Depth of field

[Jim Feldspar]

Some cinematographers prefer to keep a specific f-stop throughout the film , or sequences , making sure that the contrast, definition ... among the scenes is kept controlled.

Others state that the mood of the scenes dictate the f-stop , those are concerned much more with the depth of field so under a sequence there will be scenes shot under different f-tops.

Since we have several ways to keep the contrast under control, i think the second approach contributes much more to tell the story , I would like to know yours opinion

tks

Roberto Laguna

 

"Some cinematographers prefer to keep a specific f-stop throughout the film , or sequences ,

making sure that the contrast, definition ... among the scenes is kept controlled."

 

How does changing lens aperture affect contrast?

[David Mullen ASC]

How does changing lens aperture affect contrast?

 

This is a somewhat debatable issue, something I tend to feel is a bit of a wive's tale, sort of "common wisdom" passed along that doesn't get challenged.

 

If you compare a shot made at f/2.8 versus f/16, assuming the exposure is correct in both cases (let's say an ND filter is used outdoors to enable you to shoot at f/2.8), the f/16 shot will feel more contrasty. But if you look at the ratio of key to fill on the subject, it hasn't really changed, unless this particular lens gets a little washed-out at a wide-open aperture.

 

But the difference in contrast is in the background. An out-of-focus background looks lower in contrast, because the highlights and shadows have blurred and blended over each other, putting more of the tonal range in the middle (the blacks and whites may still be there though). You can see this on a waveform monitor if you throw an image out-of-focus: most of the tones fall into the middle.

[Jim Feldspar]

This is a somewhat debatable issue, something I tend to feel is a bit of a wive's tale, sort of "common wisdom" passed along that doesn't get challenged.

 

If you compare a shot made at f/2.8 versus f/16, assuming the exposure is correct in both cases (let's say an ND filter is used outdoors to enable you to shoot at f/2.8), the f/16 shot will feel more contrasty. But if you look at the ratio of key to fill on the subject, it hasn't really changed, unless this particular lens gets a little washed-out at a wide-open aperture.

 

But the difference in contrast is in the background. An out-of-focus background looks lower in contrast, because the highlights and shadows have blurred and blended over each other, putting more of the tonal range in the middle (the blacks and whites may still be there though). You can see this on a waveform monitor if you throw an image out-of-focus: most of the tones fall into the middle.

That makes sense to me that it might look more as if the contrast would change than

there being an actual change. Thanks.

[Hasan khan]

It's rare, for example, for a director making a 35mm feature to ask for a "Citizen Kane" style deep-focus look. Most of them just expect the same depth of field characteristics of the typical 35mm feature made these days.

 

Im a newbie would you elaborate on the Citizen KAne comment.

[Frank Barrera]

Im a newbie would you elaborate on the Citizen KAne comment.

Citizen Kane is a film that should be studied for many reasons. One of which was the extreme use of deep focus where EVERTHING in the frame is kept in focus. This was accomplished using several techniques one of which was by using newly developed lenses and film stock that allowed for greater depth of field than had ever been possible before. Orson Welles felt this approach was necessary for the proper telling of his story.

 

We have become so accustomed to shallow depth of field that it is simply stunning to watch this movie again.

[Hasan khan]

Citizen Kane is a film that should be studied for many reasons. One of which was the extreme use of deep focus where EVERTHING in the frame is kept in focus. This was accomplished using several techniques one of which was by using newly developed lenses and film stock that allowed for greater depth of field than had ever been possible before. Orson Welles felt this approach was necessary for the proper telling of his story.

 

We have become so accustomed to shallow depth of field that it is simply stunning to watch this movie again.

I knew about the use of deep focus in CZ I just misinterpreted his post. Thank for clearing that up anyway.

 

I think I agree though, but saying that the envirnments and sets you shoot around are horrible is not really a good excuse and using deef focus and minimum editing (like Stanley Kubrick, Orson Welles in CZ, and Scorsese) would look bland to most viewers who want pure entertainment.

 

Its a different case entirely with commercials though and thats understandable. Im also disappointed to see even big-budget movies like Spider-man 2 look so boring; other than the SFX there is nothing in the movie that makes it look like a 250 million movie.

Edited January 14, 2007 by hasan

[David Mullen ASC]

In 35mm, creating a true deep focus effect takes a lot of work when indoors, and once you do that work, you better hope that the director knows how to take advantage of it and not just want to shoot close-ups against a bookshelf or something, but really stages in depth.

 

In defence of "Spider-Man" part of the story always involves the contradiction of Peter Parker's mundane existence and realistic problems (work, school, dating, etc.) with these big super-hero problems that he has to face, so there is a tendency for the movies to look straight-forward by design, to put Spider-Man in the real world.

[Hasan khan]

In 35mm, creating a true deep focus effect takes a lot of work when indoors, and once you do that work, you better hope that the director knows how to take advantage of it and not just want to shoot close-ups against a bookshelf or something, but really stages in depth.

 

In defence of "Spider-Man" part of the story always involves the contradiction of Peter Parker's mundane existence and realistic problems (work, school, dating, etc.) with these big super-hero problems that he has to face, so there is a tendency for the movies to look straight-forward by design, to put Spider-Man in the real world.

How is deep focus done? I think in CZ they had to reshoot the same scene several times and put them together in PP (the scene with the poison I think).

[David Mullen ASC]

When possible, the deep focus shots in "Citizen Kane" were done by using a wide-angle lens (a 25mm in this case) stopped down to f/16.

 

More extreme shots (extreme foreground elements) required efx work, either in-camera double-exposure or optical printing. The spoon in the f.g. is a good example because you'll notice that the bed in the midground is not in focus, but the farther door is in focus.

 

People have also used split-diopter filters and tilt-focus lenses for fake deep focus effects, but these weren't really available for motion picture work in "Citizen Kane" was made, although there were experiments around this time with a slanted lens, by Hal Mohr I think. The oldest movie I ever saw that used a split-diopter filter was the 1950's "King of Kings" but I'm sure there must be earlier examples.

[Hal Smith]

In 35mm, creating a true deep focus effect takes a lot of work when indoors, and once you do that work, you better hope that the director knows how to take advantage of it and not just want to shoot close-ups against a bookshelf or something, but really stages in depth.

Am I correct in assuming that sideways camera moves help to differentiate the various depths in the frame?

[Chris Cooke]

Ok, I just saw We Are Marshall and couldn't stop from commenting on the shallow focus of that movie. In some scenes, the shallow focus really added to the story and seemed to seperate the football players from what was going on around them but there seemed to be a lot of soft shots in the film. I did like the look and I thought that Shaun Hurlbut, ASC did a great job with lighting but it seemed to me that maybe when they were cutting the film, the director and editor chose good performances no matter how soft the shot was. This would be my main concern on a film like We Are Marshall with so many action shots coupled with a shallow DOF, you would have to talk with the director before hand to make sure that he didn't cut in any soft shots. Either that or get a flawless 1st AC.