From: "John Coyle"
I started with blue flash-bulbs in 1967. They had a long burn time (1/40 to 1/60 second) with a rapid climb to full output, then an even peak output followed by rapid drop-off at the end of the burn. The 'M' setting on the camera I was using at the time (a Voigtlander Vito CD) was what you used for these bulbs, although the camera also had an 'X' setting for them new-fangled electronic flashes. The settings ensured that the shutter opened first, then the flash fired. The shutter speed had to be set at 1/30 or slower, so that the flash output occurred while the shutter was fully open, otherwise you'd get a black bar at one side or the other, where the film was unexposed. Aperture was calculated from the guide number of the flash and the speed of the film, and I found I could seldom close down beyond f8, even at 400 ASA. The bulbs were coated with a blue substance to match the colour temperature of noon daylight, so fill-in flash was possible. There was a third shutter setting option, FP ('flash-peak'), which would allow the use of bulbs designed for focal-plane shutters, and these you could use at speeds from 1/30th upwards to 1/1000th, although I never had a camera with that facility until I got a Rolleicord, where you could use the 'V' setting to fire the flash at any speed - basically because the shutter was a between-lens type. Open to correction on some of the technicalities, it's been a long time since I had to think about such matters!
I think the M-sync fired the bulb first and then opened the shutter. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
