Digital shooters can be be spoiled by the wonderful developments that the major manufacturers have made with camera sensors and electronic circuitry. As time has gone on the cameras have been given the ability to make pictures under darker and darker conditions with cleaner and cleaner results. In many cases digital shooters have never thought to turn on any additional artificial light. And many have eschewed it as being somehow "impure"...
Those of us who shot film, and old film, had no such qualms. When we needed light indoors we put over-run incandescent bulbs into domestic lamps, set up photoflood lights, or reached for flash guns and flash bulbs. The lucky and adventurous had access to studio strobe outfits that looked like they came out of either a Thunderbirds set or the ark... I say adventurous because they were working with strange cables, industrial plugs, and high voltages. It was never a good idea to stick your fingers in there...anywhere...
The portable reflector guns sometimes had folding fan reflectors or polished round metal bowls. You plugged in AG-1, Press 25, or other bulbs in them, added a 22.5 volt battery and tried to synch it to your shutter. Sometimes the designer of the flashgun and the camera had agreed on the sort of synchronising connector they wanted to share - sometimes not. There was a large range of proprietary designs for plugs and sockets and frequently you were holding a gun that would not attach to the camera. Even Leica was guilty of this sort of thing...
The low-tech let out for this was to take a picture in dark conditions - dark enough so that you could use one second for the shutter speed. Probably a tripod situation, though if it was dead dark you could get away hand-held.
The trick was to fire the shutter on one second and during the time that the shutter escapement was buzzing away you fired the flash by means of an "open" button on the back of the gun or simply shorting out the terminals of the synch cord with the tip of a Biro. The picture was illuminated by the flash and the negative did not know that you were the sort-of-wireless link in the process.
No relevance today? Not so - I frequently need to shoot studio stuff with lights in several paces and sometimes they need to be small lights concealed in structures. I turn out all the lights, open the shutter, and then use a portable speed light to pop wherever needed. Many of the speed light flashes can be shot in Manual mode and throttled down to 1/64th or 1/128th of their full power. These and low ISO settings mean you can have quite a degree of spot control.
Even if the need is more flash power altogether with big studio units, you can use the same procedure. Dark studio, open shutter, then flash once, twice or four times to get two more stops of power past the top wattage of the units. It pays to turn off modelling lights unless you need more warmth in the scene or if you are frightened of the dark.
But anyone who used some of the old Lumedyne or Norman flashes isn't afraid of dark. Lightning, yes...
