Flash primer

[froyd]

Got an old Promatic 4000 flash sitting around and thinking of using it with a couple of older cameras. Can anybody confirm that I have the basics right? I'm particularly confused by the 1/16 setting.

The flash has three main settings: 1/16, M, and A.

A- is AUTO: pick among three different settings, set f stop on the lens, make sure subject is within range and fire away, letting the sensor control the flash output. Shutter speed can be set at X or below (well, the whole range on the Rollei). The slower the shutter speed the brighter the backgroung beyond the reach of the flash.

M- is Manual: determine distance to subject, use slider on the flash unit to determine f stop (or calculate f stop= GN/ Distance @ ISO 100)

1/16 - I'm assuming this is 1/16 flash power output. Is this meant for fill flash? E.g. Shooting ISO 100, subject is 10 feet away in bright sunlight: set shutter at 125 and diaphram at f16 for proper sunny 16 exposure and pop flash at 1/16 setting to open up shadows? Should I be at f11 instead (prper f stop for M mode at the given distance)?

HELP!

 

[charjohncarter]

1/2 is one stop less, 1/4 is two stops less, 1/8 is 3 stops less, and 1/16 is 4 stops less. At least that is the way it is on my power selections on manual flash.

For fill flash you get the distance f stop on manual by GN calculation to say f5.6 then set the camera on f8.0 or f11 depending on how much fill you want and now set the ambient shutter speed. Your flash will be 1 or 2 stops less that the ambient f stop and shutter setting giving you flash fill.

OR you can set the auto setting for your ISO say f5.6 and then set your camera for again f8.0 or f11 and again set the shutter to the desired ambient speed.

 

[froyd]

1/2 is one stop less, 1/4 is two stops less, 1/8 is 3 stops less, and 1/16 is 4 stops less. At least that is the way it is on my power selections on manual flash.

For fill flash you get the distance f stop on manual by GN calculation to say f5.6 then set the camera on f8.0 or f11 depending on how much fill you want and now set the ambient shutter speed. Your flash will be 1 or 2 stops less that the ambient f stop and shutter setting giving you flash fill.

OR you can set the auto setting for your ISO say f5.6 and then set your camera for again f8.0 or f11 and again set the shutter to the desired ambient speed.

Thanks for the info on 1/16. Now that I know that 1/16 = 4 stops less flash output, what do I do with this setting? Sounds like the equivalent of a ND filter for the flash head... if I need to cut the distance to subject while keeping the aperture. Sounds like it would turn my GN100 into a GN6.25. Is that right? Is this the only purpose of the 1/16 setting?

 

[charjohncarter]

Thanks for the info on 1/16. Now that I know that 1/16 = 4 stops less flash output, what do I do with this setting? Sounds like the equivalent of a ND filter for the flash head... if I need to cut the distance to subject while keeping the aperture. Sounds like it would turn my GN100 into a GN6.25. Is that right? Is this the only purpose of the 1/16 setting?

I use 1/16 all the time, but you are right. Reducing depth of field, and also saving batteries and recycling time are all features of 1/16. You can move your flash closer to the subject and get the same flash strength, but you do get a different flash profile. A closer flash give a less harsh look. Also, I know you don't have two flashes but 1/16 can be used with a 1/4 or 1/8 powered flash to be a accent flash in traditional portraiture.