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

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bto

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May 9, 2024
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7
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35mm
Hello,
it shows to be very tricky to place the laser beam at the outer edge of my lens (Zeiss Planar 80/2.8 CB) the shutter diameter fully open should be 26.8 mm. Would it be problem if the outer edge laser is of by 1 mm?
The Hasselblad lens starts with shutter open; 1. shuts fast; 2. opens for exposure time and 3. shuts again. How could I test this with the Shutter Tester. It would be great to have this mode. I could try to beta test the code.

Thank you very much in advance
Branko
 
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Niglyn

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Feb 26, 2022
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Hi Branko,
Yes, I can certainly add a Leaf Shutter Open mode, it waits whilst the shutter is open and then starts the testing routine once the shutter closes.
Give me a few days & I will do this.

As for Laser placement, I don't think 1mm will effect things too much. It will detect fully open a little early and starting to close a little late, so will probably cancel each other out. Make sure you set the Sensor spacing parameter in the Alignment menu.

Shutter Testers are designed to test the shutter only, without the lens, so do not know how testing with the optics in place will change things.
I guess we will find out :surprised:)


Just be careful with a lens, that you do not focus any strong light or Lasers though it and damage the camera, in the same way shutter cloth can be burned by the sun.
 

bto

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Joined
May 9, 2024
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7
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Germany
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35mm
Hi,
the lens deflects the "outer " Laser beam" slightly towards center. Laser distance at front of lens for now is 13 mm. Had to place the sensors at 9,5 mm spacing just at the rear end of the lens.
I started to build a rig to test the lens only. Without camera. At the Hasselblad lenses the shutter could be armed with a flat screwdriver when not at camera.
I 3d printed front and rear caps for the lens which fit in the front an rear bayonet of the lens. To this caps I attached the lasers in front and the sensors rear. Will post some pictures when things start working.

Thank you again
Branko
 
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Niglyn

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Feb 26, 2022
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423
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Surrey, UK
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Hi, new firmware 4_1_0_1b available.

It removes 'Leaf' from the shutter type options and adds....

LeafC This is for testing leaf shutters that stay closed before & after firing (like a focal Plane shutter)
and
LeafO which is for the rich & can afford a Hasselblad :surprised:) where the shutter remains open until it is fired, then closes, exposes the film, opens for the exposure, closes, covers the film & opens again.

It works on my homemade leaf shutter, but not been tried in the real world, so please do not rely on the results until you are happy.

As always, please report back grumbles, complaints or praise :surprised:)
 

dmoriya

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Jul 13, 2025
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Hi,

Can I have access to the code? Thanks! I am also curious why the code is not accessible like conventional open source...
 

japim

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Jul 13, 2025
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1
Location
Cornwall
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Medium Format
Thank you for this tester - finally I can actually check some of my cameras!

I've roughed it out to check the functionality before boxing it up, and have some questions.

  • I have three lasers and three sensors, with the outer two at 32mm centres. Does this correspond to the 32mm in the settings menu, with the third one assumed to be centred?
  • I'm getting the red message "Sens1&M Only>2SL"
  • Which order are the sensors supposed to be in? The wiring diagram shows yellow, green, blue for the sensor connections going to pins 33, 25, 32 respectively, but no numbering. I've put the green in the middle as per the diagram. On 1/500 on the (uncalibrated) shutter I'm working on, I get the attached results showing the curtains aren't very happy at this speed, but consistently wildly out over eight tries. At 1/30, 1/60, 1/125 it's surprisingly even. "Paramater" should be "Parameter".
  • I can't get any results with the two outer sensors plugged in as it is still looking for the third.
  • My encoder counts backwards from expected rotation; is inconsistent in registering rotation and has a 5V pin labelled. I only have experience of valve electronics so this is all new to me. Is this just the switched logic level rather than required supply for the encoder, so connecting to the 3.3V pin as per the diagram is still correct?
Thanks again! This is going to be so very useful, especially with the medium format additions discussed previously...
 

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Niglyn

Member
Joined
Feb 26, 2022
Messages
423
Location
Surrey, UK
Format
Analog
Thank you for this tester - finally I can actually check some of my cameras!

I've roughed it out to check the functionality before boxing it up, and have some questions.

  • I have three lasers and three sensors, with the outer two at 32mm centres. Does this correspond to the 32mm in the settings menu, with the third one assumed to be centred?
  • I'm getting the red message "Sens1&M Only>2SL"
  • Which order are the sensors supposed to be in? The wiring diagram shows yellow, green, blue for the sensor connections going to pins 33, 25, 32 respectively, but no numbering. I've put the green in the middle as per the diagram. On 1/500 on the (uncalibrated) shutter I'm working on, I get the attached results showing the curtains aren't very happy at this speed, but consistently wildly out over eight tries. At 1/30, 1/60, 1/125 it's surprisingly even. "Paramater" should be "Parameter".
  • I can't get any results with the two outer sensors plugged in as it is still looking for the third.
  • My encoder counts backwards from expected rotation; is inconsistent in registering rotation and has a 5V pin labelled. I only have experience of valve electronics so this is all new to me. Is this just the switched logic level rather than required supply for the encoder, so connecting to the 3.3V pin as per the diagram is still correct?
Thanks again! This is going to be so very useful, especially with the medium format additions discussed previously...

Hi,
Yes 32mm sensor spacing is between the outer sensors. The physical spacing must also be set in the setting menu.
(For vertical shutters one would physically place the sensors at 20mm and also set this value in the settings menu).

Pin 33 is the left sensor and pin 32 the right sensor. Lasers point into the rear of the camera.

Error 'Sens1&M Only>2SL'
means that sensor 1 and sensor M have been triggered as the shutter opens but after two seconds or greater, Sensor 2 has not been triggered.
This indicates a very slow curtain, or shutter capping.
(Without The Shutter Tester timing out after two seconds, it would sit there forever waiting for sensor 2 to be triggered)

(L refers to the code-block that found the error, useful for me to know which part of the code found the error)

Do not expect to see 100% accurate shutter speeds. Older cameras using springs will vary from shot to shot. Often slower for the first few, as the old grease gets warmed up.
Using a modern electronic shutter, will give far more consistent results.
Look at the ISO chart for min & max values. Your 1/500s tests look to be fine.

Never try to get all the speeds spot on. It will drive you mad, then when you pick up the camera again, the speeds will be different. As said, just get them to within the ISO tolerance.

The Shutter Tester requires readings from all three sensors to compute the shutter speed and check for errors, so trying to run it without the middle sensor will not work.
(Single sensor mode requires just sensor 1 and leaf shutter modes only use sensor 1 and 2)

If your encoder is working backwards, check the S1 & S2 connections go to the correct pins.
Swapping the wires on S1 and S2 will reverse the direction of the encoder.
Whilst the encoder is marked 5V, it is only a mechanical contact so works happily on 3 volts.

Thanks for the questions, feedback and spell checking :surprised:)

All comments, questions, suggestions & issue reports are most welcome.
It helps me improve The Shutter Tester
 
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Niglyn

Member
Joined
Feb 26, 2022
Messages
423
Location
Surrey, UK
Format
Analog
Sorry, just looked at your averages again. yes something not right with the curtains.
No obvious explanation, strange mid readings are the fastest.
Curtain 2 is travelling faster, which accounts for sensor 2 showing a shorter exposure.
Why it is faster in the middle, possibly second curtain spring tension reaches it's peak here and then starts to loose energy.
 
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