Build a shutter tester for Focal Plane shutters - Cheap, Easy & it Works

[Niglyn]

I may have got something wrong in my build, but the sensors in mine are on the distant side of their PCBs, which makes it difficult to get them close to the mask with its drilled holes. I suppose one could bend them in a loop around the end of the PCB so that they look the other way?

Hi,
I would bend the sensor legs backwards, so the sensor is now in line with the module, rather than sticking up at 90 degrees.

Add a bit of hot-glue to the legs where they plug into the module, to stop them coming out.

After attaching the wires to the module, the sensor can be hot-glued over the mask-hole and the module hot-glued to the mask, to stop it putting strain on the sensor.

There are many alternates. For example, solder a surface-mount 10k resister between Vcc and out on the sensor, and add a 0.1uf capacitor between Vcc & gnd legs. (or use a standard 1/4w resister).

This then makes a complete sensor module, but without the module. Or, use veroboard as I suggested earlier, which is also used as the mask.

These ideas do of course require a bit of electronic knowledge & soldering skills.

Using modules, especially if using five, will become a bit messy, however, the alternat is to go down the route of making bespoke pcb's which could become to difficult for many.

 

[ic-racer]

Just pointing out that a PCB with 3 sensors arranged for both vertical and horizontal from the "Film Camera Tester" project will work with this project too. The PC board comes drilled already with the holes spaced correctly as a drilling template for the front cover. The 3D printing files for its enclosure are also available:

film_camera_tester/assets/pcb/sensor_1 at master · srozum/film_camera_tester

DIY Film Camera Tester. Contribute to srozum/film_camera_tester development by creating an account on GitHub.

github.com

 

[Niglyn]

Hi IC,

Yes, it will (with a slight mod to my code). I assume the Lasers are placed at 20mm vertical and 32mm horizontal?
It removes the need for the two additional lasers & simplifies wiring.

Thanks for posting the pcb details. I could not really start suggesting peeps take parts from other projects )

'Genuine' sensors are available from Farnell, £1.24 each and a minimum order of £20. I still cannot find a source for the chinese knock-off ones, other than buying the whole sensor module.

I was also thinking of adding a light meter, taken from my 'build an exposure meter...cheap...' thread. It is so easy to do, using a modern all in one light sensor module that spits out light level in lux, & then a quick calc to give EV. Accuracy is rated at 20%, but they can be calibrated by writing back to the module. User can provide their own light source & wire it to a dimmer, compare the shutter tester reading to their own camera.

It does open the whole debate about what is EV and K value. Selenium cells & photo-diodes were around long before LED panels & the like & probably do not care. I found my film cameras under-read, this maybe due to film cameras exposing for the shadows & EV being subjective.

My over-complex nikon camera requires various pots set for different EV levels, so being able to have a light at 15EV, then 3 stops lower to adjust the next pot (as per the manual) would be most useful.

 

[ic-racer]

. I could not really start suggesting peeps take parts from other projects )

The creator of that project has indicated on his Github wiki the mechanical components are all open source to be used with any code.

[Film Camera Tester] is an open hardware project with a free firmware. Source code provided as an example or a template if you'd like to write your own tester with different interface or routines. I want you to understand that main value is an optic-mechanical design of a probes and light unit.

Hardware used in a project was chosen with careful considerations. All components are available for many years now and still will be obtainable many years later.
Similar projects that helped me to start my own

• https://github.com/cameradactyl/Shutter-Timer
• https://github.com/ianonahillroad/CameraShutterTimer
• https://github.com/c-s-1/shutter-tester
• https://github.com/sokol07/LaserShutterTester

---Serhiy Rozum

 

[Niglyn]

A quick photo of the tft display.

Full details are in a smaller typeface.

Larger display at the bottom shows shutter 'speeds', deviation from centre and curtain travel.
Colours change, green, yellow, red depending on how far from ideal the results are.

 

[Niglyn]

Firmware Update.

esp32 Version 3_0_8 now has flash timing.

Connect to the Pc sync socket or hot-shoe & it can be seen when the flash fires during the shutter cycle.

Additional error info shows if flash is firing before curtains are fully open after curtains start to close, or (shortly) after curtains are fully closed.

Just need to update schematic & destructions & it will be up on github

Can't think of anything else to add?

Next project formulating in my head is an automated twiddler for the Patterson development tanks.
Not sure how many people would find this useful?

Last films I developed, I twiddled rather than agitated & found it easier. The results seemed to have better contrast & there was no water splashed about from the waer-bath.

Being automatic, the tank would stir itself at the correct time based on:-
Total dev time,
initial agitation length,
total agitations
agitation length

Add audible warning when near end of cycle.
Stop time & twiddle for fixer could be added.

Steeper & driver £12
ESP32 & BO board, £6
tft £10

 

[Twotone]

Hi folks,

An update is certainly in order!

I've wrestled with how I was going to get lasers/receivers aligned in different boxes etc for a while and I did find it quite difficult.

Following some suggestions ref. Positioning of the sensors/lasers in a diagonal format, I did so, and removed the two vertical lasers/sensors from the equation.

I'm currently running the original code and 3 lasers/sensors.

Initial thoughts are that I'm impressed! I'm having an issue with alignment of the the camera to not block the laser beams, this I imagine is down to the positioning of the lasers not being perfect, something I'll look into again.

In addition, each time I'm winding the shutter on my test subject Zenit, it naturally moves the camera.

I need to brush up on my theory around curtain timing etc, but my initial thoughts are positive!

I'm going to probably take the approach of using the sensor holder from the professional build as suggested, along with a PCB, and then adjust the laser path to try and get some easier calibration.

As a separate bit of news I've seen Reveni Labs are building a shutter tester that is launching soon, which I'll probably be buying as a matter of course, but I'm still interested in building this out further, and would be a good test to see how this compares! https://www.reveni-labs.com/reveni-labs-camera-tester

Anyway, here are some pics! It's probably a bit more bodgy than I'd like, but that's what happen when it comes to me doing any precision drilling/measuring + a glue gun.

Definitely not a finished product.

PXL-20231014-172229204-MP hosted at ImgBB

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PXL-20231014-172243022-MP hosted at ImgBB

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PXL-20231014-170437946-MP hosted at ImgBB

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Thanks!

 

[Twotone]

Just as a quick follow up, I thought I'd try one of my fully auto EOS film cameras as it removed the need for me to wind between shots, allowing me to maintain the position of the camera.
The accuracy of the EOS is very good according to the tester which is reassuring! It did however start throwing showing some slower readings at the higher speeds which is both expected and probably confirmation that my positioning/masking drilling might not be perfect. (I'm talking about 1/12XX vs a desired speed of 1/1500.

Either way, whether the above sounds right or not, I'm going to look into changing out the 'sensor' box for one as suggested by IC-Racer, whilst considering how I can keep the camera in a position that does not require constantly realignment to work properly.

 

[chuckroast]

I too am an electronics designer and builder and I applaud your doing this for your own amazement.

However, I would be remiss if I didn't point out that this degree of accuracy and resolution is simply unnecessary for practical shutter use.

Older shutters for film cameras are routinely over 1 f/stop slow at the highest speeds but they are consistently so. So, one need only consider that when setting the exposure. Moreover, film is very tolerant of overexposure, which is what slow shutters (almost always the problem) will give you, if you use them at nominal rating.

Even if you can measure shutter timing to .000001%, it makes little difference unless you also have the ability to recalibrate the shutters that are out of spec. When/if you do, you'll discover that there is some variability shot to shot, and you cannot get older mechanical shutters to be perfectly spot on. For example, with the older Ilex/Acme shutters on LF lenses, you can get either good high speeds or good low speeds, but not both. This was true when they were new.

For digital, the situation is much better. Modern shutters in digital cameras are electronically timed and generally very accurate over the lifetime of the camera body.

 

[ic-racer]

Your tester certainly needs better tolerance than that allowed by ISO for the shutter. If the shutter can be 1/3 stop off and the tester is 1/3 stop off, you really can't tell much.

 

[Niglyn]

Hi TwoTone,

Thanks for the update on your build.

Putting all three sensors diagonally does allow for horizontal or vertical testing, but does make alignment a little more tricky than if they are all horizontal or vertical.

I made mine to be cheap and easy to build, thus using standard laser & receiver modules, without the need for 3d printed parts or bespoke pcbs. I'm more than happy for people to make these or add pretty boxes, adapt or change to their taste. I'm also more than happy for feedback, ideas & suggestions for improvements & additions.

There is no reason why a large light source could not be used, in place of the lasers, with the rx sensors positioned in the film gate.
I can trigger mine with white card reflecting from the computer monitor. Actually, that gives me an idea )

Mine will work with either the lasers or sensors in the film gate, although most people did not like the idea of lasers pointing into their camera.

The other reason not to use a large light source, other than adding complexity is that I did not want people electrocuting themselves.

Adding a light-meter to the shutter tester is very easy. I already have all the code from my exposure meter project. A reading in lux & EV can be displayed. The light meter sensor has a rated un-calibrated accuracy of 20%. Calibration is easy, the sensor allows for this within firmware, but one would need a calibrated light source to compare.

Control of the light could simply be a dimmer switch, available in any hardware store (of the correct type for the light, tungsten, LED etc) or adding pwm control from the shutter tester, but this again adds complexity & the risk of electric shock.

The Reveni tester looks interesting, but I cannot see it being any more accurate than mine. It is doing the same thing, measuring how long the light is seen for. The trick is to have very tight code to capture the timings with minimal latency.

I'm not an expert on leaf shutters, so cannot see how a computed shutter speed can be achieved with just one sensor (or else we could use just one sensor for focal plane shutters?) Mine will measure the raw speed of a leaf shutter, but then there will be some error due to the much discussed width of the sensor. If anybody has any ideas, please let me know & I can change the leaf shutter/single laser code.

As Chuckroast says, one should not be troubled by absolute accuracy. Old spring driven cameras will vary shot to shot, be affected by temperature etc. Consistency is more important. Film has a wide exposure latitude (not so much reversal, but who uses that?) and compensating developers & auto printing labs also play their part.

 

[snusmumriken]

I can trigger mine with white card reflecting from the computer monitor. Actually, that gives me an idea

Could one use the refresh rate of a computer screen to create something akin to the original (mechanical) Leica shutter speed tester? Refresh travels downwards, shutter travels across, result is a diagonal image of characteristic slope and width.

I tried this with a mini OLED screen and an Arduino, but refresh rate was nowhere near fast enough.

 

[OAPOli]

I'm not an expert on leaf shutters, so cannot see how a computed shutter speed can be achieved with just one sensor (or else we could use just one sensor for focal plane shutters?) Mine will measure the raw speed of a leaf shutter, but then there will be some error due to the much discussed width of the sensor. If anybody has any ideas, please let me know & I can change the leaf shutter/single laser code.

For leaf shutters, total exposure time will depend on the aperture. If you measure at the centre (small aperture value), total exposure is the time for opening + time opened + time for closing. Whereas if you measure at the edge of the shutter (large aperture), total exposure is just time opened. So if time for opening or closing is 1ms and time opened is 1/500 then there is a full stop difference between wide open and stopped down. 1/2 stop at 1/250 and so on...

I think nominal speeds are measured at the edge. In principle with two sensors you can measure closing/opening times. But measuring mid-way should be good enough for the faster speeds.

Edit: Actually I think that the total exposure time wide open can be computed via some sort of geometric integration? I.e when the shutter is half-open it contributes half the exposure during blade transit. That's why bokeh can get strange for fast leaf shutters when the opening and closing times are relevant.

 

[vandergus]

The Reveni tester looks interesting, but I cannot see it being any more accurate than mine. It is doing the same thing, measuring how long the light is seen for. The trick is to have very tight code to capture the timings with minimal latency.

I'm not an expert on leaf shutters, so cannot see how a computed shutter speed can be achieved with just one sensor (or else we could use just one sensor for focal plane shutters?) Mine will measure the raw speed of a leaf shutter, but then there will be some error due to the much discussed width of the sensor. If anybody has any ideas, please let me know & I can change the leaf shutter/single laser code.

The appeal of the Reveni tester is not just accuracy but the range of features it has. It does seem to use correction factors for sensor width (I think this is what "Curtain-velocity compensated timing" means on the Kickstarter page) so it should be very accurate at high shutter speeds. But it can also measure true shutter efficiency for leaf shutters by measuring the variation in light intensity during opening and closing. It can measure total exposure at the film plane for calibrating auto-exposure systems and lens aperture values. And it has a variable intensity light source for calibrating light meters. It's a very complete package.

 

[ic-racer]

ISO 516 wants a leaf shutter to be measured with 'Normal' lens wide open, as so:

(Front Shutter = Any shutter in the vicinity of the lens -- ISO 516)

But, if measuring only the shutter (without the lens), one can get a near 'equivalent' measurement with the two measurements as shown here and using the equation:

Assume T1 = T3

Tt = T1 + T2 + T3
To = T2

Te (effective exposure time) = T2 + (T1 + T2)/2

 

[CDSnapper]

Dad has completed the mk2 version with lasers able to focus to a much smaller point on the focal plane. Thanks again all for the assistance and to Niglyn for the code and the idea

 

[Niglyn]

Hi CD, thanks for the update. Glad it is all working ok for you.
Good to see standard light diodes work ok. The modules have an inbuilt ic with Schmitt trigger & amplifier.
The code only accepts the first pulse from the sensor, so a good hit from the laser should give a nice pulse from a light diode.

Hopefully you have tested the lasers to ensure thy are not too pokey & damage the shutter curtain.

 

[Andreas Thaler]

Fascinating work

 

[Niglyn]

Hey everyone! I've ordered the parts needed for the ESP32 build, and while I'm waiting for them I am planning on building the enclosure, fitting everything etc.

Ihave opted for the three sensor diagonal layout design, and I was wondering if all of the three laser values are displayed on the LCD at the same time or not?

Hi, The LCD shows the outer two sensors. The LCD is a legacy left over from the older Arduino design & there is no space on it for three readouts.

The tft display and computer screen show all three sensors and more details than one should ever need.
Keep us updated with your build.

 

[Niglyn]

Hi nusproizvodjac,
The pin sometimes labelled as GND, between the pins 19 and 21 is not a ground connection. It is an error that is copied onto many boards.

I have looked at the PDF, pin 19 has a purple wire going to the tft,
pin 21 has a orange wire going to the LCD.
The pin between pin 19 and 21, is not connected to anything.
I cannot see anywhere on the ESP32 wiring diagram pdf, that shows pin 20 connected to anything?

If you only wish to test horizontal shutters, arranging the three sensors horizontally, rather than diagonally, will make aligning the camera far easier.

 

[koraks]

Concerning those GND pins: what you can do is take a multimeter, set it to continuity mode (many meters 'beep' when you contact both pins in this mode) and then verify if pin 20 is in contact with the other GND pins.
Alternatively, just connect the display GND to any of the other GND pins on the ESP32 module/expansion board. On the screw-type expansion board shown in your post, you can fit more than one wire into a single screw terminal if necessary. Just make sure they're all firmly connected once screwed tightly down.

 

[Niglyn]

Hi,
certainly not spamming.
Ask as many questions as you wish. It will help others and also help me make any changes or upgrades required.
English is not everybody's first language, so sometimes further explanation or re-wording can help.

The pin you circle, is top right on the board it is GND, not pin 20.

The pin that must not be used is six pins below. There is an error on the boards, and being chinese, the same mistake gets copied by the clone makers, rather than it being corrected.

Pin circled in purple is the pin that must not be used. It is above pin 19 and below pin 21.

Please keep us updated on your progress.
Regards,
Niglyn

 

[koraks]

A word of advice for anyone trying to unsuccessfully flash the Blink code, I presumably used a cable that was not a data cable but a cable which was used for charging my headphones, which probably has two cables rather than four or five.

Yeah, that's a common problem. Good to hear you tracked down the issue yourself! It can be a frustrating problem for sure.

 

[Niglyn]

It lives! I've only assembled it haphazadrly to test the alignment and see of everything works correctly, and so far so good. At first nothing showed up on the LCD, but adjusting the pot made the letters appear.

What I'm observing is that at 1/2000 all of my electronic cameras are showing 1/1650 or something similar, but I suppose that it's due to the sensor/laser not being positioned well and the sensor not being housed. Up to 1/1000 it's spot on.

I've prepared a couple of project boxes and drills to place the sensor behind a 0.8mm hole. A friend of mine has made me a drilling template in CAD so that the sensor holes are evenly spaced.

Good to see you have it up and working. Drawing in cad is ok, providing the printer can print it accurately. Better is a mill with digital readout, used to drill the holes.
Real exposures are 1/30, 1/60, 1/120, 1240, 1/480, 1,960, 1/1920
going backwards, 30 seconds is actually 32 seconds.

 

[Niglyn]

So, I went a few steps back, because something isn't right. I've taken everything out of the boxes, and wired only one sensor and one reciever. So far so good, the laser shines nicely, the reciever detects the laser.

When the reciever is wired to the third pin, which would correspond to "Laser 1", it is detected and measures nicely.
However, when the reciever is wired to the fourth pin, which would be "Laser 2", it is detected, but it does not measure the shutter speed values. I believe it's also the case with the middle position, but I haven't tried it, I might try later.

Any insight to what the problem might be? Anything helps, I'm at my wit's end... Thanks!


EDIT: As I've suspected, neither Sensor 2 or Mid sensor detect any speeds. Tried four different recievers and modules, and it's all the same. They are detected in the alignment utility, but they don't measure. Strange really. I'll flash the code again, and see if it sorts out.

Put the camera on B and open the shutter. Do all three lasers shine though the gate and hit the receivers?

It is my guess that the camera is not aligned so all three lasers cannot shine through the gate.
Having the three lasers arranged diagonally does make it harder to align, as the camera has to be aligned both horizontally and vertically.
I have mine all in a row, s I don't have any vertical shutters.

Other thing you can do is to get a piece of card & cut a slot in it, to simulate a slot in a shutter curtain. You can now move this across the sensors to simulate a shutter passing.