Flash contacts and standards

[ironringer]

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I am interested in using older 1980s-1990s "Automatic" or possibly even "TTL" flashes on the M240 and M10 cameras. The first "filter" to identify suitable flash units is their trigger voltage, which is easy to measure from their hot shoe connections. Several older flashes have low trigger voltages, under the (conservative) safe 24 volts recommended by Leica. Among those are the sturdy Nikon SB-15 (a fine and capable unit), and the smaller Pentax AF 160, which does a good job in a lightweight package.

My recent find of a treasure in a thrift store - a high quality Nikon SC-28 TTL flash extension cable - "triggers" my research into flash connections by camera manufacturers. Specifically, what electrical connections are positioned where on a camera shoe (and on a corresponding flash), to perform what functions? An initial broad question is: have any camera manufacturers defined STANDARDS for the position and use of these connections?

Internet research shows there are ISO standards for the basic "hot shoe" connections (the center post and shoe sides contacts), to enable a hot shoe connection to a Manual or Automatic flash. Are there any broader and advanced standards used by camera and flash manufacturers, to define the many other connections used on modern cameras and advanced "TTL" flashes? If broader standards exist, are they public information?

I wonder if Leica, at least for the M240 and M10, uses flash connections that are similar to the contacts I see on the modern (2011-current) Nikon SC-28 connectors? Physical positions on both seem similar, but the functions associated with the contacts may be different in the Leica and Nikon systems.

An interesting world, and there is LITTLE documentation available about how these flash connections are defined and used. Maybe much of it is "proprietary", but I don't see much practical reason for keeping this information hidden. Ideally standards would be used (like USB and HDMI cables) so that there could be "mix and match" use of cameras, flash extension cables, and flashes among different manufacturers.

 

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[Luke_Miller]

I use both the Nikon SC17 and SC28 cords with my M 240 (and M9 previously). Their fit the Leica hotshoe seems the same as with a Nikon body.  Their pin locations are a very close, but not perfect, match to the Leica pin connections. In my experience a Leica TTL flash will work properly with these cords.  But due to the slight misalignment of the connections any movement of the flash in the cord hotshoe or cord in the camera hotshoe can disrupt communications. I find the cords useful in handholding the flash off camera to avoid the effects of direct flash.  The flash dangles from my left wrist using a wrist loop attached to the flash hotshoe end of the cord.  I focus normally and then grab the flash and hold it high and to the left, pointed at the subject or bounced.  The is particularly useful with flashes like the SF24D which does not tilt or swivel. I learned this technique from Sean Reid on his website.

[ironringer]

Thank you Luke for this pertinent comment and advice - very useful.

I researched further on the web using "flash contacts pinout", and found many pictures (see below) of various flash contacts arrangements on different cameras, with definitions of what "pin" does what function. Each manufacturer uses a slightly different number and position-function of flash contacts, so it seems there is no standard arrangement, unfortunately. Poor coordination in this industry.

The Nikon TTL flash contacts are similar to those of the M240, as you say. Certainly the non-TTL flashes using basic "hot shoe" contacts should work fine in their Manual and Automatic modes, using the Nikon SC-17 or SC-28 (almost identical cables, except for colour and lock-clamp method) extension cables. Only flashes with low trigger voltage under 24 volts should be used on modern cameras.

 

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