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#1 Paul Bruening

Paul Bruening

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Posted 26 October 2006 - 08:25 PM

Hello all,

Just saw The Long Goodbye. The Netflix copy had extras including the flashing techniques Vilmos used. After seeing this, I am more confused about flashing than I ever was. They discussed flashing quantities in terms of percentage. What the hell am I supposed to do with percentages? I need a system in stops. I know about using a white card or grey card. I know about pulling the focus out. I know about a balanced light feild accross the card. But, what stops do I set to get a percentage?

Let's assume an 18% grey card for the sake of this string. Also, let's assume I use a Sekonic L-558's globe to set the f-stop. As well, assume I'm pre-flashing in-camera. If I set the lens precisely at the reading on the meter, what percent flashing will that be? Is there a predictable way to convert every percent unit of ten (10%, 20%, 30%, etc.) into f-stops?

Once that has been established, how do I accurately compensate during picture exposure for the addition of light from flashing? Does a one stop flashing mean I should expose the film as if it were a stop faster (i.e. ASA 250 film shot at ASA 500) or do I expose it normally since the flashing changes subject blacks and not so much subject whites?

Vilmos seemed to think flashing would become the technique of the future for night-time exteriors, allowing the production to avoid costly lights, generators and the associated crew. How well does flashing hold up to, say, one or two stops flash and one or two stop push processing?

As you can see, I'm fishing for more precise information that I can make decisions with right on the set. This whole percentage thing doesn't translate into any lens setting decisions I know how to work with.

Thanks in advance for anyone tackling these questions,

Paul
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#2 David Mullen ASC

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Posted 27 October 2006 - 02:25 AM

It doesn't even matter what number of stops equals what percentage. The percentage figure is fairly meaningless because anyone who flashes has to test to determine the level they want for the show. So whatever method they use, they test different percentages, different stops, whatever, and pick what they like. A 20% flash on a Panaflasher is not necessarily the same level of flash from a lab that uses 20%.

It's supposed to be some percentage of overall density I assume but it really doesn't matter. You test different levels and then pick and choose based on the results.

In terms of improving shadow detail for night exterior work (flashing really works on the bottom of the exposure curve first before it affects highlights) in truth, it doesn't help a whole lot. Generally a tiny amount of flashing (7% to 10%, let's say, on a Panaflasher) will lift up some low-end detail that is normally buried, but otherwise, any more flashing and all you are really doing is milking up the blacks. Certainly flashing is not a replacement for lighting to get enough overall exposure; it just helps reduce the fill level needed to some minor degree.

So pick some method of exposing the grey card for the pre-flash and test it in increments of a stop and print and project the results... and pick what you like.

Pushing is different -- there you are increasing the density during processing of areas that received some exposure in the first place, usually to compensate for underexposing the information. But it cannot enhance information that is missing because it wasn't exposed.

Flashing to a negative adds density to the low-end of the picture information in the form of an overall veil or fog of light that can give the illusion of decreased contrast because of the lack of true blacks. It also brings up some low-end detail that might be buried in the normal contrast of the neg & print stock.
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