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flashing cinematography postflashing

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#1 Rebecca Brady

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Posted 18 April 2016 - 03:24 PM

Hi guys, 

 

I'm doing a college assignment at the moment and I've been asked to discuss, Flashing and Post Flashing. I know what flashing is but I'm not sure I have ever heard of post flashing. It's not in any of my notes or books and it isn't on any website that I can find. 

 

I was hoping someone here would know, any help at all will be hugely appreciated, even if it's just a point in the right direction.

 

Thank you!  :)


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#2 David Mullen ASC

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Posted 18 April 2016 - 03:37 PM

Technically it means flashing the negative after the image has been exposed, usually at the lab.

But some people using the Panaflasher device (which mounts the unused magazine port) on a Panaflex would say that if the unit is on the the back port it is post-flashing since the light is after the gate but if the unit is on the top port, it is pre-flashing since it happens before the gate.

Pre-flashing, which if done using a film camera pointed at a card, requires that the flashed roll be threaded back for exposure of the image on the same set of sprockets since the flash is contained within the gate area.

Similar is something called latensification, though that is slightly different.
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#3 Ari Michael Leeds

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Posted 18 April 2016 - 04:08 PM

This is frequently, and erroneously described as "percentage flash."

However, the numbers used are not decimals, but densitometery numbers like ND filters.  Every 0.30 is one half the light transmission.  However, with negative film, that has a lower gamma than normal, between 0.15 and 0.20 density is one stop, so something to keep in mind.

This is the "percent" more properly 0.XX that is being talked about, how many points of fog are added to the film either rbefore or after its exposure.

Pre-flash is more pronounced than post, because you're exposing, after which they can't be triggered again, grains before the actual subject is exposed onto the emulsion.


The pre-flash that David mentions above with 35mm, there are three or four peroforations in a frame, so what camera assistants will do is mark an "X" on to the film leader when threading to make sure both the flash exposure and the actual photography use the same frame.  Otherwise, there'd be a line where the flash exposure doesn't cover the frame the actual photography does, a big NO NO>


It's a similar procedure to doing a reg[istration] test where cameras are tested against excessive gate weave.


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#4 David Mullen ASC

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Posted 18 April 2016 - 05:41 PM

From a practical point of view, I don't think it matters much if you pre or post-flash -- I did four features with a Panaflasher and I couldn't tell a difference when the Panaflasher was top (pre) or back (post) mounted in terms of results.  The flash is usually very dim and only affects the information at the toe of the curve, adding to the base fog level as well, a pre-flash doesn't negate the ability of the grains to record shadow information just because the flash got there first, it's all just exposure on top of exposure.

 

I do feel that flashing only adds a minimal amount of extra shadow information, mostly it just lifts the blacks, giving the impression of lowered contrast.  In the days of photochemical post, that lift would have allowed low levels of detail to become more visible in a print made off of the negative, but for D.I. work, there is less advantage to flashing since you can lift information up in the color-correction to become visible in images with a display contrast gamma setting applied.

 

Latensification is a bit different, the idea there being that an extremely low and slow level of exposure to light might increase the speed of the stock in the shadows by adding photons to grains that were on the verge of becoming "developable".  It was mostly used for astronomical still photography.

 

"Picnic" and "Camelot" are example of early flashing in Hollywood films -- with "Camelot" the flashing was done in advance to the rolls before being used.  If flashing had been used for "Picnic", I think it was just for some day scenes. It's not well-documented, but there was an issue of American Cinematographer about "Camelot".


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#5 Tyler Purcell

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Posted 18 April 2016 - 07:32 PM

Riddle me this one David... can you flash an IP instead of camera negative?
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#6 David Mullen ASC

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Posted 18 April 2016 - 07:51 PM

Sure, you can flash any photosensitive material -- when you flash an interpositive (IP) or print, you fog your whites down to grey, darkening them, rather than lifting your shadows and your blacks as when you flash a negative or internegative (IN), dupe negative.  Anyone who has accidentally exposed some photographic print paper learns what happens to your whites when you fog the paper.
 
Supposedly Storaro flashed some of his prints that he used the ENR silver retention process on, lowering the contrast a little by softening/darkening the highlights (the ENR process adding contrast to the shadows and making the blacks blacker.)  I heard he did that on "Reds".  I believe that Owen Roizman heard about this and decided to flash the interpositive of "Tootsie" but I don't know if he used the ENR process on the prints.
 
I seem to recall Technicolor sometimes flashing their b&w positive matrices before making dye transfer prints from them, in order to control contrast better.
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#7 Tyler Purcell

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Posted 18 April 2016 - 10:34 PM

Right, I guess my question is... can you do the same thing in the lab after you process the camera negative.
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#8 David Mullen ASC

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Posted 19 April 2016 - 12:59 AM

If you want the effect of a flashed negative but you had already processed it, you'd have to flash a dupe negative but it probably wouldn't be quite as interesting in terms of its affect on shadow detail. Plus all of this assumes a photochemical post and release print, otherwise you'd just create the flashed look in the D.I.
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#9 Ari Michael Leeds

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Posted 19 April 2016 - 03:10 PM

Plus, flashing an intermediate is cheating, kinda like shooting a B&W movie on color film, or, shock, digital!  Sacrilege!!!  :-D


You're right, it probably is very little effect with pre- or -post-flash differences if it's slight, say only 0.30.  I remember this when I was doing double exposures, or more, multiple exposures in still photography, and the earlier exposures, would pick up the detail and the later ones would be less pronounced or not come out.

Granted, these were both in-focus subjects written over one another, but in theory at least, maybe only evident with more flash exposure, the pre is "using up" the silver sites first, whereas the post the image info is already on there.


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#10 Tyler Purcell

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Posted 19 April 2016 - 06:00 PM

If you want the effect of a flashed negative but you had already processed it, you'd have to flash a dupe negative but it probably wouldn't be quite as interesting in terms of its affect on shadow detail. Plus all of this assumes a photochemical post and release print, otherwise you'd just create the flashed look in the D.I.


Yep, that totally makes sense. Doing it on the camera negative is the only way to get the proper results.

I haven't ever thought about flashing camera negative because I've aways been able to adjust in post.
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#11 Dirk DeJonghe

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Posted 19 April 2016 - 10:41 PM

After many years of remaining dormant, flashing is now used in our lab quite often these days when making proper internegatives from positives or reversal originals. We mostly use 200T stock preflashed and Pull processed to a particular gamma to get really good internegatives. This method is also used with the current crop of internegative stock from Kodak which is really 50D in longer lengths and on polyester base.


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#12 Peter Phillips

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Posted 20 April 2016 - 04:13 AM

Would I be wrong if I considered flashing as an alternative to push processing? Different effect for sure, but you can rate the stock faster in a way, right? 


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#13 David Mullen ASC

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Posted 20 April 2016 - 10:44 AM

Won't be much help.  Push-processing increases density for information that was underexposed (it doesn't really make a film faster.)  Flashing adds some slight density to the shadows but since it also increases the base fog level, if your negative is underexposed and you want to brighten it in post, having foggier blacks isn't necessarily going to help much.  However, it was popular in the 1970's to combine a flash with push-processing in order to compensate for some increase in contrast for pushing.  I'd say that flashing maybe adds 1/6-stop of more shadow detail, which is hardly going to help you if you need another stop of speed.  Keep in mind that combining a flash with a 1-stop underexposure is going to make the flash look twice as heavy since you've altered the balance between the flash level and the image exposure level.


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