Camlogix SH-T2 shutter tester instructions

[james_barber4]

I've come up with a camlogix shutter tester from an estate and there was no instructions included.  Google has not been helpful, so I'm asking the community to see if anyone has the instructions they can send me, or at least tell me how to calibrate it.  Thanks.

[rodeo_joe1]

If it's like this one, it looks pretty straightforward, with very few controls to master.

Having built a DIY shutter tester, they're not very complicated once you have the pulse-width counter sorted.

There's a light sensor in the black plate that's positioned in the film plane of a 35mm/rollfilm camera, or has an LF lens+shutter placed over it. 

It looks as if an external light-source must be provided that's shone into the lens. Notice the desk-lamp shown on the cover of the instruction book. 

The 'Cal' knob looks as if it adjusts the sensitivity threshold of the sensor. I surmise that you just 'twiddle' it until the pulse-counter triggers reliably when the shutter is fired. 

So, in summary: 1. Fit the sensor plate behind the shutter. 2. Shine a light source into the lens. 3. Fire the shutter and see if the millisecond counter triggers and counts. 4. If no triggering, then adjust the sensitivity with the Cal knob. 

The thing can be tested by just obscuring the sensor with opaque card or the like, and seeing if it starts counting when the card is removed. 

I don't know if it's auto-ranging or not, but I can see no range switch. 

The evenness of transit of an FP shutter can be checked by moving the position of the sensor plate across the film-plane. You should get the same time-reading, +/- about 10%, at both ends of the shutter travel. 

P. S. Best not to use a mains LED bulb as the light source. Some have a deep flicker characteristic that could easily affect the count. That thing looks as if it predates the use of mains LED bulbs, so best to use a 'period correct' filament bulb. 

Edited January 21, 2023 by rodeo_joe1

[james_barber4]

Hey Joe, thanks for the info.  It is like that one.  Seems to work well, I just tested some LF shutters on it using the steps you provided.  Would you happen to know why there is an indicator bulb next to the calibration knob?  That's what threw me, I've tried a number of different things and the bulb doesn't come on.  However, it seems to work just fine so I not complaining, just wondering.  

[rodeo_joe1]

9 hours ago, james_barber4 said:

Would you happen to know why there is an indicator bulb next to the calibration knob?

Just a guess, but it might be meant to indicate when the sensor is triggered - I.e. has sufficient light. 

Another total guess: With the shutter open and light-source in place in front of the lens; is there a position of the Cal knob where the Ind LED lights? Because I had to incorporate a triggering Indicator in my homemade shutter tester. It makes it easier to tell when you have enough light and good alignment through the lens.

Incidentally, measuring an FP shutter properly really needs the light source to be sharply focused on the sensor. Something that's not easy to do unless your lamp is at some distance from the lens. Hence the indicator LED to check alignment of the light. Having said that, many commercial shutter-testers just use an opal diffused light screen in front of the camera. Good enough I suppose, if you're not too fussy. 

FWIW, my homemade tester was just a front-end to enable a digital storage oscilloscope to capture the shutter pulse cleanly. However I independently arrived at the design of a 35mm by 60mm sensor plate that would fit across the film rails of either a 35mm or 120 camera.