M and F Flash Sync

[focus_on_infinity]

I have an older shutter (Kodak Supermatic) that only has M and F sync - no X sync. I'd like to use it with my newer flashes and triggers. My understanding is that M triggers 14ms before the lens is at full aperture, and F is at 5ms. It seems there are probably two possible solutions to this problem

1.) delay the trigger to my flash, using a small electronic timer
2.) HSS, which keeps the flash on longer

There are a couple of downsides to these: 1.) it wouldn't be necessary to make an external device if my flash had a built-in delay compensation feature (which it could easily add through a firmware update), but it doesn't. and 2.) seems like it may be inaccurate when using a flash meter.

How have you dealt with this issue?

 

[mmerig]

Try using a slower shutter speed, say 1/30 sec, at the F setting. 5 ms is 1/200 second, so the 1/30 sec opening should catch the flash given that relatively short delay.

 

[Dan Fromm]

The Flash Synchromatic will trigger X class (electronic, triggers when shutter is fully open) flashes. To get X sync, don't cock the synchronizer cocking lever.

 

[focus_on_infinity]

The Flash Synchromatic will trigger X class (electronic, triggers when shutter is fully open) flashes. To get X sync, don't cock the synchronizer cocking lever.

Is that this thing? I've always wondered what that was for.

 

[Dan Fromm]

Yes.

 

[shutterfinger]

Download https://learncamerarepair.com/product.php?product=289&category=2&secondary=35
Open the shutter, bypass the 10K ohm resistor with a piece of copper wire or replace it with a piece of copper wire then reassemble the shutter.
It will now be X sync.

 

[hsandler]

I don't think HSS on a modern flash is likely to work. I looked into this in conjunction with using my Nikon flashes with an old focal plane shutter. Although it should work in theory, I believe in practice you will find most HSS systems depend on extra control signals from a compatible camera to tell the flash precisely when the slit begins to travel across the focal plane.

Creating a brief delay of the flash trigger current using either a digital timer or some kind of resistor-capacitor filter (finicky, but easy enough) should work.

I don't believe the advice to simply use a low shutter speed on M or F sync will work. It works in the reverse situation: using flash bulbs on an X sync shutter. But here, on M or F sync, the flash is triggered before the shutter blades open, and the flash will be over in under 1/1000s in most cases, so even a long shutter opening will miss the flash.

Dan's advice sounds best: the shutter had X sync available all the time; an unmarked feature. Good to know.

Shutterfinger's advice intrigues me. From what I can figure out from the manual, the 10k resistor is just to bleed static charges from one flash contact to the case ground while preventing outright shorting of flash circuits that may contact the case. I don't see how it would have an effect on the flash timing. But perhaps Shutterfinger meant in conjunction with the (unmarked) X sync, if somehow the resistor was causing a delay in the triggering of the flash.

 

[wiltw]

I don't think HSS on a modern flash is likely to work.

Good point. A flash must be in HSS mode, AND the camera triggering it must be able to SEND the command for HSS flash in advance, rather than simply the Trigger which triggers non-HSS mode.. A Canon eTTL flash or Nikon iTTL would be examples of xTTL compatible flash units that expect a command from the body.

Unless you are using a studio flash unit which has a forced mode to prolong light output even with no command coming from the camera.

 

[shutterfinger]

The 10k resistor isolates the right bipost pin from the shutter case. The left pin is connected to the right bipost pin when the shutter blade controller (1) reaches the end of its travel, shutter blades full open, and contacts the end of the copper contact (2) that is connected to the left bipost pin. At the same time switch (3) contacts are closed connecting the right bipost pin to the left bipost pin triggering the flash.

With the resistor bypassed the bipost pins are connected when the controller (1) reaches the end of its travel triggering the flash. Switch (3) is no longer affecting the triggering.
I'm not familiar with HHS.

 

[Dan Fromm]

Charles, I just did an experiment that I hope the OP will do.

I took out a Flash Supermatic, connected a Paramount bipost-to-PC cord to it, plugged the cord into and an electronic flash, turned the flash on, cocked the shutter and fired it. The flash fired. I'd set the shutter's diaphragm to wide open and looked through the lens at the area the flash illuminated as I fired the shutter. I could see the entire opening, it wasn't occluded by the shutter blades. The x-sync works. What I saw is entirely consistent with the "Pacemaker Instructions" manual posted here:
https://onedrive.live.com/?authkey=!AMvNyd9CqLT7ul8&id=8D71BC33C77D1008!13955&cid=8D71BC33C77D1008 Second row, fourth from the left.

 

[BrianShaw]

Here y’go... albeit unmarked on the shutter, not a “hidden feature”:

“When using a high speed gaseous discharge tube which does not have a built-in relay or solenoid merely connect its cord to the contact posts and cock the shutter in the normal manner. Do not cock the synchronizer cocking lever. The tube will then be flashed in synchronization with the shutter as the body release or shutter release lever is operated in the normal manner.“

 

[focus_on_infinity]

Here y’go... albeit unmarked on the shutter, not a “hidden feature”:

“When using a high speed gaseous discharge tube which does not have a built-in relay or solenoid merely connect its cord to the contact posts and cock the shutter in the normal manner. Do not cock the synchronizer cocking lever. The tube will then be flashed in synchronization with the shutter as the body release or shutter release lever is operated in the normal manner.“

Yep, certainly looks like Bob's my uncle. Thanks!

 

[shutterfinger]

On some versions of the M-F Flash Supermatic the switch is locked out and no flash sync is operated without the delay being set. In production changes were made. Test your shutter.

 

[RalphLambrecht]

I have an older shutter (Kodak Supermatic) that only has M and F sync - no X sync. I'd like to use it with my newer flashes and triggers. My understanding is that M triggers 14ms before the lens is at full aperture, and F is at 5ms. It seems there are probably two possible solutions to this problem

1.) delay the trigger to my flash, using a small electronic timer
2.) HSS, which keeps the flash on longer

There are a couple of downsides to these: 1.) it wouldn't be necessary to make an external device if my flash had a built-in delay compensation feature (which it could easily add through a firmware update), but it doesn't. and 2.) seems like it may be inaccurate when using a flash meter.

How have you dealt with this issue?

For what it's worth, The Gossen flash-light meter Let's you set the trigger delay for accurate easurements.