5 Levels of Shutter Testing: How Accurate is your Film Camera?

5 Levels of Shutter Testing: How Accurate is your Film Camera?

Introduction

Here at Kamerastore, we buy and sell thousands of cameras every year. With this experience, we know that the vast majority (over 80%) have some kind of issue that requires attention from our mechanics.

If you buy a camera online from someone who only does basic testing, or no testing at all, it likely will not work 100%. It could over or underexpose, have uneven shutter timings, a messed up light meter, or broken parts inside.

Getting a messed up roll back can be enough to dissuade someone from continuing with film photography. Even if the gear is to blame, the photographer might blame themselves and give up.

We're here to help explain how testing works so that fewer people get a bad start in film photography. Learning these testing techniques, and knowing the limitations of most stores in testing their equipment, will only become more valuable. These issues will get worse as cameras get older. So let's talk about testing!

A malfunctioning focal plane shutter can completely ruin your pictures – notice the uneven exposure on the left. This was a Leica M2.

We give all items condition ratings. Although most items we sell are working perfectly, any small issues that we can't or haven't fixed will be noted.

For example, many mechanical cameras will have issues with their top speed timings being off. If you buy from us, this comes with a slightly lower price and the peace of mind that the camera has been tested. You can use it knowing that the fastest speed is off, and compensate accordingly.

Different Levels of Testing

We use the most stringent testing requirements in the world, doing multi-point inspections and double-checking our results on state-of-the-art machinery.

Obviously, not everyone has access to the equipment, time, and knowledge necessary to test like we do. The equipment is heavy, rare, and expensive. So here we'll go through a few different levels of testing, as well as their pros and cons.

Testing is the only way to know if a camera is working properly or not. A "film test" does not tell us all we need to know, and sellers who use film tests to prove their cameras work are admitting that they do not possess proper testing equipment.

These 5 levels do not represent our condition ratings. Click here to get more info on how our rating system works!

Level 1: The Flea Market Test

Ah, the mysterious flea market. According to YouTubers, they're the only place to find cameras for "reasonable prices". But most flea markets don't test cameras, do they?

The answer is of course not. So you have to do it yourself!

A flea market level test can reveal basic problems about a camera. You can check if buttons press and levers pull, as well as checking for physical damage to the body, viewfinder, mirror, or shutter curtains.

Most cameras won't fire without batteries, so carrying a few types of batteries can be helpful. We recommend bringing around a Camera Rescue Film Case so you won't lose your batteries.

With the right battery inside, the shutter might fire and the light meter might react. If it does, you can test the slowest shutter speeds. These tend to get sticky, after all.

Unfortunately, this is not a way to test if a camera's shutter is actually accurate. Most people have a hard time telling the difference between 0.8 and 1.4s even though that's an entire stop of exposure different.

After slow speeds, try the fastest speeds. You won't be able to tell how fast the speeds actually are, but you should be able to tell relatively. 1/1000s should be faster than 1/500s, which should be faster than 1/250s.

Again, this tells you very little about the actual speed and accuracy of a camera's shutter. All it tells us is that the shutter speeds do change and that the camera isn't entirely broken.

Hopefully, this all sounds quite vague and inaccurate to you. We hope you wouldn't buy a camera from a store that "tests" their cameras in this way. Unfortunately, this is exactly how most online sellers check their cameras.

They run a camera through these very basic, unprofessional steps and then market a camera as fully working. The truth is that this level of testing only tells us if a camera is completely broken.

With this method, we know nothing about the accuracy of the shutter, light meter, or auto exposure modes found on cameras like the ever-popular Canon AE-1.

Level 2: Acoustic Check with a Phone

The next level of testing would be using acoustics to check basic shutter speed timings. This level of testing should be done on top of everything from step 1.

Basically, you use an app that records sound and shows you a graph of the sound's volume. In some situations, this can be used to see the distance between a shutter opening and closing.

This isn't very precise because you have to manually read the graph and there are other sources of noise in a camera besides the shutter. Naturally, an SLR mirror slap will throw off this test. You'll get best results with a central leaf shutter, a camera without a mirror, or an SLR with mirror lock up.

Here's an example of some sound samples taken with a Rolleiflex 2.8F that has been serviced by our master mechanics. The testing was done on the same day as the service, and our mechanics calibrated it using professional and period-appropriate techniques and tools.

 
At 1/2s it’s easy to see the peaks and identify when the shutter is opening/closing.
 
At 1/60s it's a bit harder to find the peak, but still doable.
 
At 1/250s we're basically just guessing. Even though a TLR with a leaf shutter should be easy to read, there are no audio cues that can help us.

As you can see, faster speeds will be impossible to accurately test with this method. Even with the relatively noise-less leaf shutters of a TLR, these tools are not sensitive enough. Focal plane shutters, which are vastly more common (especially in 35mm SLRs), will be even less accurate.

Focal plane shutters on fast speeds are constantly moving. This means they will always be making noise and giving us no useful audio cues. To change exposure times, the distance between the two curtains is changed. A wider slit lets more light in than a narrower one.

As we mentioned before, SLR cameras will also mess up this test with their mirrors. When you fire the shutter of an SLR, the mirror slaps up before the shutter opens, then slaps down once the shutter closes. With faster shutter speeds, this can seem to happen in an instant.

This level of testing offers more specificity than level 1, but not enough to actually know if a camera is working properly or not. While you can see the slower speeds quite well, most fast speeds will be unusable with this method.

As a seller, it would be dishonest to market a camera as fully working with this level of testing. As a buyer, know what you're getting into when you buy a used camera.

Finally, this test is not measuring actual exposure. While this can measure the time a shutter is open, it does not measure the light meter or automatic exposure. If you're using a popular camera like the Canon AE-1, this level of testing is not enough.

Level 3: 1-Probe Shutter Test

As with before, this level should be done on top of the basic level 1 testing. This technique can replace the acoustic testing from level 2, though.

A 1-probe testing machine captures light through a sensor on the film plane. This sensor can measure exposure times and shutter speeds. It only checks the timings, though, so it can't measure overall exposure, light meters, and auto-exposure.

Professional shops will have these machines for testing central leaf shutters, like those found on many medium format cameras. Modular SLRs like Hasselblads, TLRs like Rolleiflexes, and many others generally have a shutter like this.

This won't work as well for focal plane shutters because it only measures the time when light is reaching the sensor. Because focal plane shutters have two curtains, it's possible for the second curtain to overlap the first one at the end of the exposure. This very common issue normally happens with the fastest shutter speed and will get worse over time.

A machine like this would not be able to tell if this was happening.

Nowadays there are 1-probe sensors you can buy and plug into your phone. There are also newly-designed independent shutter testers on the market. While this is an exciting development, recent tests against professional equipment show that these newer sensors are not very accurate.

That being said, these sensors are still a significant step above acoustic testing and are capable of testing many types of cameras. Importantly, they're able to take readings of fast speeds.

Again, though, they're only capable of reading shutter timings. This means overall exposure, light meter accuracy, and auto-exposure are impossible to test.

Level 4: 3-Probe Shutter Test

This level of testing will allow you to properly measuring the timings of focal plane shutters, like those found in most 35mm SLRs.

Focal plane shutters need both curtains to be in sync. There needs to be 2, or even 3, light sensors in order to properly measure if the curtains are running at the correct speeds. This is to make sure that the slit between the curtains stays the same size throughout the exposure.

These setups must have multiple probes at a known distance from each other in order to properly measure exposure. They should also be able to work both vertically and horizontally, since focal plane shutters can be both vertical and horizontal.

With a machine like this, speeds can be tested for any camera with manual shutter speeds. This is the highest level of testing available for cameras with no light meters or auto exposure.

These days there is one multi-probe tester still made. It's hand-held and suffers from the same loose tolerances and inaccurate readings as the ones we mentioned earlier. It does not work as well as the old machines that we use.

Our old machines (pictured above) have probes that fit snugly into the area where film would be inside a camera. They're specially-designed to fit film chambers so that measurements are always taken from the same place inside a camera.

Because the old machines are rare, expensive, heavy, and need to be calibrated, very few stores actually use them. All focal plane shutter cameras sold on Kamerastore.com are tested with this equipment. It is the only way to properly test shutters.

Without this testing, selling a camera as "fully working" is misleading.

Level 5: Automatic Exposure Test

This is the most stringent level of testing and what we use for all auto-exposure cameras.

The challenge is to trick the camera into thinking it's reading light from a scene, like you'd do when you actually take a photo. These machines recreate different light levels at known values to see if the camera responds appropriately.

This is not easy. The light must be constant, flat, and exactly correlated to a known value. Our machines, and most photographic ones, use Exposure Values (EV) as the known value.

You can see on the machine below that there's a large dial for changing Light Values (LV), which are the same as EVs. By testing different intensities of light you can see if the camera reads all levels of exposure well, and test that the camera chooses that correct shutter speed and aperture where necessary.

For this test, though, you need a lens with a calibrated aperture. Because the camera is reading the light, we need to be sure that f5.6 is actually f5.6. We have calibrated lenses for every major system, ensuring that our exposure calculation is as accurate as possible.

Even if you have this high-end machine, your results can be inaccurate if you use an uncalibrated lens. It's also essential that focus is set to infinity for these tests. As with before, the probe must also be held in the same spot to ensure accuracy. Also like before, our probes are designed to fit snugly into the film chamber to eliminate discrepancy.

Some auto-exposure testing machines can also double as shutter timing machines, but it all has to be tested manually. Even if a camera has accurate shutter speeds, the light meter can still be off. And vice versa, even if a camera has an accurate light meter, the shutter speeds can still be off. Both must be tested.

As you can see, this work requires extremely specialized equipment and knowledgeable technicians. In the film era this knowledge and equipment was pretty well dispersed, but many of them were thrown away or destroyed. When digital took over, many people didn't see the need for them anymore.

The result is that far too few camera shops have this equipment anymore, and modern alternatives do not exist. It is impossible to properly test 35mm film cameras without this equipment, though. We are looking into ways to get accurate testing equipment into the hands of professionals around the world, so keep your eyes open!

Conclusion

Hopefully this article has helped you understand the challenges and requirements for proper film camera testing. Despite the difficulty and time required, this is not something we reserve for high-end gear like Leica and Hasselblads, though.

All cameras that pass through Kamerastore.com have been tested with these methods.

If a camera works properly we clean it, give it new light seals, and sell them. If it doesn't, we either repair it or sell it with the issues clearly marked. We do this to make the buying experience as easy and worry-free as possible.

The buying experience isn't the only reason to do this, though. The fact is that if we want cameras to last another 10, 20, 40, or 80 years we have to take caer of them. Many private sellers don't have the equipment or knowledge to test their cameras the way we do, so we have to work extra hard to test as many cameras as possible.

Of course, this comes with a cost. Our team is large and requires in-depth training to use these machines properly, and our process is longer than other stores because it takes awhile for each camera to be tested. We think the peace of mind and higher standards more than justify this price increase, though.

All cameras sold by Kamerastore are tested using the methods described above so we can provide a simple, easy, respectful buying process and give you as much information about your camera as possible.

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This article was originally published on 28.8.2020 by Arild Edvard BĂĄsmo and updated on 24.1.2022 by Connor Brustofski.

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