Nov 28, 2021

Pioneer said:
I bought a rebuilt Master III several years ago and I love it. It goes everywhere I go whenever I am using my Ikoflex. They make a great pair. I don't know if it is accurate enough for slide film, I've never tried, but it certainly works great for Ilford HP5+ and for Kodak Portra 400. That is all I need.

I use other options for my 35mm cameras.

When you say "rebuilt," do you know if the selenium cell was fixed or replaced with another selenium cell (or some other kind of cell?)

Mine has been sitting in moderate indirect sunlight for a few days now and it seemed like maybe it was working better last time I picked it up and pointed it around, but still not particularly accurate. I think this week I'll try taking it apart to clean the contacts and inspect the selenium cell.

Pioneer · Nov 28, 2021

The selenium cell had been replaced a couple of years before I bought it. It is still very accurate but it doesn't work really well in very low light.

Helge · Nov 28, 2021

Cleaning the contacts is far more difficult than you make it sound.
A. You have no idea of how good a job you did and why exactly it’s still not working properly.
B. There is a trillion extremely frail and brittle things to break inside there. And often stuff you only know about when you broke it.

I tried “cleaning the contacts” on several dead selenium meters, and it never worked.

btaylor · Nov 29, 2021

Helge makes a valid point. But I took a non functional Weston lll that I bought just for the case ($5), took it apart, cleaned the very delicate contacts and surprisingly brought it back to life. Inside that housing were extremely delicate bits I luckily did not damage. So if it’s just going to sit on a shelf anyway, why not try a repair?

BHuij · Nov 29, 2021

btaylor said:
if it’s just going to sit on a shelf anyway, why not try a repair?

Exactly my thought process. I've done work on cameras and leaf shutters and whatnot before. No, I'm not some kind of repair expert. But I'm plenty comfortable finding out how far I can get with a set of screwdrivers and a methodical, gentle approach to disassembly and cleaning. Worst case scenario I have a broken, useless meter worth $5 in several pieces instead of a broken, useless meter in one piece.

Interestingly, every guide I've seen says that the meter is held together by smooth headed screws with no obvious way to get purchase on them to unscrew them. Mine has two flathead screws on either side of the zero corrector. So either I got an anomaly, or someone else did work on this meter in the past and replaced or modified the factory screws.

These two screws come out easily, which allows the front plate to begin separating from the rest of the meter. However, something at the top of the meter appears to be holding the plate on so I can't get it the rest of the way off. I'll have to spend some time with it this evening and see if I can figure out what.

Sirius Glass · Nov 29, 2021

BHuij said:
Exactly my thought process. I've done work on cameras and leaf shutters and whatnot before. No, I'm not some kind of repair expert. But I'm plenty comfortable finding out how far I can get with a set of screwdrivers and a methodical, gentle approach to disassembly and cleaning. Worst case scenario I have a broken, useless meter worth $5 in several pieces instead of a broken, useless meter in one piece.

Interestingly, every guide I've seen says that the meter is held together by smooth headed screws with no obvious way to get purchase on them to unscrew them. Mine has two flathead screws on either side of the zero corrector. So either I got an anomaly, or someone else did work on this meter in the past and replaced or modified the factory screws.

These two screws come out easily, which allows the front plate to begin separating from the rest of the meter. However, something at the top of the meter appears to be holding the plate on so I can't get it the rest of the way off. I'll have to spend some time with it this evening and see if I can figure out what.

Why not have it repaired and calibrated at the same time? An uncalibrated light meter is useless dead weight.

BrianShaw · Nov 29, 2021

Sirius Glass said:
Why not have it repaired and calibrated at the same time? An uncalibrated light meter is useless dead weight.

Where?

Getting a Weston Master III meter up and running?

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