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Over exposing highlights, transferring down


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#1 Bruce James

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Posted 06 November 2007 - 01:37 PM

Hi.

I'm shooting a sci-fi short this weekend on super 16mm (no time for a test) and I'm wondering if anyone can give me some tips on a look I'm going for in the exteriors.

The story takes place in the near future after a global catastrophe that has made the climate colder and the sun more dangerous because of a thinned atmosphere. So I'm looking for a lot of blown-out highlights both to "show" the danger of the sun and hide some background details.

I forget what this is called, but what I was thinking I would do is overexpose the highlights and then in the video transfer, "print" down so that middle gray is middle gray, but there are only a couple of stops between there and totally blown-out white.

I'm shooting Vision2 200T. I was thinking of over-exposing two stops. Am I on the right track here?

Any suggestions?

Thanks,

- Bruce
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#2 Saul Rodgar

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Posted 06 November 2007 - 04:24 PM

I'm shooting Vision2 200T. I was thinking of over-exposing two stops. Am I on the right track here?


Yikes! two stops over in daylight is quite radical. Even using Kodak **17, with its incredible latitiude, I think you are taking a huge risk. This assuming that you would filter your lens to compensate daylight on tungsten film, right? 125 ASA after 85b filtering is still blazing fast (and hot) at 24 fps. Especially since you haven't done any testing, but maybe you'd like the look of nothing but white on film. With 200T you would want to bring the ASA down to 40 from 125 after your tungsten to daylight compensation, unless you are shooting in dusk. Otherwise you probably would see nothing but white and some vague shapes.

What I would do is: shoot your grayscale 2 stops over and the rest of the footage exposed normally, even underexposed 2/3 of a stop. I would also shoot with a polarizer -ND would help a lot- and plenty of backlight, so your mids and lows are nice and contrasty to your over-the-top highlights, exposing for the mids. My guess is trying not to keep the highlights blasting on someone head on, unless that's what you are going for: the post-armagedon your-skin-and-everything- else-is-frying look.

If you shoot that way you can ask the telecine/ DI operator to compensate in post for the grayscale only (set-and-forget) and the rest of your footage will be two stops over mostly on the highlights: but only because it was telecined/DI'd that way. Your actual camera original footage will have the right density, for future tweaking. If you do that your footage won't be ruined should you feel 2 stops were too much, which is likely.

That's what I would do anyway.

Good luck keep us posted . . .
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#3 Saul Rodgar

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Posted 06 November 2007 - 04:34 PM

What I mean: is print up from properly exposed footage instead of printing down from blown out footage. The detail that you lose in your camera original is gone forever, so printing up form proper density negative is a lot safer. The last thing you want is to realize later your investment and hard work is ruined.
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#4 Chris Walters

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Posted 06 November 2007 - 04:41 PM

Hi.

I'm shooting a sci-fi short this weekend on super 16mm (no time for a test) and I'm wondering if anyone can give me some tips on a look I'm going for in the exteriors.

The story takes place in the near future after a global catastrophe that has made the climate colder and the sun more dangerous because of a thinned atmosphere. So I'm looking for a lot of blown-out highlights both to "show" the danger of the sun and hide some background details.

I forget what this is called, but what I was thinking I would do is overexpose the highlights and then in the video transfer, "print" down so that middle gray is middle gray, but there are only a couple of stops between there and totally blown-out white.

I'm shooting Vision2 200T. I was thinking of over-exposing two stops. Am I on the right track here?

Any suggestions?

Thanks,

- Bruce


If you want the highlights to be blown out on the finished film then you just overexpose those places compared to your middle gray in the scene. If you over expose them and then print down you are just bring the whole light level down, essentially bringing the highlights back to normal, but crushing/darkening the grays and blacks. So it depends on the result you want. I print down to lessen the visible grain and boost the saturation slightly. For instance I overexposed my entire movie by 2/3 of a stop and then brought it back down in post to crush the blacks and reduce the grain because I was shooting 500T.. Hope that helps you understand it a little.. Btw overexposing 200T by 2 stops is like shooting at 50T. Thats a lot of light!! A T4 is 800 footcandles.... Good luck with the project and have fun!!

Chris
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#5 Chris Walters

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Posted 06 November 2007 - 04:45 PM

What I mean: is print up from properly exposed footage instead of printing down from blown out footage. The detail that you lose in your camera original is gone forever, so printing up form proper density negative is a lot safer. The last thing you want is to realize later your investment and hard work is ruined.

Its actually safer to overexpose slightly than underexpose a lot. There is more latitude on negative at least on the shoulder part of the curve than the toe. Meaning you have more room for error on the overexposure side and printing down than underexposure going up. By printing up you are also increasing the apparent grain structure... which unless you like that look is not usually a good thing and I say usually for a reason.

Chris
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#6 Bruce James

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Posted 06 November 2007 - 04:55 PM

Yikes! two stops over in daylight is quite radical. Even using Kodak **17, with its incredible latitiude, I think you are taking a huge risk. This assuming that you would filter your lens to compensate daylight on tungsten film, right? 125 ASA after 85b filtering is still blazing fast (and hot) at 24 fps. Especially since you haven't done any testing, but maybe you'd like the look of nothing but white on film. With 200T you would want to bring the ASA down to 40 from 125 after your tungsten to daylight compensation, unless you are shooting in dusk. Otherwise you probably would see nothing but white and some vague shapes.



What I would do is: shoot your grayscale 2 stops over and the rest of the footage exposed normally, even underexposed 2/3 of a stop. I would also shoot with a polarizer -ND would help a lot- and plenty of backlight, so your mids and lows are nice and contrasty to your over-the-top highlights, exposing for the mids. My guess is trying not to keep the highlights blasting on someone head on, unless that's what you are going for: the post-armagedon your-skin-and-everything- else-is-frying look.

If you shoot that way you can ask the telecine/ DI operator to compensate in post for the grayscale only (set-and-forget) and the rest of your footage will be two stops over mostly on the highlights: but only because it was telecined/DI'd that way. Your actual camera original footage will have the right density, for future tweaking. If you do that your footage won't be ruined should you feel 2 stops were too much, which is likely.

That's what I would do anyway.

Good luck keep us posted . . .


I only have one exterior location and two shots to get there and I have about two hours at the end of the day when it's in a building shadow, so I'm not too concerned about getting in the right range with an 85B and some ND.

As far as nothing but white on film, what I'm looking for is a compressed exposure range where it's maybe two stops to white from middle gray, so a decent amount of white is part of the objective.

Wouldn't I want to shoot the grayscale at 2 stops under if I were going this route? I would think that transferring as if the two stops over exposed grayscale were middle gray would increase my exposure range above middle gray.

The reason I wouldn't expose normally would be so I would be getting film white instead of video white. But maybe that's not worth worrying about.

I'm not sure that I communicated what I'm going for effectively. I want to end up with an unnatural-looking exposure range above middle gray. So white is only a couple of stops above middle gray. I wish I could think of a movie I've seen this in to better explain. Maybe it will come to me.

Thanks for the response.
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#7 Chris Walters

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Posted 06 November 2007 - 05:03 PM

Yikes! two stops over in daylight is quite radical. Even using Kodak **17, with its incredible latitiude, I think you are taking a huge risk. This assuming that you would filter your lens to compensate daylight on tungsten film, right? 125 ASA after 85b filtering is still blazing fast (and hot) at 24 fps. Especially since you haven't done any testing, but maybe you'd like the look of nothing but white on film. With 200T you would want to bring the ASA down to 40 from 125 after your tungsten to daylight compensation, unless you are shooting in dusk. Otherwise you probably would see nothing but white and some vague shapes.

What I would do is: shoot your grayscale 2 stops over and the rest of the footage exposed normally, even underexposed 2/3 of a stop. I would also shoot with a polarizer -ND would help a lot- and plenty of backlight, so your mids and lows are nice and contrasty to your over-the-top highlights, exposing for the mids. My guess is trying not to keep the highlights blasting on someone head on, unless that's what you are going for: the post-armagedon your-skin-and-everything- else-is-frying look.

If you shoot that way you can ask the telecine/ DI operator to compensate in post for the grayscale only (set-and-forget) and the rest of your footage will be two stops over mostly on the highlights: but only because it was telecined/DI'd that way. Your actual camera original footage will have the right density, for future tweaking. If you do that your footage won't be ruined should you feel 2 stops were too much, which is likely.

That's what I would do anyway.

Good luck keep us posted . . .


I think you might have things reversed here. The lower the ASA the slower it is and requires more light. If he overexposes his grey scale 2 stops the operator is going to bring the whole scene down 2 stops and if he exposes it normally than his entire scene would be underexposed by 2 stops. Not sure what good that will do...

Chris
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#8 Saul Rodgar

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Posted 06 November 2007 - 05:09 PM

Wouldn't I want to shoot the grayscale at 2 stops under if I were going this route? I would think that transferring as if the two stops over exposed grayscale were middle gray would increase my exposure range above middle gray.


Yes, under! Sorry for the dislexic slip up!
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#9 Chris Walters

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Posted 06 November 2007 - 05:11 PM

I only have one exterior location and two shots to get there and I have about two hours at the end of the day when it's in a building shadow, so I'm not too concerned about getting in the right range with an 85B and some ND.

As far as nothing but white on film, what I'm looking for is a compressed exposure range where it's maybe two stops to white from middle gray, so a decent amount of white is part of the objective.

Wouldn't I want to shoot the grayscale at 2 stops under if I were going this route? I would think that transferring as if the two stops over exposed grayscale were middle gray would increase my exposure range above middle gray.

The reason I wouldn't expose normally would be so I would be getting film white instead of video white. But maybe that's not worth worrying about.

I'm not sure that I communicated what I'm going for effectively. I want to end up with an unnatural-looking exposure range above middle gray. So white is only a couple of stops above middle gray. I wish I could think of a movie I've seen this in to better explain. Maybe it will come to me.

Thanks for the response.

I'm not sure you can physically compress the latitude of the film, but you can always give the illusion of this by limiting the amount of grey tones you have in front of the lens. Meaning light the areas of your scene with a middle grey, dark and white instead of a dark gray light gray. Good luck though
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#10 Michael Nash

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Posted 06 November 2007 - 05:23 PM

I was thinking of over-exposing two stops. Am I on the right track here?

Any suggestions?


I think you're on the right track, but unfortunately you really do need to test to see that the results look the way you want them to. The highlight response of film is a gently sloping curve, not a straight line, so it's impossible to put a precise number on how much overexposure will result in all loss of detail, without testing.

To "overexpose and print down" you would simply rate your film stock two stops slower (50 ASA in this case) and shoot your gray scale -- and everything else -- normally (at 50 ASA). The telecine colorist would bring down the brightness of the entire image so that the gray card and midtones look "normal."

There are a couple problems with this though. One, very high densities on a negative create noise in the telecine transfer, which may or may not help the look you're going for. Two, since the highlight response of film kind of "flattens out," you might end up with a washed-out looking low-contrast midtones in addition to burned-out highlights. Again, only testing will confirm the actual results.

But ALL of this stuff is malleable in telecine and post. You might be better off exposing your film closer to normal and just cranking up the contrast and highlight level in the transfer or in post.

Other sci-fi projects have done this kind of effect by performing a bleach-bypass on the negative, but that too requires testing to get the desired results.
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#11 Bruce James

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Posted 06 November 2007 - 06:22 PM

I think you're on the right track, but unfortunately you really do need to test to see that the results look the way you want them to. The highlight response of film is a gently sloping curve, not a straight line, so it's impossible to put a precise number on how much overexposure will result in all loss of detail, without testing.

To "overexpose and print down" you would simply rate your film stock two stops slower (50 ASA in this case) and shoot your gray scale -- and everything else -- normally (at 50 ASA). The telecine colorist would bring down the brightness of the entire image so that the gray card and midtones look "normal."

There are a couple problems with this though. One, very high densities on a negative create noise in the telecine transfer, which may or may not help the look you're going for. Two, since the highlight response of film kind of "flattens out," you might end up with a washed-out looking low-contrast midtones in addition to burned-out highlights. Again, only testing will confirm the actual results.

But ALL of this stuff is malleable in telecine and post. You might be better off exposing your film closer to normal and just cranking up the contrast and highlight level in the transfer or in post.

Other sci-fi projects have done this kind of effect by performing a bleach-bypass on the negative, but that too requires testing to get the desired results.


Thanks for the reply. This makes sense. I think I probably will just shoot it normal and see what I can do in the transfer and in post. I'll definitely shoot one or two takes overexposed, though, to see what I come up with for future use.

Thanks again.
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#12 Michael Nash

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Posted 06 November 2007 - 06:38 PM

I'll definitely shoot one or two takes overexposed, though, to see what I come up with for future use.


That's always the best way! On a student/indy budget there's rarely the $$ for proper tests, so you try to experiement whenever and however you can (without causing detriment the to project of course). I've learned as much from my "mistakes" as I have from proper testing.
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