Extending the Useful Life of Our Film Cameras

Born2Late · Apr 23, 2019

Something that I have often pondered is the limited usable lifespan of our film cameras. Those of us with one or even many primarily mechanical cameras may have many years of life left in them. Perhaps the weakest part of them is their meters; to be more specific their CdS or selenium cells. Assuming manual exposure and aperture, we can use the "Sunny 16 rule" or handheld meters until the cameras become otherwise non repairable.

So, what I am wondering is, are there a practical ways to substitute components (and tune) to keep the meters functional. Could small solar cells replace selenium cells; could photo diodes be used to replace CdS cells? Could / would their response, spectral and illumination be close enough to function properly? All of this is above my technical expertise, but I am hopeful that somewhere within our members someone has the answers.

Any volunteers?

Chan Tran · Apr 23, 2019

You're talking about redesign the entire metering circuit and it's not very difficult but the difficult part is to put it in the camera. Even disassemble and reassemble a camera is difficult. I would much rather use these cameras without the meter.

Born2Late · Apr 23, 2019

Born2Late said:
Something that I have often pondered is the limited usable lifespan of our film cameras. Those of us with one or even many primarily mechanical cameras may have many years of life left in them. Perhaps the weakest part of them is their meters; to be more specific their CdS or selenium cells. Assuming manual exposure and aperture, we can use the "Sunny 16 rule" or handheld meters until the cameras become otherwise non repairable.

So, what I am wondering is, are there a practical ways to substitute components (and tune) to keep the meters functional. Could small solar cells replace selenium cells; could photo diodes be used to replace CdS cells? Could / would their response, spectral and illumination be close enough to function properly? All of this is above my technical expertise, but I am hopeful that somewhere within our members someone has the answers.

Any volunteers?

I was hoping some wizkid could come up with a grain of rice size micro processor based controller that would work with a modern sensor to make up a retrofit system. Oh yes, work on a silver oxide cell.

We can always hope.

KN4SMF · Apr 23, 2019

Born2Late said:
I was hoping some wizkid could come up with a grain of rice size micro processor based controller that would work with a modern sensor to make up a retrofit system. Oh yes, work on a silver oxide cell.

We can always hope.

I've thought about all this too. but alas, we live in a profit-based system. Just not enough money in it and too many different camera designs.

Theo Sulphate · Apr 23, 2019

Easiest and most cost-effective way to solve the dead meter issue (other than ignoring it or using a handheld meter), is to get the cell or electronics from a same model donor camera.

Selenium cells weaken over time and by exposure to light, so I cover mine when not in use. CdS cells don't have the same deficiency, I think.

pbromaghin · Apr 23, 2019

I hate to say it, but the most likely best solution to the dilemma will be smart phone light meter apps. I've come to the conclusion that I may outlive the electronics in my 35mm cameras, but all my medium format cameras (completely manual) will outlive me.

jim10219 · Apr 23, 2019

You could theoretically replace the selenium meter with a silicon solar cell. They provide a higher voltage, so you'd need to drop the voltage to make them work. They also don't have the same spectral sensitivity as selenium, which closely mimics film.

One way to do that would be to install a small resistor in series, precisely matched to mimic the selenium cell. Use a potentiometer in series to fine tune the resistance, and then replace it with a resistor of the determined amount that will easily fit into the camera. And even better method would be to use a zener dropping diode, but that would be more difficult to fine tune since they don't come in as many options as resistors.

Another method would be to place a filter over the silicon cell to fine tune both the amount of light and the spectral sensitivity. That might be more difficult to pull off on a small scale, as you'd likely have to dye your own filter because I doubt you'd fine a good candidate off the shelf.

The advantage of a CdS is they work much better in lower light. It would be possible to make a CdS metering circuit out of SMD components to mimic the voltage response of a selenium cell. Selenium cells are usually quite large and replacing them with a CdS or silicon wafer would reduce the size of the sensor and free up some space for the added components. But then there's the issue of the battery and where to place it, especially since it needs to be easily accessible.

I've thought about trying this with some of my old selenium cells, but I've found the ones I have actually still give accurate readings, so long as you halve the ISO setting.

jim10219 · Apr 23, 2019

Another thing to consider for extending the life of electronic cameras is to replace the electrolytic capacitors in their circuits. They tend to have short life spans (10-30 years on average) and when they go bad can not only cause the camera to act up, but can actually damage other circuit components which might be much more difficult to replace. So it would be smart to replace them with high quality ones before you notice problems.

It would also be wise to clean and lube any potentiometers, switches, buttons, or contacts, as well as any other moving parts. Motors and actuators can also wear out, and there's not much that can be done about them, other than pull one out of a donor camera (or get lucky and find a new, compatible replacement). But keeping the rest of the camera cleaned and lubed should keep them from wearing out too quickly by limiting the stress on them. Unless of course it's a later Pentax camera, like a ZX50, in which case the mirror motor is just a bad design and doomed to fail.

Also other electronic components can fail, of course. But they tend to be the much more robust with lifespans sometimes in the hundreds of years. So your moving parts and electrolytic capacitors are the most likely to fail, and the ones I'd concentrate on. Oh, and battery compartments. Leaky batteries have destroyed plenty of cameras, especially alkaline batteries. Vinegar or another mild acid (like most sodas) works well to clean up that mess. Just be sure to clean up the cleaner when you're done.

Theo Sulphate · Apr 24, 2019

jim10219 said:
Another thing to consider for extending the life of electronic cameras is to replace the electrolytic capacitors in their circuits. They tend to have short life spans (10-30 years on average) and when they go bad can not only cause the camera to act up, but can actually damage other circuit components which might be much more difficult to replace. So it would be smart to replace them with high quality ones before you notice problems.
...

Is it possible to specify an approximate date where use of electrolytic capacitors had not yet begun to occur?

For example, some cameras of the 1980's, such as the Canon AE-1 Program, are likely to have electrolytic capacitors, but would a 1976 Canon F-1n or a Nikon FM (whose only electronics are for the meter) use electrolytics?

Having a good "boundary date" would help identify which cameras are "safe" and which are candidates for an electronic component upgrade.

Jim Jones · Apr 24, 2019

electrolytic capacitors have been commonly used since probably the 1930s.

4season · Apr 24, 2019

The best way to make cameras and lenses last is to keep them scrupulously clean and store them properly.

KN4SMF · Apr 24, 2019

Capacitors are not used in ordinary simple CdS or selenium meter circuits. They would have a place in automatic cameras containing transistors or IC's. And I agree that swapping in fresh caps would be the thing to do, but it would also invariably entail recalibration, which most people have no means of doing or the factory paperwork to do.

jim10219 · Apr 24, 2019

And now that I think about it, it can't remember seeing one in a camera that wasn't there for the integrated flash. That doesn't mean that they would only be used for flashes. Just I don't currently remember seeing one in any of the cameras that I've worked on being used for anything other than to operate the flash. Then again, I'm not a professional camera repairman. I probably have only repaired around 30 cameras, and most of them were fully mechanical or just had simple metering circuits. The majority of my experience working with vintage electronics is in the audio, TV, and test equipment fields, with my primary electronics work involving photography gear having come from working on old flashes. And of the old flashes I've worked on, I'd say 80% or more had failed or failing electrolytic caps (ESR meters are great for this, by the way!). So maybe my experience has just skewed my perception towards paranoia.

So maybe an integrated flash would be a good way to tell if it had electrolytic caps inside? I don't know. I never thought enough to keep notes on these things, so it would probably be wise to ask a professional camera repair person this.

spark · Apr 24, 2019

There are separate circuits involved. Simple metering could be altered to use newer technologies, since the 1980’s silicon cells replaced CdS and selenium in light meters. (Adjusting the spectral sensitivity is another issue). If you want to go digital, microprocessors with <20 nm line widths run internally on 0.7 or 1.1 volts so a silver cell is not an issue for our slow clock speeds.
Flash circuits are the ones using big electrolytic capacitors, you may find that modern ones are smaller and more reliable than 1950’s-1980’s models. Lots of development there as they’re part of switching power supplies.
The big trouble is with dedicated LCD displays and computer microprocessors used in cameras. Fully electronic control cameras may have a short life compared to a mechanical camera (or you) since these dedicated parts have a very short production life.

jim10219 · Apr 24, 2019

spark said:
There are separate circuits involved. Simple metering could be altered to use newer technologies, since the 1980’s silicon cells replaced CdS and selenium in light meters. (Adjusting the spectral sensitivity is another issue). If you want to go digital, microprocessors with <20 nm line widths run internally on 0.7 or 1.1 volts so a silver cell is not an issue for our slow clock speeds.
Flash circuits are the ones using big electrolytic capacitors, you may find that modern ones are smaller and more reliable than 1950’s-1980’s models. Lots of development there as they’re part of switching power supplies.
The big trouble is with dedicated LCD displays and computer microprocessors used in cameras. Fully electronic control cameras may have a short life compared to a mechanical camera (or you) since these dedicated parts have a very short production life.

So long as those electrolytic capacitors are properly made, then yes, newer ones are more reliable than the older ones. However, there have been a couple of waves of what has been dubbed "capacitor plague". It's basically where manufacturers get sloppy with the chemical makeup of the electrolytic fluid which causes the cap to degrade in just a few years. Also, heat, excessive use, and non use can cause electrolytic caps to age prematurely. Japanese and American made caps seem to have avoided the "capacitor plague" waves, so I always use them in my builds.

Microprocessors are aged through excessive heat and voltage. In a camera, they aren't ran hard or often, so they still should outlast us on average (there are always outliers). However, being extremely proprietary parts (and hard to desolder, might I add) they can be difficult to find a replacement for if they do go bad. You'd likely have to remove one from a donor camera without destroying it, and install it into your camera without ruining the delicate traces. It's probably better to just replace the camera in this case.

LCD's are a real problem however. Some are better built than others. But they don't like heat, can corrode at the contacts, and be demaged by impacts. Sometimes modern replacements can be found, but more often than not, you'll need a donor camera.

But you're right. I have some shutters over 100 years old that still work as good as new. I doubt most electronic cameras will still be fully functional in 100 years.

John51 · Apr 27, 2019

With todays emulsions, I don't think metering is needed much. I ran a roll of Kodak ColorPlus through my newly acquired Kodak Signet 35 that has an erratic shutter and didn't lose a frame. About 4 shots had washed out colours, that must have been some heavy over exposure. imo many would have paid a premium to have that latitude in the 70s.

The clockwork shutters dying is a worry. Maybe an engineering tutor could give their class clockwork shutter design as a project. Being able to fit a brand new shutter into an old camera would be great. Especially Kodak shutters.

Bill Burk · Apr 27, 2019

Capacitor is an important functional part of my Pentax ES-II which was around my neck - working fine today.

GRHazelton · Apr 27, 2019

KN4SMF said:
Capacitors are not used in ordinary simple CdS or selenium meter circuits. They would have a place in automatic cameras containing transistors or IC's. And I agree that swapping in fresh caps would be the thing to do, but it would also invariably entail recalibration, which most people have no means of doing or the factory paperwork to do.

You're right about electrolytic caps. I have two big old EICO basic amps, neither of which would I "fire up" without replacing the electrolytics. Fortunately they're both point to point wiring, so the job would be relatively simple. I enjoyed using them in college, after several hours the room was distinctly warmer - warm sound, too . Each drew 300 watts from the AC, according to the chassis data.

M Carter · Apr 29, 2019

Maybe no-brainer ideas, but...
Store leaf shutters un-cocked;
If you live in a humid environment, invest in a dry cabinet - check B&H, they're surprisingly affordable;
Anyone know how a small refrigerator would function for camera and lens storage? Keeping gear a bit below room temp and managing humidity (no idea how a small fridge deals with humidity);
Find a good leather treatment for bellows.

With camera repair masters dying off, it's sad that there isn't some way for their knowledge to be passed on - there are people who specialize in specific brands, but things like shutter repair and adjustment are beyond me.

Sirius Glass · Apr 29, 2019

M Carter said:
Maybe no-brainer ideas, but...
Store leaf shutters un-cocked;

Hasselblad lenses should be stored cocked according to the manufacturer and repairmen trained by them.

Marco Gilardetti · Apr 30, 2019

M Carter said:
Find a good leather treatment for bellows.

I discourage anyone to do that. Whichever greasy treatment is spread on leather is very prone to develop molds as soon as ambient humidity reaches 90%, which takes just a pair of rainy days. Non-greasy treatments do nothing to leather, they're just aesthetic. Bellows leather was factory pre-treated with the best technologies available back then and in my opinion there is nothing that would safely prolong its life and keep it functional at the same time.

Supposed that it's "leather" at all, because in many cases it looks to me just pressed cardboard.

crumbo · May 7, 2019

By far, most of the cameras we used to see for repair were "failing" not due to any sort of electronic malady, but disintegration of plastics and rubberized materials, such as the coatings on shutter curtain fabric, plastics holding parts in place such as battery chambers, meter housings, and the like, light-tight foams around covers (how well we know this one!), and rubber bumpers within mechanisms to reduce noise and vibrations. My theory is that heat and poor storage conditions contribute most to these failings.

Other than that, "modern" electrical cameras often fail due to tarnishing and corrosion in switches and contacts. My theory there is it's best to use them, and use them often, to keep those switches working and clean.

Extending the Useful Life of Our Film Cameras

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