SHUTTERLESS!

[Mitch Perkins]

You can get similar results without undesiderable effects "flashing" the film before or after shooting.

Carlos

The shutterless camera exposes film continuously to light reflected from a particular scene.
How many stops does one gain with a 360 deg. shutter, as opposed to a 180 deg. shutter?
How many stops does one gain simply flashing the film to an arbitrary light source, (not a scene), of say 3200 K for 1/24th of a second before/after shooting?

Mitch

[Carlos 8mm]

The shutterless camera exposes film continuously to light reflected from a particular scene.
How many stops does one gain with a 360 deg. shutter, as opposed to a 180 deg. shutter?

Of course, +1 f-stop of gain.

How many stops does one gain simply flashing the film to an arbitrary light source, (not a scene), of say 3200 K for 1/24th of a second before/after shooting?

Preflashing the film allows to obtain 1/2 -3/4 f stop of gain. Post flashing allows close to 1 f-stops of gain, with a certain loss of contrast, of course.

The differences beetwen Shutterless and pre/post flashing film shooting is the fact that you can shoot with the original shutter speed of the camera to get detailed and more "frozen" images.


I´ve got some examples of pre-flashed 16 mm footage done in the 1950´s. Gonna try to post today.

Carlos.

[christoph]

You can get similar results without undesiderable effects "flashing" the film before or after shooting.

no you can't... flashing lowers contrast and adds some shadow detail in the whole picture while an removed shutter will expose the film during transport, resulting in streaks... no flashing in the shadow area if there are no lights above or below the shadow area. actually we shouldn't be using the word "flashing" at all in this context.

How many stops does one gain with a 360 deg. shutter, as opposed to a 180 deg. shutter?

to be technically correct, none.
if you had a camera where the film transport could happen in a 1/1000sec or so, you'd gain nearly one full stop (but film cameras need at least 1/100sec for the transport, so if you're lucky you get 1/2 stop extra).. this is what happens with video cameras if you set the shutter to 1/25sec (or 1/30 in ntsc land) since they dont have to close the shutter for transport. most video cameras throw away half of the vertical resolution if you do that though.

How many stops does one gain simply flashing the film to an arbitrary light source, (not a scene), of say 3200 K for 1/24th of a second before/after shooting?

the concept of flashing is not that simple - you can't just flash for "1/24th sec". how bright is the light, at what distance, what sensitivity is the film?
a common way to indicate the strenght of flashing is to read a graycard and underexpose X stops. with reversal film, flashing at 3 stops under might be a good start, but it depends on a lot of factors, so tests are absolutely necessary.
again, you do not really "gain" f-stops since you change the characteristic of a stock, and more often than not the results are not pretty (you need some black in the picture somewhere). it's cool if you like to experiment, but if it was such a great idea everybody would be doing it, no? ;)

++ christoph ++

[christoph]

[Preflashing the film allows to obtain 1/2 -3/4 f stop of gain. Post flashing allows close to 1 f-stops of gain, with a certain loss of contrast, of course.

i'd be curious where you got this info from, since i always thought that preflashing and postplashing result in nearly the same effect.

++ christoph ++

[Mitch Perkins]

The shutterless camera exposes film continuously to light reflected from a particular scene.
How many stops does one gain with a 360 deg. shutter, as opposed to a 180 deg. shutter?

Of course, +1 f-stop of gain.

How many stops does one gain simply flashing the film to an arbitrary light source, (not a scene), of say 3200 K for 1/24th of a second before/after shooting?

Preflashing the film allows to obtain 1/2 -3/4 f stop of gain. Post flashing allows close to 1 f-stops of gain, with a certain loss of contrast, of course.

The differences beetwen Shutterless and pre/post flashing film shooting is the fact that you can shoot with the original shutter speed of the camera to get detailed and more "frozen" images.


I´ve got some examples of pre-flashed 16 mm footage done in the 1950´s. Gonna try to post today.

Carlos.

Another difference is that with the shutterless camera, you need not post/pre flash the film!
Please note my exact words,"in effect", WRT flashing. The main gain here is the incredibly groovy dancing light streaks. By braking the drive gear, the streaks can be made to "cycle". It looks neat, believe me, or I would not have spent the time composing the post.

Cheers,
Mitch

[mattias]

i always thought that preflashing and postplashing result in nearly the same effect.

i don't know how big the difference is, but the reason there is one is that pre flashing "sensitises" all the crystals, while post flashing obviously only affects those that are not exposed already.

/matt

[nasq]

Yes, this vertical streaking doesn't have anything to do with flashing film. It's a neat effect used on many films, for example in Saving Private Ryan. As far as I remember, they threw the shutter out of sync to create some random streaking.

[mattias]

Yes, this vertical streaking doesn't have anything to do with flashing film.

i don't think anybody has suggested it did either?!?

/matt

[Mitch Perkins]

it's cool if you like to experiment, but if it was such a great idea everybody would be doing it, no? ;)

++ christoph ++

I use it to shoot weddings on Tri-X for a local production company. In low-light situations where I would otherwise be unable to capture any usable image at all, the shutterless comes through. The bride's white dress, *in effect* flashes her face, removing darkness from around the eyes - very important in this case. There are still blacks in the image.
One time these little kids were blowing soap bubbles, they were backlit, floating all over the place. I couldn't believe my eyes on viewing the processed film.

As for who's doing it -

http://www.panavision.co.nz/main/rentals.asp?cat=PANMOS

"variable shutter 11.2 to 180 degrees"

See also "The Limey" during Terence Stamp's flashbacks of his daughter. There is a gorgeous commercial running here in Canada wherein a woman suffering a migraine attempts to "turn "off" the variably streaking city-view outside her window.

A note on retaining blacks with Tri-X;
In order to obtain a "wedding-cake-white" look, with no facial imperfections visible on either bride or groom, I have exposed Tri-X outdoors on a sunny day at f5.6 and even f4 (180 deg. shutter in place). Once again, trees in the background are nicely black.

Final note: these streaks are actually kinda hard to generate even sans shutter - stopping down will cause them to quickly fade.

Mitch

[mattias]

hmm, how about replacing the opaque shutter disc with a ground glass?

/matt

[christoph]

i don't know how big the difference is, but the reason there is one is that pre flashing "sensitises" all the crystals, while post flashing obviously only affects those that are not exposed already.

well, my understanding is that the point is that a siver halide needs a certain amount of light photons to be "activated" (ie. that the developer can reduce it to metalic silver).
as en example, lets say we have five silver halides, one that gets hit by 0 photon (A), one by 1 (B), one by 2 (C), one by 3 (D), one by 4 (E). now lets say it needs 4 photons to start the reduction process. obviously, only halide E will form any image.
enter flashing procedure:
we post flash the whole film uniformly so that every halide gets hit by 2 photons.. now suddenly the halide C and D get black too, revealing shadow detail. imagine we do the same thing with preflashing, the amount of photons per halide is exactly the same, the only difference is that film sensitivity gets worse on multi exposures, so on the second (real, non-flash) exposure the haides are already slightly tired. i know this becomes an issue if you do 8 times multi exposures where you have to calculate for the light loss, but i didn't think it makes a big difference in low light flashing, this is why i was wondering where the info comes from.

in the example above, the best max amount of flashing would be 3 photons per halide, more than that and you just raise base fog.

++ christoph ++

[mattias]

good analysis. it's not quite that simple though, since the chrystals group together in what we call grain, and they are different in size thus require different amounts of energy to change form, plus what happens to one crystal in such a group affects the others. this is why different film stocks perform differently. if it was just optics and chemistry on the ion level all stocks would perform exactly the same.

/matt

[christoph]

good analysis. it's not quite that simple though, [...]

i know, but i thought that it's the best i can do in reasonable time with my crude english ;)

if somebody is really interested he should read up some advanced literature.. i strongly recommend the books of Jost Marchesi for those that understand german.. like:
http://www.amazon.de/exec/obidos/ASIN/3 ... 83-8903245 (might even be translated to english)

++ christoph ++

[Carlos 8mm]

Hi, ya

Here are two examples of pre-flashing film in a mid 1950´s 16 mm maked by an old amateurish filmmaker of my city:






That man told me that he always used Ferrania ISO 40 B&W reversal stock.
A High contrast, sharper and very fine grain film. To shoot indoors He preferred to pre-flash the film to increase the film speed. There is a loss in contrast and sharpness, of course. He learned this method in a book for amateurish Filmmakers . I found a similar book where different methods are explained to increase the film speed, (pre/post flashing) and chemical procedures, really very interesting.

This is a frame of a film shoted with Ferrania ISO 40 B&W reversal stock in nomal situations:

[/img]

[Mitch Perkins]

hmm, how about replacing the opaque shutter disc with a ground glass?

/matt

Hi Matt,

The shutter in the Nikon is press-fitted to the collar, which mounts in a strange off-center way to the drive shaft. But Nizos use a shutter that is screw-mounted to a cog which runs the pull-down claw. Nizo shutters are harder to access though not impossible (heh heh).

Point is, we did cut out and mount an orange, semi-opaque shutter in an old nizo, but instead of putting it back together, we ended up shooting the interior of the Nizo with this weird shutter spinning around!

Love them Nizos for accessibility - the lenses come off pretty easy, and can be replaced with almost whatever you like, as long as you re-calibrate the "interior lens". My S800 didn't have macro, so I mounted a lens from a dead 6080, and it works great.

If anyone wants, we could start a new thread on the topic of mounting different lenses on Nizos.

All the best,
Mitch