ND Filter for Daylight Flash?

[Danner]

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Please help me decide what neutral densit filter factor to buy (3-stop, 4-stop, 6-stop) ... ?

For shooting ISO 100 in an M6 (1/50 sec) and using my Metz 34 CS-2 auto flash.

What I want to do is use daylight fill flash (DFF), but punch it a bit to overdo the effect, sort of an old-school reportage look.

Sunny-16 gives 1/50 at f/22.  The Metz aperture options are f/2, f/4, and f/8 at ISO 100 (it is a simple little flash).  Light will be less than sunny-16 most times, and my preference is to shoot at f/4 or so, but have some adjustment range to deal with varying light.

Anybody use DFF with an M6 and film?  Any thoughts on a choice for filter factor?  I'm leaning toward 3 or 4 stops.  Maybe 6?

Thank you for your thoughts.

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[Pyrogallol]

A neutral density filter will reduce both the flash and daylight effect. You could just use a slower speed film and combine that with a speed reducing developer. To really get an old look you would need a larger format camera with a leaf shutter that could synch at any speed.

[Fotoklaus]

What about a reflector? Very useful sometimes. A piece of white styrofoam could do the job perhaps.

[Danner]

8 hours ago, Pyrogallol said:

A neutral density filter will reduce both the flash and daylight effect. <snip>

Oh snap!  I did not think of that, ... recalculating ... LULz...

[250swb]

@Danner I've just done a Google search and there are so many links for this it's hard to choose just a couple, but if you Google 'How to shoot with flash like Bruce Gilden' I think eventually you'll find an answer. Bruce Gilden is of course the supreme street photographer using his Leica M6 with a flash, so the answer is out there.

[Pyrogallol]

Even better, google “O Winston Link” to see the ultimate flash photography.

[giannis]

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There are only two ways (and a minor third) to increase the effect of the fill flash and "overpower the sun", i.e. increase the flash to ambient lighting ratio:

1. Use a stronger flash (higher guide number, the higher the better)

2. Use a faster sync speed (impossible given the same camera)

Everything else - ND filters, slower film, etc etc. - affects ambient light and flash light equally and hence doesn't alter their ratio.

Practically speaking, overpowering the sun is virtually impossible with 1/50 sync speed. You would need a flashgun that is 3 stops (i.e. 8 times!) brighter than if you had, say, 1/500 sync. Realistically, getting some of the stronger portable units, say with a guide number ~45 (in meters), you'll be able to match the sun at a distance of ~2m. For instance, say you meter exactly f/16, i.e. 1/100 (say ISO100 film) at f/16. This means f/22 at 1/50 (your sync speed). I.e. that to much that brightness level of the ambient light, your flash would need to be just as strong and have a guide number of ~44=22x2 (GN=f/number times distance). Once you have that flash, set at 2meters from your subject, the fill from the flash will be the same as the ambient light from the sun. Now your settings are f/22 at 1/50. You want f/4. So slap on a 5-stop ND, and you'll get your f/4 photo, correctly exposed, with the fill being as powerful as the ambient.

Again, the biggest constraint with slow sync speed is flash power. If your flash power is virtually unlimited (studio strobes of thousands of wattseconds), you can overpower the sun at any sync speed, given full flash power and a corresponding strong ND to bring the aperture down to the value you like.

[Pyrogallol]

The old time Weegee type street photographers would have been using a 5x4 camera with a leaf shutter and a nice big flash bulb, so they had plenty of flash that exceeded the available light.

[Danner]

Took the M6 & 35 Cron to the farmer's market this morning.  Cloudy, shooting Tmax100 @ 1/50 & f/5.6, and with the Metz auto flash set to f/5.6 as well.  Looking forward to finishing the roll and developing it.