Static Discharge on film in camera

David A. Goldfarb

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• Mar 12,

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One upside of a ruined negative is that it can make a useful post on Photrio. I couldn't turn up another thread on this topic, though I'm sure there must be examples buried in some thread with a title like "What's this stuff on my negs?"

This is about the clearest example I've seen of static discharge on the negative, occurring most likely in the camera. I'd have thought I was immune from this problem in our relatively humid subtropical climate, particularly when shooting right on the beach, but we've been having some unusually cool weather, and maybe it's reduced the humidity in the air.

It's between the last two frames, so it's unlikely to have happened before the film was loaded or to be the result of triboluminescence from the tape attaching the film to the backing paper, which is at the other end of the roll.

The camera is a medium format Noblex 150 that shoots a 60x120mm panoramic image, so presumably the static is from the rotating drum, which is a known issue with these cameras, just not a problem I've experienced before. The film is Adox CHS 100, developed in ABC pyro 1+1+1+12.

And, yeah, those people out there on the water are doing yoga on paddleboards. Last edited: Mar 12,

AgX

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Some films have special antistatic features. For instance current Agfa films. OP OP

David A. Goldfarb

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Some films have special antistatic features. For instance current Agfa films.

Good point. Kodak also makes an anti-static layer.

AgX

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There are different approaches to gain antistatic (or just reduce static...?) The Agfa approach to me seems the most effect, in theory.

Yes, we saw such static induced artefacts here at Apug, but rarely and never anything as comparing films in a test, only some remarks on handling after processing.
And Honolulu was a not a place I would have expected static artefact to appear...

The camera is a medium format Noblex 150, so presumably the static is from the rotating drum, which is a known issue with these cameras,

Interesting. Never heard that before
Is the drum from plastic?
(But it does not touch the film anyway, the films rest agains guides that make part of the body. Material?) Last edited: Mar 12,

AgX

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In the past static artefacts had been described by the industry in their collections of artefacts. But the one and only recent industry publication I remember referring to this issue is the Kodak guide on photography in arctic conditions.

guangong

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In the past static artefacts had been described by the industry in their collections of artefacts. But the one and only recent industry publication I remember referring to this issue is the Kodak guide on photography in arctic conditions.

That&#;s exactly what I was thinking. No cold winters in Hawaii. Static usually caused by advancing very cold film too fast so on bitterly cold days I always advance film very slowly.

Could Hawaiians be similar to Floridians? Some of the coldest winters I have experienced are the interiors of houses during summers in Florida.

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It is not only a matter of temperature, but of the supply of water too, thus at freezing and in a hot desert you may have same relative humidity.

Also, as David hinted at, it is a matter of speed of charging: the higher that is the more conductive surfaces must be.

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One upside of a ruined negative is that it can make a useful post on Photrio. I couldn't turn up another thread on this topic, though I'm sure there must be examples buried in some thread with a title like "What's this stuff on my negs?"

This is about the clearest example I've seen of static discharge on the negative, occurring most likely in the camera. I'd have thought I was immune from this problem in our relatively humid subtropical climate, particularly when shooting right on the beach, but we've been having some unusually cool weather, and maybe it's reduced the humidity in the air.

It's between the last two frames, so it's unlikely to have happened before the film was loaded or to be the result of triboluminescence from the tape attaching the film to the backing paper, which is at the other end of the roll.

The camera is a medium format Noblex 150 that shoots a 2.25x5" panoramic image, so presumably the static is from the rotating drum, which is a known issue with these cameras, just not an problem I've experienced before. The film is Adox CHS 100, developed in ABC pyro 1+1+1+12.

And, yeah, those people out there on the water are doing yoga on paddleboards.

the electrostatic discharge can happening while rewinding the film too fast.

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One does not rewind rollfilm.


(But with type 135 that is an issue. Though we never discussed that.)

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I recall there was a lot of chit-chat about this in the mid 60's and a little later and it appears is not the winding on causes the static but the rewinding back into the cassette. When you consider that back in the 60's I cannot remember one camera had power rewind, but press boys used to rewind frenetically to get a new cassette inserted. They were the ones who were complaining. Most newer AF cameras come equipped with them as standard. My F6 is always rewound manually simply because I like to leave a bit of film sticking out of the cassette, so the problem has not affected me. (F4 & F5 models also offer manual rewind).

Why it was decided that it was the rewind action that caused the problem was that it never seemed to happen with medium format where the film went simply from one spool to another. Oddly enough there were never any mention of this happening where C41 (or C22) or slide film was concerned. Only B&W was affected.

Whilst we do get cold dry weather here in UK, especially where live, again the problem has never caused me an alarm. Last edited: Mar 12,

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Interesting as the temperature and high humidity in Hawaii should prevent static. OP OP

David A. Goldfarb

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&#;Cold weather&#; by local standards means it can get down to 58 deg. F at night, but it&#;s at least in the mid 60&#;s by morning and probably above 70F at noon.

Indeed power rewind can be an issue with 35mm film, but this example is with 120 film, so there is no rewind, and the film advance is knob wind, so not particularly fast.

The Noblex 150 is a swing-lens camera like the Widelux. The film plane is semicircular, and there is a drum made of plastic and metal materials that spins the lens and shutter assembly to project the image through a slit that passes over the film. The drum takes a half revolution to get up to speed and then exposes the film while the lens faces the front of the camera. My guess is that the spinning drum is the source of the static.

You can read about Noblex cameras at http://www.noblexcanada.com/noblexproducts.htm

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I have only had the problem in cold weather, dry weather and weather that is cold and dry. The only solution that I know is to advance the film slowly. I do not know what to do for cameras that automatically advance the film, for example my Nikon N75 and Nikon F100. My Hasselblads are manual advance, hence I do not have experience with cameras with motor drives, but I can use the exercise of advancing the film manually.

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Yes, static 'spiders' are commonly reported on ZeroImage pinhole cameras, particularly affecting (peculiarly) ACROS 100.
And it's not dependent on any weather condition -- it has been found to occur just about all the time with just ACROS.
There is no and never has been an incidence of static affecting any film in my Pentax 67. OP OP

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Interesting that the solution seems to be to switch films, unless I want to carry a grounding rod along with my tripod with a wire running up to the tripod screw. Hammering the rod 8 feet into the earth before every shot could get a little cumbersome, eh? So I&#;ll save Adox for other uses, and take my stash of Agfa APX 100 out of the freezer for the Noblex. And when that runs out, I guess I&#;ll either go Tri-X or maybe FP4+. Ilford has a patent for an anti-static coating from . Anyone know for sure whether Ilford film has an anti-static coating?

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Give the inside of the camera a few wipes with Ilford's anti-static cloth. This soft orange wunderkind also works well for treating lightbox surfaces so that dust isn't picked up by negatives/slides or whatnot. OP OP

David A. Goldfarb

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Not a bad idea in any case.

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I'll throw in another country and see you two. I did have some high humidity static discharges between sheets of 4x5 film (TMax100) while bicycling in New Zealand for several months -- lots of rain, lots of bumpy roads, film in the bag in the boxes, but still got bounced around. No thunderboldts like you got, though...more blotchy, acne-like. Ruined a few good negs.

Can you ground the camera/tripod -- attach a wire to it and have the other end on the ground?

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In this thread alone I read more about static artefact incidents than I remember of all other Apug forums in the past.
Is this just lack of memory? OP OP

David A. Goldfarb

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Can you ground the camera/tripod -- attach a wire to it and have the other end on the ground?

Possible, but might be too much to worry about for what so far has been a pretty rare phenomenon. As long as there are films that I like that use antistatic coatings, I think that's the best option.

One thing I wonder about is that when I last had the camera overhauled, Noblex Canada replaced the roller that transfers the motion of the DC motor to the drum with one made out of a new material that should last longer than the original part, which tended to deteriorate over time and splatter decomposed rubber bits around the camera's drive train. Maybe this new material is more prone to static buildup. Even if it is, I'd rather have the more durable part and figure out another solution for the static issue, since the cameras are out of production, and repair services and parts will become harder to come by over time. Last edited: Mar 13,

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In this thread alone I read more about static artefact incidents than I remember of all other Apug forums in the past.
Is this just lack of memory?

Shocking!! This is just shocking!&#;

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Perhaps some anti-static spray on that part then... OP OP

David A. Goldfarb

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I&#;ll see if it happens again before opening it.

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Noblex Canada replaced the roller that transfers the motion of the DC motor to the drum with one made out of a new material that should last longer than the original part, which tended to deteriorate over time and splatter decomposed rubber bits around the camera's drive train. Maybe this new material is more prone to static buildup.

Could be. I don't know what the guts of the camera are like, perhaps it is acting in the manner of a small scale Van de Graaff generator? Metal parts can hold a charge for a while if there's no obvious way for it to bleed off. Presumably it could discharge to the film if they get close together.

If this is really a camera issue, the service center has probably been getting intermittent reports or questions; it may be worth touching base with them. I've chased down a number of static problems on film and it can seem a bit like black magic until you sort of learn how it works. You might play with some dummy film in the light, running through the camera and then see if the film attracts dust (if something else discharges to the film, then the film itself will be charged, at least for a short time). I think you'd be better off to touch base with the repair center first (don't ask for a conclusive answer, just whether or not they've been getting any calls asking about it). Best of luck.

Hi.

Just bought my first soldering iron, perf board, and ordered some electronics components. I'm raring to go! But then, some components came in bags that said I would destroy the components if I touched them. I kinda knew this in theory, but now I'm faced with it in practice.

A quick google told me -- as most of you know -- you have to ground yourself, prevent the components sliding, and wear cleanroom gloves. It looked like cleanroom gloves are made of "vinyl"; that is, of PVC.

So, two questions.

If I wear disposable "doctor exam" powderless PVC gloves, it that enough to prevent damage due to electrostatic discharge?

Clear food packaging and shampoo bottles are also made of PVC. I want to keep the finished circuit board dry. Could I box the circuit in a food-storage container made of that thick, slightly pliable, long-lasting plastic? I mean, could I use a sandwich box, with a hole drilled for Vin and Vout?

Thanks a lot for your patience with a total beginner.

nyoo said: A quick google told me -- as most of you know -- you have to ground yourself, prevent the components sliding, and wear cleanroom gloves. It looked like cleanroom gloves are made of "vinyl"; that is, of PVC.

If I wear disposable "doctor exam" powderless PVC gloves, it that enough to prevent damage due to electrostatic discharge?

If you're just working on standard IC circuits you generally don't need gloves. They're usually only used when working on critical, high reliability parts. "Doctor exam" gloves are likely not conductive and could actually generate the static electricity you're trying to prevent.

Clear food packaging and shampoo bottles are also made of PVC. I want to keep the finished circuit board dry. Could I box the circuit in a food-storage container made of that thick, slightly pliable, long-lasting plastic? I mean, could I use a sandwich box, with a hole drilled for Vin and Vout?

Standard plastics are generally bad since they can generate and hold static charges. If you need to store the circuits, the package needs to be conductive plastic. It's especially made for this purpose and is usually black or a reddish color plastic.

The main thing is to ground yourself to the work surface with a wriststrap. They sell wrist straps and conductive work mats designed for this. Always put the strap on and connect it to the mat before touching the circuit. If you transport the circuit, it's desirable to place the circuit in a conductive bag. If not, touch the surface you are placing the circuit on before you touch the circuit to the surface. This will equalize the boards static with the surface. The idea is to always have everything at the same potential so no static discharge can occur. It doesn't necessarily need to be earth ground, just that everything is at the same voltage.

nyoo said: But then, some components came in bags that said I would destroy the components if I touched them. I kinda knew this in theory, but now I'm faced with it in practice.

Sometimes components come shipped in static bags even though they are immune to ESD. I've had resistors delivered in ESD bags with the warning sticker sealing the bag. So it pays to know which parts are static sensitive and which are not. Most ICs made today are static sensitive because they are usually CMOS. It pays to read the datasheet.
In general, if you have a static mat and a wrist strap connected to ground you will be pretty safe. You don't need the gloves.
All that said, all I do at home is touch a grounded object once I'm sitting at my work bench to remove any charge built up from walking around. I don't use a mat or wrist strap. But I live in a relatively humid climate and your environment may be different (different socks, chair, carpet, humidity, etc). hi,
A couple of extra things you can do.

Get a polystyrene ceiling tile, about 12in square, cover it all round with aluminium kitchen foil, connect the foil to ground thru a 470K or 1MO resistor. [use sticky tape to hold the foil and ground wire in place]

You then place your ESD sensitive components on the foil, you can also push the pins of the component thru the foil into the tile.
So every time you pick up an ic, you automatically ground yourself.
If you push the pins thru the foil, it also holds them in place as you put the tile to one side.
When you are building a project you can group the components on the tile and keep them tidy, bit like a hedgehog.

Also wrap conductive foil around the soldering iron handle and ground it thru a 470K or 1M0 resistor,
every time you grab the iron you are grounded.

Do you follow.? Thank you all for your help.

If you could, please, your answers led to a few further questions.

For crutschow and dknguyen: what's the conductive plastic generally used to box small (3" x 4") circuits? Can I use electrician's common plastic junction boxes? Or dknguyen's small metal boxes, plugged with silicone at Vin/Vout to keep damp out, and grounded?

For mneary: I have a damp basement. Seems like a place with automatic grounding. Would a wooden table in the basement work, as a work bench?

For kchriste: I'm not trying anything fancy, for a first project. The components marked with the ESD warning are a couple of opamps (UA741, LM293), a couple of mosfets (IRF540A, HUF), a diode (1N), and a temperature sensor (LM235). Are these in your "bagged for ESD but really immune" category? I'm especially disappointed about the LM235 temperature sensors, because I want to place these at a distance from the actual circuit, between some rubber and wood. Any suggestions here?

To ericgibbs, Thanks. I'll make your foil pincushion. For the soldering iron, I guess the foil will be attached to a length of some 22-gauge copper wire? What's the resistor for?

Again, thanks all.

nyoo said: To ericgibbs, Thanks. I'll make your foil pincushion. For the soldering iron, I guess the foil will be attached to a length of some 22-gauge copper wire? What's the resistor for?

Again, thanks all.

hi,

Thats to limit any current passing to ground thru the resistor to a safe limt for your body..You MUST use a high value resistor.

Consider you accidentally touched a mains point, with your left while working on say, a mains power supply and you were holding the earthed soldering iron in your right hand... Goodnight nyoo....

It also acts to discharge any static that your body/clothing has built up, slooowly, so that you dont get a rapid discharge.

There have been a number of forum threads regarding SAFE earthing of your workbench. Look thru them.!!!

Does this answer your question, if in doubt regarding any electrical safety topic, ask the forum.

nyoo said: For crutschow and dknguyen: what's the conductive plastic generally used to box small (3" x 4") circuits? Can I use electrician's common plastic junction boxes? Or dknguyen's small metal boxes, plugged with silicone at Vin/Vout to keep damp out, and grounded?

For kchriste: I'm not trying anything fancy, for a first project. The components marked with the ESD warning are a couple of opamps (UA741, LM293), a couple of mosfets (IRF540A, HUF), a diode (1N), and a temperature sensor (LM235). Are these in your "bagged for ESD but really immune" category? I'm especially disappointed about the LM235 temperature sensors, because I want to place these at a distance from the actual circuit, between some rubber and wood. Any suggestions here?

The plastic electrician's boxes are likely not conductive. The boxes I referred to are especially built to store sensitive electronic parts. The metal boxes would work fine. As long as you're grounded when you pick them up, the boxes don't have to specifically grounded all the time. You also could put devices or circuits in a regular glass or plastic jar or box if the devices are in an ESD bag. In general, leave devices in their ESD bags until you use them.

Incidently, the wrist straps designed for grounding your body also have a high value resistance in them for safety. Never ground yourself without this resistor. Radio Shack and others sell such wrist straps.

Most semiconductors, and especially MOSFET devices, should be considered ESD sensitive and handled accordingly. There's not a problem placing the LM235 a long distance from the circuit as long as it's connected and the leads are insulated. The danger is when the leads are not connected or exposed and can come in contact with a static source. Thanks again, all.

To ericgibbs: Yes, I follow. I've now read some of the electro-tech-online threads on ESD, and also found me a couple of 470K resistors.

But 2-3 further questions I'm finding hard to ask, so please bear with me.

When my perfboard-based circuit is complete, it needs to be protected. For this project, which is a thermostat in an outdoor shed, it needs a slightly weather-proof box or container. The container could be a glass jar with the circuit glued to its side and a hole drilled in its lid. It could be a metal box you buy mints in, wrapped shut with electrician's tape, with the circuit raised up off the metal on polystyrene cubes. Or it could be some humidity-proof plastic container sold openly -- only I can't see it -- in every electronics parts shop.

In what could I safely house a circuit, away from ESD and moisture?

And what is such a container called, so I can find it in future?

And does the negative terminal of the power source act as a ground, for such a container?

Thanks.

nyoo said: When my perfboard-based circuit is complete, it needs to be protected. For this project, which is a thermostat in an outdoor shed, it needs a slightly weather-proof box or container. The container could be a glass jar with the circuit glued to its side and a hole drilled in its lid. It could be a metal box you buy mints in, wrapped shut with electrician's tape, with the circuit raised up off the metal on polystyrene cubes. Or it could be some humidity-proof plastic container sold openly -- only I can't see it -- in every electronics parts shop.

In what could I safely house a circuit, away from ESD and moisture?

And what is such a container called, so I can find it in future?

And does the negative terminal of the power source act as a ground, for such a container?.

It's the individual components that are particularly sensitive when the are not connected to anything and their leads are exposed. Once they're in the circuit, they are generally less sensitive since the connections tend to provide paths to grounds for any static charges. The main concern is any leads coming off the circuit board.

Power supply leads are usually not a problem since they normally have large filter capacitors to ground which absorb the static.

If you have signal leads coming off the board, it is good practice to add some small resistor in series with each lead and a small capacitor to ground (if it doesn't adversely affect circuit operation.) Even pF will absorb a lot of static discharge, but more capacitance is better.

If the circuit leads are reasonably protected than the container is not so critical. For example, I doubt that most standard electronic devices have a static dissipative housing. The boards inside are just isolated from the housing and the I/O's are protected so there's no problem.

Most electronc supply places, sell various types of electronic plastic or aluminum housings which should be fine for your circuit. (See **broken link removed** for example),

Normally you would have one of the power terminals going to ground (ground connection on the power plug, if available). That keeps everything near ground potential.

nyoo said: For kchriste: I'm not trying anything fancy, for a first project. The components marked with the ESD warning are a couple of opamps (UA741, LM293), a couple of mosfets (IRF540A, HUF), a diode (1N), and a temperature sensor (LM235). Are these in your "bagged for ESD but really immune" category?

Yes, they are all immune to ESD except the IRF540A & HUF MOSFETs. Junction devices such as diodes, NPN & PNP transistors, bipolar OpAmps & ICs are immune to ESD. ICs that use MOSFETs are vulnerable to ESD. Once you put the MOSFETs (Or CMOS ICs) in a typical circuit, you won't have to worry about ESD for them either.

dknguyen said: Who knows? they could have been state of the art 3-terminal, CMOS semiconductor resistors.

Na, it's just that the shipping dept only has those bags so they use them. Or maybe they don't train the warehouse people to distinguish which parts are vulnerable to ESD so they have a blanket policy of treating all parts as ESD sensitive. hi nyoo,
A sandwich box would be OK, use your solder iron, [with an old bit in] to make any holes you need for your inp/out wiring.

A useful moisture barrier which is overlooked is kitchen cling film.
Many people think that cling film clings, because of static electricity, this is incorrect.
The film is sprayed with a very light film of glue during the manufacturing process.

If you have a small pcb that you wish to protect from moisture,
wrap it it a few coils of cling film then using your girl friends hair dryer carefully heat the film.
Any wires to and from the pcb can be passed the thru edges of the film sheet and if required can be tied with lacing cord.

Before my peers throw their hands up in horror, I have used this method on marine and outdoor projects and it works.

Advantages are you can see any LED's thru the film and its easy to replace after any repair.