Making a 3 sensors shutter tester - part 1

This is a short series about my attempt of building a real, high precision shutter tester from scratch.
All credits for the idea and theoretical implementation go to the mastermind behind this project, Niglyn (@wibbley1).
You can find everything you need to build this tester on his github page:
github.com/bil...
The documentation you'll find there goes as far as to link to the exact items you'd have to buy to get your project done.
You can also follow the dedicated thread on Photrio, where you can also ask questions and seek advice.
www.photrio.co...

[@misterchair]

the rubber strip is for a seal between the lid and base of the box, it glues into the channel around the lid.

[@wibbley1]

Hi, This is my design. Great to see a tube of it being built. I have not watched part two yet, so don't know if Alin likes it! I don't have the facilities to build production units and it is really not viable to sub-out production. So instead I wrote detailed plans to allow people to build one themselves. It uses cheap off-the-shelf parts without the need to make printed circuit boards. This design is as accurate as a 'professional' tester. All firmware, plans, build guides are free and always will be. There is an active photrio thread, where help & guidance can be sought. There is an updated version of The Shutter Tester, same hardware but now adds a rotary encoder. A simplified screen layout (toggle between this and the original) with a much larger typeface has been added as well as other functionality including shutter diagnostics.

[@AlinCiortea]

@@wibbley1 my findings and conclusions are in part 3. It seems you've already made some of the changes I was taking about :)

[@arekguinness2342]

Alin you are crazy 😉 The project looks serious. I keep my fingers crossed that everything will work out 👍

[@AlinCiortea]

@@arekguinness2342 stay tuned, because in a couple of days I'll have some clear results ;)

[@atf2940]

Interesting project. Personally, I think one emitter/sensor is perfectly fine to make all measurements needed. As you say, you just hold the camera so that you make measurements at the middle and the sides of the shutter. With my Lego tester I have no alignment issues. The sensor is fixed rigidly, the laser is mounted on bluetac and can be readjusted minutely if needed. I actually prefer this simple set-up because it allows to make measurements at any point in the focal plain. I can thereby check how much acceleration I have at which point. But making three measurements in one go is, of course, more convenient. Three remarks. 1. The elastic is a rubber seal that fits into the groove of the large box. You won't need it unless you wish to test your shutters in pouring rain ;-) 2. You bought pairs of mating lasers and sensors. Keep in mind that the sensor is tuned to the 650nm (+-) of the laser. White light will cover that part of the spectrum but most of it will be wasted on the sensor. Perhaps a broad spectrum sensor will be better suited. A case for trial and error. 3. Sensors and emitters come with the correct R and C values on those little boards. Curious to see where the additional resistors and capacitors will go ... 4. One thing that is a game changer for the faster speeds is masking the sensor with a narrow slit. (Thanks to Niglyn for this tip.) Perhaps a very small circular hole will also do the trick, thereby allowing for measuring horizontally as well as vertically moving shutters. Good luck and looking fwd to seeing the result!

[@AlinCiortea]

@@atf2940 the combination of laser emitter and receiver is certainly the best but in my case the film gate sensor variant seems more flexible and usable. The small mask in front of the emitter or receiver also crossed my mind and I suggested it on his thread at some point but if I remember correctly I wasn't the only one. Eventually Niglyn added to his code so now the tester 'knows' to adjust for the inherent width of the laser. In my case, the masks are actually the holes in the sensor case. As always, thank you for your suggestions :)

[@wibbley1]

@atf2940 Hi, two sensors are needed to measure the curtain speeds. These need to be balanced else uneven exposure will occur. With just one sensor, one would have to make multiple tests at either side of the gate. I found the block of wood vertical sensor frame the best (Lego even better :o). If needed, make another for vertical shutters. This way, alignment of the camera only needs to be left-right. The height does not matter. 1. Yes. I never fit it. 2. Indeed. The senor will react to broad spectrum light. Whilst I built a sensor film back & LED light, I still prefer the Lasers. 3. If trying to make a film back sensor, the space is too small for the module PCB, so the sensors are fitted without the module and require the capacitor & resister to be fitted to the sensor legs. 4. This is the problem with most testers (not mine :o), they measure the sensor width and the width of the slit. The problem with a small hole mask is getting enough light through it. Again, the Lasers win here. Kuroshio use a thin slot with a bespoke long-thin sensor in the same plane as the shutter, to gather the light. These are unobtainable.

[@mattdyer9544]

I've recently invested in a 'new' shutter tester. A £4 portable CRT display that works well enough for me to get an idea of shutter speeds and can sit on my desk. I can also take a photo using my digital camera and compare it to a known good camera/count the scan lines to get a more precise read. Its certainly not perfect and I'll be interested to watch the rest of this series and maybe give a go at making one myself.

[@AlinCiortea]

@@mattdyer9544 I'll probably never give up the CRT monitor because it's just so convenient to use for the initial shutter setup. And so far, with my FSU cameras at least, even using the CRT alone yields perfectly usable results.

[@sonuvasteele2226]

So is there a way to make this happen on a KZbin video? Like instead of having a whole device, a video could be made with the light going across?

[@AlinCiortea]

@@sonuvasteele2226 I'm not really sure I understood the question...