Why overexpose?

C

calito

Active member
Hello wise people.
I've been reading some articles in the American cinematographer magazine where DPs often say that they overexposed a certain number of stops for certain shots.
Can anyone explain why this is a good practice,
and why so many DPs do this, and what would happen if they didn't?

Thanks guys
 
Depends on film stock, and the look that they are after. Personnaly shooting digital, I always try to avoid over exposing. Film is a different story.
 
In the directors commentary from Serenity Dvd Whedon talks about "blowing out" some shots on purpose. There is a time and a place for it.
 
agreed. It can be used in really impressive ways. But personally, I try to stay away from overexposure in video too. (unless of course I WANT something blown out, Duh!) :)
 
Braskar said:
Hello wise people.
I've been reading some articles in the American cinematographer magazine where DPs often say that they overexposed a certain number of stops for certain shots.
Can anyone explain why this is a good practice,
and why so many DPs do this, and what would happen if they didn't?

Thanks guys
Click to expand...

The reasons for overexposing are both technical and practical. When you overexpose your image in the photochemical process, the end result is a very dense negative, which holds more picture information, and holds up better over time. The general rule of thumb is "Overexpose by one, then print down by one." It can make your blacks blacker and also enhances color saturation.

If you underexpose, you get a weak negative and loss of detail. When you overexpose, you can always pull your "blown out" image down to a more manageable level.
 
dougspice said:
Well said. Don't try to apply film techniques to digital or vice-versa. Or rather, go ahead and try it, but know that it's probably not going to give you "good" results. Here's a bit more information and some useful technique:

http://www.kenrockwell.com/tech/fixing-dynamic-range.htm

(written for still cameras, but all the same ideas apply)
Click to expand...

Personally, I like to walk on the wild side when I shoot with the DVX. I've found that bumping up the master pedestal to somewhere between +7 and +10, and shooting on the nose or even half a stop above allows me a lot of leeway to play with the image when I go into post.
 
Over and under exposure can also lead to interesting effects on the grain structure of the footage. 21 Grams looks the way it does due to a combination of under exposing and pushing the negative in post. Certain stocks really come alive when they are pushed and pulled, over and under exposed.

Errr... Quite right.
 
But remember, you're talking about negative film there. The DVX (and all video cameras) perform more like reversal film. With reversal film, slight underexposure can really bring out saturation in the colors, and the same is true of video.

Negative film techniques don't apply, but reversal film techniques may.
 
dougspice said:
Huh. Got any samples of that to watch?
Click to expand...

Yeah, click here for a link to my demo reel.

The first piece, "Farewell," the third piece, "Cold Fear," and the fourth piece, "Movie Monster Insurance," were all shot with that technique I described.

The second piece, "The Couch" is the only piece I shot at exposure, with the master pedestal tuned down to around -3 or -5.
 
Iain said:
Yeah, click here for a link to my demo reel.

The first piece, "Farewell," the third piece, "Cold Fear," and the fourth piece, "Movie Monster Insurance," were all shot with that technique I described.

The second piece, "The Couch" is the only piece I shot at exposure, with the master pedestal tuned down to around -3 or -5.
Click to expand...

I love the look of Farewell. the windows are awesome. Reminds me of all of Spielberg's newer films. Cold Fear was just great! I got a couple good laughs out of it. and the last sequence looked really good as well.
 
Braskar said:
Hello wise people.
I've been reading some articles in the American cinematographer magazine where DPs often say that they overexposed a certain number of stops for certain shots.
Can anyone explain why this is a good practice,
and why so many DPs do this, and what would happen if they didn't?

Thanks guys
Click to expand...
Some DPs like to overexpose the back light to make the subject stand out more. It adds depth to the scene.
 
Iain, what gamma setting do you use with that technique? Fascinating idea. I'll have to try it out.
 
Film Crazy said:
Some DPs like to overexpose the back light to make the subject stand out more. It adds depth to the scene.
Click to expand...

EDIT: Just noticed that some of what I typed had already been said.

Actually, most DPs rate their film stock a half slower to reduce grain. With film, and especially with the newer Kodak Vision stocks, you have virtually unlimited data in the highlights, but underexposure gives you some grain issues. So overexposing is the natural way to go.

The final print is usually much more contrasty than the negative anyhow, so some highlight and shadow detail is lost. Contrary to popular belief, high dynamic range usually translates into a muddy, washed-out image. Contrasty images are much easier to "parse" and make sense of spacially, which facilitates fast cutting and makes movies much easier and more intuitive to watch. Of course, harsh washed out highlights look ugly so having the smooth roll-off in the highlights is nice and gives you a contrasty but not harsh image.

For video, over-exposure is pretty much only used as an effect. I don't get the thing about backlights. If you want a stronger one, just move it closer to the subject or use a stronger light. The over-exposure would wash out the image anyhow, making the contrast less noticeable, instead of more. Also, I don't know how you'd go about "over-exposing" one light but not others.

In general, over-expose film, under-expose video (although since video is WYSIWYG, you should really try to expose correctly every time.)
 
Shaw said:
Iain, what gamma setting do you use with that technique? Fascinating idea. I'll have to try it out.
Click to expand...

Thanks for the compliments, guys!

I don't remember what my gamma setting was. I sold my DVX last month to facilitate HVX200 funding :)

I think I used a HIGH setting to get as much info as I could out of the image. I never messed with the GAIN settings, BTW. I was already pushing the limits with my noise levels as is.
 
Policar said:
EDIT: Just noticed that some of what I typed had already been said.

Actually, most DPs rate their film stock a half slower to reduce grain. With film, and especially with the newer Kodak Vision stocks, you have virtually unlimited data in the highlights, but underexposure gives you some grain issues. So overexposing is the natural way to go.

The final print is usually much more contrasty than the negative anyhow, so some highlight and shadow detail is lost. Contrary to popular belief, high dynamic range usually translates into a muddy, washed-out image. Contrasty images are much easier to "parse" and make sense of spacially, which facilitates fast cutting and makes movies much easier and more intuitive to watch. Of course, harsh washed out highlights look ugly so having the smooth roll-off in the highlights is nice and gives you a contrasty but not harsh image.

For video, over-exposure is pretty much only used as an effect. I don't get the thing about backlights. If you want a stronger one, just move it closer to the subject or use a stronger light. The over-exposure would wash out the image anyhow, making the contrast less noticeable, instead of more. Also, I don't know how you'd go about "over-exposing" one light but not others.

In general, over-expose film, under-expose video (although since video is WYSIWYG, you should really try to expose correctly every time.)
Click to expand...

I agree Policar (always enjoy your posts; always so well thought out, insightful and something to offer)

I have always shot as the DVX Manual originally suggested (- 3 ) and it always works for my needs.

Overesposing video is a bad idea. Once it's gone, it's gone.
 
Of course it is.

But is it not prudent to have the option in post to have as much visual information as possible and then blow it out till hearts content ?

Maybe best to start under or over by a few stops but save the blow out's for post ?
 
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